Topic outline

  • TOPIC AREA 1: SOIL SCIENCE

    Unit 1: Introduction to Agriculture

    Introduction

    The foods we eat every day are all deliberately produced at a given place. Examples include vegetables, meat, cereals, fruits and milk, among others. Some of them are produced in our country. Some are imported from other countries. You shall understand why foods are produced and why it is important to study Agriculture as a subject in this unit.

    Key unit competency

    After studying this unit, I should be able to:

    a) Define the term Agriculture.

    b) Explain correctly the importance of Agriculture.

    c) Explain the branches of Agriculture and their relevance to human life.

    d) Identify the different farming systems.

    Unit Outline

    1.1 Definition of Agriculture

    1.2 Socio-economic importance of Agriculture

    1.3 Branches of Agriculture

    1.4 Farming systems

    1.1 Definition of Agriculture

    Activity 1.1: Research Activity

    Using textbooks and the internet, find out the meaning of Agriculture. Interact with your classmates to know what they have found out. Prepare a report and present to the rest of your class.

    I have found out that…

    Agriculture is the Art and Science of cultivating land, growing crops and rearing livestock.

    The facts:

    Agriculture is regarded as an Art since it involves the application of human skills in processes such as milking, construction of farm structures, measuring land size and operating various farm machineries. As a Science, Agriculture requires application of various intellectual and practical skills. Examples are observation, experimentation and analysis. Below is a chart showing the various agricultural activities in categories of art and science.

    Self-evaluation Test 1.1

    1. Explain how Agriculture is being practised in your local environment.

    2. Do you think those Agricultural practices are important? Why?

    1.2 Socio-economic importance of Agriculture Generally, Rwanda’s economy relies heavily on Agriculture. About a third of Rwanda’s Gross Domestic Product (GDP) is accounted for by Agriculture. In Rwanda, the Agricultural sector meets about 90% of the national food needs and it generates more than 70% of the country’s export revenues. This subunit, seeks to appreciate the socio-economic importance of Agriculture to our households and country at large.

    Activity 1.2

    1. Go for a field trip to a nearby farm during the harvesting period. Ask as many questions as you can to the workers with the aim of understanding the various benefits of Agriculture. Note down the important points and prepare a report after the visit. 2. Try to think of other benefits that can come from practising Agriculture. 3. Do a class presentation to the rest of the class on your findings.

    I have discovered that…

    The socio-economic benefits of Agriculture can be presented in terms of:  

    • Food supply  

    • Source of employment  

    • Source of raw materials for industries 

     • Source of capital 

     • A recreational activity 

     • Foreign exchange earner  

    • Source of medicinal products

    The fact

    a) Food supply

    Agriculture provides food needed to give us energy to engage in productive activities. The food comes from crops such as cereals, vegetables and fruits, and from livestock products, such as eggs, meat and milk. Proper feeding promotes good health. A healthy nation leads to enhanced productivity in all sectors. This ensures that development takes place.

    Activity 1.3

    Visit a nearby agricultural market and list some of the most common agricultural produce being sold. Create a table and record the number of stalls in which certain foods are sold. Such foods can be vegetables, fruits or cereals (specify their names). From the results you will have obtained, come up with a bar graph.

    Discussion corner!

    From the graph in Activity 1.3 above, answer the following questions:

    a) Which food is the most common in the market?

    b) Which food is the least popular in the market?

    c) Find out possible reasons for the answers in (a) and (b) above.

    d) Give appropriate recommendations that can help to reduce the disparity.

    b) Source of employment

    As we have seen earlier, Agriculture accounts for a large part of Rwanda’s Gross Domestic Product (GDP). This means that many Rwandans, especially those living in rural areas, are engaging, either directly or indirectly, in the agricultural sector. Direct involvement in the agricultural sector is when one actually works on the farms. This can be as a farm manager or any kind of casual worker in the farm. Indirect involvement can be when one works in a crop processing company or any other industry that uses agricultural produce. Those working in industries that manufacture farm inputs and other agrochemicals are also under the indirect employment category. From these, we draw that indeed Agriculture is a crucial industry. We should therefore be keen on learning more about agriculture; not just to be employed, but to be the ones creating employment opportunities for others.

    Discussion corner!

    Think of other agricultural activities you can come up with to expand the scope of farming carried out in your locality. Note them down and present them in class.

    c) Source of raw materials for industries

    The various industries present in our country play a major role in developing our economy. In most industries, raw materials are usually processed into more useful commodities. Since Rwanda is an agricultural country, most industries in the country are agriculture-based. Examples of such industries are: • Leather tanning factory in Gikondo.

    • Inyange industries at Masaka that processes milk and fruits.

    • Food and fruit processing industry at Nyirangarama in Rulindo.

    • Tea factories such as Pfunda in Rubavu, Mulindi in Gicumbi and Rubaya in Nyabihu.


    • Breweries such as Bralirwa in Rubavu and Skol at Kigali.

    • Sugar factories such as Kabuye in Gasabo.

    • Rice processing units in Bugarama.
    As in any other industry, it is also important for the participants of the agricultural

    d) Source of capital


    There are two forms of farming; subsistence farming and farming for commercial purposes. Subsistence farming refers to the kind of farming whereby the farmer only focuses on producing food for his/her household. Farming for commercial purposes on the other hand is mainly for business. The farmer sells produce from his/ her farm in order to gain profits. From what they will have earned, the farmers will now be able to cater for their household needs and even have some extra cash to invest in other entrepreneurial ventures. The government also gets revenue through the taxes levied on farmers. Such income enables the government to finance its recurrent expenditure and the various national development projects; such as provision of education facilities, health facilities, road construction among others.

    e) Source of medicinal products

    Various agricultural products, from both animals and plants, have been used since time immemorial to treat various ailments and diseases. Despite the fact that today there is reduced use of herbs, some of these products are still being used as raw materials in the processing of the currently popular tablets and syrups.

    Health check! You should only take medicine that has been prescribed by a qualified doctor.

     f) Foreign exchange earner

    Activity 1.4: Research activity

    Find out the meaning of the term foreign exchange. You can use textbooks in the library or the internet. Note down the meaning and discuss with your friends in the classroom.

    I have discovered that…

    The money that the government earns from exporting produce to other countries is what we call foreign exchange.

    The facts

    Agriculture is a major source of foreign exchange for Rwanda. It accounts for about 70% of the country’s total export revenues. Some of the most valuable export crops in Rwanda include tea, coffee, fruits, vegetables, flowers (especially roses) and pyrethrum.

    g) A recreational activity

    Discussion corner!

    Read this story

    Uwase had a big compound in her home. She wondered what she was going to do to make her home more beautiful and welcoming. One day, she went to visit her friend Keza. Keza’s home had beautiful flower gardens at almost every corner of the compound. It looked amazing. Uwase was impressed. Study questions

    1. What would you advice Uwase to do in her big compound?

    2. What benefit is associated with Keza’s home?

    Apart from just providing food and all the other listed uses, agriculture can also be carried out solely for recreational reasons. An example would be when a farmer sets aside a small piece of land to plant flowers for beautification purposes. Flower gardens normally improve the general appearance of any given place. This can be done in private compounds, public places such as roads, schools, church compounds and hospitals. Also, fish ponds can be established to carry out fishing as a recreational activity.

    Activity 1.5

    With the help of your teacher, find places in your school compound that you can establish flower gardens. Look for appropriate plant seedlings and carefully plant them. You should be able to take care of those plant seedlings until when they are fully grown plants. 

    Self-evaluation Test 1.2

    Study the table given below about a coffee farmer called Habimana then answer the questions that follow. Habimana incurred the following expenses in his coffee farm in the year 2015.

    1.3 Branches of Agriculture

    Activity 1.6: Research activity

    Using reference books or the internet, find out the branches of Agriculture. Prepare a report and present it in class.

    I have discovered that…

    The branches of Agriculture are: 

    • Soil science

     • Crop husbandry 

    • Animal husbandry  

    • Agricultural economics

    • Agricultural engineering

     • Horticulture  


    The facts

    a) Soil science

    This is the study of soil as a natural resource that occurs on the surface of the earth. The specific aspects of soil studied include soil formation, classification and mapping, physical, chemical, biological and fertility properties of soil among others. These properties are studied in relation to the use and management of soils.

    b) Crop husbandry

    Crop husbandry refers to all agricultural activities done to crops from the time crops are planted to the harvesting time. It also includes agricultural produce processing and storage. All these practices aim at ensuring that a crop is provided with the best conditions for optimum growth in the field. This ensures optimum returns in terms of quantity and quality of produce.

    c) Animal husbandry

    This refers to management and care of farm animals for a profit. It can also be defined as the practice of selectively breeding and raising livestock to promote desirable traits in them for sale, sports, pleasure or research. In animal husbandry, genetic qualities and behaviors considered to be advantageous are further developed.

    d) Agricultural economics

    Discussion corner!

    Read this story

    Gatete grows plantains. His farm has grown bigger as compared to the one he had before. The produce is now becoming overwhelming. He needs better structures to help him get the best out of his farm. What should Gatete do?


    Agricultural economics is an applied field of economics. It is concerned with the application of economic theories in improving the production and distribution of food and other agriculture-related materials. Agricultural production involves the use of limited resources such as land, capital and labour. These resources are also known as factors of production. Each of these must be properly allocated in order to minimise costs while at the same time maximise on revenue. This will in turn result in high profits which is the sole objective of agricultural economics.

    Activity 1.7

    Visit to an agricultural farm

    Visit a nearby farm and find out practices that farmers carry out to ensure that the limited resources used in Agriculture are well-utilised. Note them down and present them in class.

    What I discovered...

    Some practices that help to ensure that Agricultural economics is achieved include:

    i. Application of principles of economics

    ii. Proper accounting iii. Proper record keeping

    iv. Good marketing strategies



    e) Agricultural engineering

    In this branch of Agriculture, engineering, science and technology are applied. Agricultural engineering mainly involves knowledge and usage of farm machines and equipment. It usually deals with the development of new systems and practices that aim at addressing problems of inefficiency facing the agricultural sector.

    f) Horticulture

    This is the branch of Agriculture that deals with the growing of highly perishable crops. Such crops require high level farm management skills, from planting time, to the time of harvest and also how the crop will be marketed.

    Activity 1.8

    1. Visit a horticultural farm and find out the types of crops grown there.

    2. Find out why the farmer chose to grow the crops. Are there any advantages of the crop over others?

    What I have discovered...

    Horticulture is divided into three main categories. These are:

    • Floriculture – Growing of flowers.

    • Olericulture – Growing of vegetables.

    • Pomoculture or pomology – Growing of fruits.

    Activity 1.9: Research Activity

    Find out about some of the problems that farmers face. Find out possible solutions and present them in class.

    The facts

    Some of the problems that face the agricultural sector and their solutions include:

    • Inadequate capital for farmers – Cooperative Societies have been established to help farmers obtain capital.

    • Unpredictable weather patterns – Farming methods that are independent of weather patterns have been established through use of irrigation systems and the green houses among others.


    • Crop pests and diseases – Pesticides and acaricides are used to deal with these respectively.

    • Animal parasites and diseases – Livestock can be sprayed using various chemicals to prevent them from succumbing to attacks by various external parasites and diseases. External parasites can be dealt with through use of dewormers and other drugs.

    • Inadequate knowledge and lack of proper farming skills – Farmers can be trained about the various farming techniques that will ensure that they have maximum output.

    • Inadequate awareness of proper farm inputs – Farmers can be encouraged to use certified seeds, effective farming machines and to keep records of all these to ensure accountability.

    Self-evaluation Test 1.3

    1. Among all the named branches of Agriculture, which ones do you think can be applied in your school farm and why?

    2. Why is floriculture popular in highlands?

    3. Why is studying soil important to farmers?

    4. Which three fields of study are combined with Agriculture in Agricultural Engineering?

    1.4 Farming systems

    Farming system refers to the way farm enterprises (resources) are organised and utilised. Different farm activities and enterprises are organised in various ways depending on the resources available to the farmer. These resources include land, capital, labour and human resource

    Activity 1.10
    Field trip

    1. Go for a field visit to a nearby farm and find out the various types of farming systems used.

    2. Compare and contrast the various farming systems you have learnt about from your trip.

    3. Come up with a report and do a presentation in the class.

    I have discovered that…

    Farming systems help farmers to organise and utilise their farm resources appropriately. The various types of farming systems are:

    • Monocropping 

    • Intercropping 
    • Pastoralism 

    • Stall-feeding

    • Intensive farming

    • Extensive farming 

    • Large scale farming 

    • Small scale farming

    The facts

    a) Monocropping

    This is the type of farming system whereby a single crop is grown on a large area. The farmer only grows one type of crop on the same piece of land throughout the farming season. In Rwanda, tea, coffee, potatoes, sugarcane and pyrethrum are the main crops planted using the monocropping system.

    Advantages of monocropping

    (i) Operations like weeding, disease and pest control and harvesting are easily carried out.

    (ii) It is easy to mechanise field operations.

    (iii)There is optimum utilisation of applied fetiliser and manure as a result of correct plant population establishment.

    Disadvantages of monocropping

    (i) Continuous growing of one crop may lead to depletion of a particular nutrient resulting in low crop yields. (ii) It encourages build-up of pests and diseases.

    (iii)It is difficult to control parasitic weeds on the crop, for example, the Striga spp in maize crops.

    (iv) In cases of crop failure, heavy losses are incurred.

    (v) There may be little profit realisation in cases of reduction in prices in the market.

    (vi) Lack of soil cover encourages erosion especially when crops that grow upwards are planted continuously.

    b) Intercropping

    This involves the growing of two or three crops in association. All the crops are planted on the same piece of land. Examples of combinations of crops that can be grown using this system are maize, beans and finger millets. Intercropping can also be referred to as interplanting.

    Activity 1.11: Research Activity

    Research on other crops that can be interplanted and list them down. What are the benefits of these?

    Advantages of intercropping

    (i) There are high crop yields per unit area.

    (ii) It ensures ample soil cover especially when cereals are interplanted with legumes. This minimises soil erosion.

    (iii)There is no total loss in cases of disease and pest outbreaks. It is hence an insurance against total loss.

    (iv) There is supplementation of nutrients in the soil especially when legumes are included.

    (v) Some plants can even act as nurse crops for other crops. An example is the maize crop which acts as a nurse crop for bean plants.

    (vi) Maximum utilisation of soil nutrients is ensured particularly when deep rooted plants are interplanted with shallow rooted plants.

    Disadvantages of intercropping

    (i) Carrying out of field practices, such as weeding, pest and disease control becomes difficult.

    (ii) It is not possible to mechanise the various field operations.

    (iii)There is wastage of fertiliser since some of the crops planted may not respond to some given types of fertilisers. It will therefore require the farmer to apply different forms of fertiliser in order to cater for all the types of crops planted.

    (iv) Use of herbicides becomes impossible since it may cause harm to some of the crops planted.

    c) Pastoralism

    Pastoralists are people who depend on livestock or the sale of livestock products for most of their income and for consumption. In this system, the livestock is mainly grazed on communally-managed or open-access pastures, and where there is at least some propensity of households or individuals to move seasonally with livestock. This is not common in the Rwandan culture.

    d) Stall-feeding

    This involves keeping and feeding an animal in a stall, especially with an aim of fattening it. It is also known as zero grazing. Rwanda is one of the most densely populated countries in Africa. With this condition every effort must be made both to increase agricultural output and to protect the soil from erosion. One of these efforts is to encourage stall feeding among farmers.

    The idea of stall-feeding also enables production of manure for composting. The compost manure is used in the farms to increase the organic content of the soil. This helps to increase the permeability of soil and also improve the soil’s water storage capacity, hence raising soil fertility, increasing yields and reducing erosion.

    1. Draw a model of stall-feeding and give examples of livestock that can be kept under stall feeding.

    2. How does stall feeding help small scale farmers?

    3. What are the advantages of intercropping over monocropping?

    e) Extensive farming

    This system of farming involves use of large portions of land, normally with low capital, labour and management investment. There is also very minimal mechanisation. Extensive farming is mostly carried out in marginal areas and wastelands.

    Advantages of extensive farming

    (i)   It is cheap due to low capital input.

    (ii)  It requires less labour input.

    (iii) It leads to proper utilisation of marginal areas and wastelands.

    (iv) It does not require high level management skills.

    Disadvantages of extensive farming (

    i)  It has low output due to the low investment in capital, labour and management skills.

    (ii)  The land is under-utilised; in terms of the available nutrients. (

    iii) It cannot be practised in densely populated areas since it requires large portions of land. (

    iv) It has low profit per unit area. This is because of the small amount of output obtained.

    f) Intensive farming

    The system is characterised by the use of a lot of labour, large sums of capital investment and high level management skills. In this system, agricultural mechanisation is practised and irrigation can also be applied where necessary. A good example of a farming method that applies intensive farming is horticultural farming; which usually results in high returns per unit area

    Advantages of intensive farming

    (i) There is maximum utilisation of land.

    (ii) It can be practised in areas that are densely populated.

    (iii)Due to the high level management skills involved, the intensive farming system often gives high yields and high quality produce.

    (iv) It results in high income and high net revenue (profit).

    Disadvantages of intensive farming

    (i) In the event of failure-due to poor or ineffective management, or disease/pest attack, heavy losses can be incurred.

    (ii) High initial capital is required.

    (iii)High labour costs are incurred.

    (iv) It requires high levels of skills and management.

    g) Large scale farming

    This entails the growing of crops and keeping of livestock in large hectares of land (usually over 20 ha). Large scale farming is mainly done for commercial purposes. Field operations are normally mechanised especially during land preparation, and in some cases, during planting and harvesting. Large scale farming can either be intensive or extensive.

    Advantages of large scale farming

    (i) It results in high yields.

    (ii) The farmer can take advantage of the economies of scale to increase profits.

    (iii)It promotes foreign exchange earnings for the country.

    (iv) It helps to create employment opportunities owing to the large labour force required where mechanisation is not possible.

    Disadvantages of large scale farming

    (i) A huge sum of capital investment is required for the purchase of farm inputs and machinery.

    (ii) A lot of labour force is required, especially where mechanisation is not possible. This is for instance in coffee and tea harvesting.

    (iii)High level management skills are required in order for good profits to be realised.

    (iv) Heavy losses can be incurred in the event of disease and pest attack.

    (v) It can only be practised where there are large tracts of land.

    h) Small scale faming

    Unlike in large scale farming, small scale farming is the growing of crops and keeping of livestock in a limited area of land. It is characterised by very minimal mechanisation. Most small scale farmers rely on their families for labour. During high seasons, casual labourers can be hired to supplement the family labour. Due to limited arable land, the majority of farmers in Rwanda are small scale farmers. Small scale farming can be practised both for commercial purposes and also for subsistence purposes. It can also either be extensive or intensive.

    Discussion corner!

    Discuss about some of the reasons that can lead farmers to being small scale farmers.

    The facts

    Conditions that lead to small scale farming include:

    (i) Lack of adequate land

    (ii) Limited capital for large scale farming

    (iii)Lack of market or incentives

    (iv) Government policies

    Advantages of small scale farming

    (i)   It requires low capital investment.

    (ii)  It has low labour requirement.

    (iii) The farmer can decide to sell surplus produce to generate income for the family.

    Disadvantages of small scale farming

    (i)     It has low output per unit area due to low investments in input and management.

    (ii)   It is less profitable compared to large scale farming.

    (iii)  The marketing of produce is difficult and unprofitable.

    Self-evaluation Test 1.5
    1. Which farming system is the most economical and why?

    2. Which farming system ensures maximum utilisation of land and how?

    3. Of the farming systems, which one ensures high output and why?

    4. Which farming system requires high level management and why?

    5. Which of the farming systems do you think is the most appropriate for upcoming farmers? Why is this the case?

    Remember the facts! • Agriculture is the art and science of cultivating land, growing crops and rearing livestock. • In Rwanda, the agricultural sector accounts for about 90% of the national food needs and it generates more than 70% of the country’s export revenues.

    • Agriculture has various branches. These include: 

    - Soil science  - Crop husbandry 

    - Animal husbandry 

    - Agricultural economics 

    - Agricultural engineering 

    - Horticulture

    • Farming systems are ways in which farm enterprises are organised and utilised. 

    • Types of farming systems include: 

    - Monocropping 

    - Intercropping 

    - Pastoralism 

    - Stall-feeding 

    - Extensive farming 

    - Large scale farming 

    - Small sale farming

    Test your competence 1

    1. Explain how agriculture affects human life.

    2. Why is Agriculture a popular practice in Rwanda?

    3. Discuss the various types of farming systems you have learnt about in terms of: 

    (a) The number of crops grown. 

    (b) The kind of product targeted.

    4. Why would you spread awareness to your community against encroaching into forests so as to acquire land for agriculture?

    5. What are some of the problems that farmers in your area face and what are the possible solutions you can give for these problems?

    6. How would you recommend the structure of your school farm to be improved so that it becomes more effective?

    7. (a) Which are the most commonly planted crops in your school farm and why? 

    (b) Which farming system is being used to plant those crops in your school farm?

    (c) Do you think the farming system being employed is appropriate? Give reasons for your answer.

    8. Choose the single word used to describe growing of vegetables.

    A. Floriculture

    B. Pomoculture

    C. Arboriculture

    D. Olericulture

    9. For horticultural farming to be successful there has to be a good transport system, electricity and high level farm management skills. Justify this statement.

    10. Why do you think intensive farming is the most appropriate for horticultural farmers?

    11. Referring to the branches of Agriculture, point out those that relate to the following subjects and also explain how they relate. 

    (a) Physics 

    (b) Chemistry 

    (c) Home science 

    (d) Biology 

    (e) Economics

    12. What do we call the type of farming where crops are grown and livestock are reared in large tracts of land?

    A. Extensive farming

    B. Intercropping 

    C. Large scale farming

    D. Pastoralism


    • Agricultural practices are carried out on soil. This means we rely on land to do agriculture. It is therefore important for us to understand soil and its composition. Look at the pictures below. They show various types of soil. Which type of soil do you know? Which soil is suitable for farming?

      This unit is about soil and its importance in Agriculture.

      Key Unit Competency

      After studying this unit, I should be able to interpret soil formations, soil properties and the various types of soil.

      Unit Outline

      2.1 What is soil?

      2.2 Soil formation

      2.3 Types of soil

      2.4 Components of soil

      2.5 Soil profile

      2.6 Properties of soil

      2.7 Soil sampling and testing

      2.1 What is soil?

      Activity 2.1: Research Activity

      1. Find out the definition of soil and how it is formed. You can use the internet search engine and other reference books in the library.

      2. Present your findings in class.

      I have discovered that…

      Soil refers to the loose natural material which form the uppermost layer of the earth’s crust. Formation of soil from the parent material is referred to as soil genesis.

      The facts

      Soil is very important in our lives. It provides anchorage, nutrients and water to plants. The top soil, in particular, covers most of the earth’s surface. It forms the fertile soil which contains minerals, organic matter and living things. It is good for farming. For this reason, this layer forms the basis of agriculture.

      Self-evaluation Test 2.1

      1. How does soil support plant growth?

      2. What is top soil?

      3. What are some of the components of soil?

      2.2 Soil formation

      Activity 2.2

      1. Your teacher will show you a video on how soil is formed.

      2. From what you have seen in the video, note down the processes of soil formation. Describe how they happen and write a report. Present your findings to the rest of the class.


      I have discovered that…

      Soil is formed by weathering of rocks through various physical, biological and chemical processes. The rock from which soil is formed is referred to as the parent material or parent rock. Minerals particles form the main bulk of soil. The organic portion of the soil forms a small but very important part.

      The facts

      Weathering refers to disintegration of rock particles to form soil. It takes several hundreds of years for a centimeter of soil to be formed. The weathering process is brought about by physical, biological and chemical agents. It is in turn influenced by climate changes, parent rock material, living organisms, topography and time. All these are referred to as soil formation factors.

      The process of soil formation

      Soil formation, or soil genesis, takes place through a process called weathering. Weathering is the breaking down and alteration of the parent rock near the surface to form soil. The various forms of weathering include:

       • Physical weathering 

       • Biological weathering  

      • Chemical weathering 

       • Transport and deposition

      a) Physical weathering

      Physical weathering, also known as mechanical weathering, involves disintegration of rocks into smaller fragments by physical agents. The agents include climatic factors such as rainfall (running water), temperature changes, moving ice (glaciers) and wind.

      (i) Wind - When strong wind blows, it carries rock materials from the ground. These materials bounce on the ground and hit against each other hence breaking off into smaller fragments which form soil.

      (ii) Rainfall (running water) - When it rains, the raindrops hit the ground with some force making rock particles to be loosened and broken down. Running water also carries small stones which hit against each other along the river bed or on the ground surface resulting in further breaking off and wearing out of rock particles. This is how alluvial soils are formed and deposited on river banks; and in later stages on river plains.

      (iii) Moving ice (ice glaciers) - Moving ice also known as glacier, depending on its size, has the capacity to cause rocks to rub over each other as they are carried along the ground. This causes breakdown of rock particles into small pieces. In other words, glaciers have a grinding effect on rock surfaces.

      (b) Biological weathering

      Biological weathering involves the disintegration of rock and minerals due to the chemical and physical agents or organisms. Living organisms play a very important role in soil formation through various biological processes. Living organisms here act as agents of weathering. For example, when large animals such as cattle, buffaloes, camels, elephants and human beings move, they exert pressure on the rocks causing small fragments of rock to disintegrate. Also, animals moving in large herds are very effective in breaking rocks or stones to form soil.

      Physical activities of human beings such as mining, cultivation, quarrying and construction of buildings, railways and roads on the earth’s surface reduce the size of rocks into smaller particles.


      Fig. 2.6: Quarrying cause breaking of rocks to form soil

      Organisms living in the ground, including moles and earthworms, burrow the soil and break large soil particles into smaller pieces.  In the course of their living, organisms produce fluids or wastes which have chemicals that can cause corrosion.  Body fluids of most organisms contain ammonia, carbon dioxide and hydrogen.  When these come into contact with rock surfaces in the presence of water, they cause substantial corrosion. Roots of growing plants, on the other hand, penetrate small cracks in rocks and exert considerable pressure which eventually causes breakage of rocks. When these plants die, the roots decay leaving gaps in the rocks which are then occupied by water and air.  These form acids which dissolve minerals from rocks and corrode the rocks weakening them so that they are easily broken into fragments by other agents of weathering. Roots produce acids in the soil during respiration. These acids dissolve minerals from rocks.

      (c) Chemical weathering

      Discussion corner!

      What do you know about corrosive chemicals? Name them. Explain how they act.

      Rocks which form the parent material where soil comes from are made up of chemical substances which in the course of time undergo changes that alter the composition of rocks.  Chemical weathering is the actual decay or decomposition of rocks.  It involves various chemical reactions which take place between rock minerals, water and certain atmospheric gases like oxygen and carbon dioxide. Chemical weathering changes the chemical structure of the rock, making it unstable hence easy to disintegrate. Chemical weathering involves the following processes.

      (i) Carbonation - This term describes the action of carbon dioxide on rock minerals.  Carbon dioxide can dissolve in water to form a weak carbonic acid.  This acid can dissolve some of the rocks, especially marble and limestone.

      The resulting calcium bicarbonate is easily broken down since it is soluble in water.  Therefore, limestone parent rocks form soils by this chemical weathering process.

      (ii) Oxidation - This means the taking up of oxygen present in the air by an element or compound.  It is important to note that oxygen also oxidises many elements. It usually occurs in compounds which contain mainly iron and sulphur. The oxides which are formed take up more space and help in rock disintegration. For example, oxygen oxidises iron from olivine rocks into ferrous oxide, ferric oxide and red ferric oxide producing red soils.

      (iii) Hydration - This occurs when water combines with minerals present in the rocks. It causes softening of the original rocks, making them easy to break. The chemical composition of the rocks however, remains unchanged.  When dehydration occurs, on the other hand, the rocks often revert to their original forms.

      (iv) Dissolution - Water can dissolve any soluble minerals present in the rocks. When this occurs, the minerals that hold the rocks together are dissolved and the rocks easily disintegrate. For example, in areas where there is a lot of industrial smoke being produced, the gases produced dissolve in water to form corrosive substances which can weather rocks. Some of the industrial gases produced are sulphur dioxide, hydrogen among others. When these gases dissolve in water, they form weak acids. These acids cause rocks to be brittle hence ready to weather physically.

      (v) Hydrolysis - This occurs when the minerals in the rocks react with water. Chemical bonds in the minerals are broken by water, changing rocks from their original forms and making them easy to break. Hydrolysis best occurs where there is free movement of underground water.

      (d) Transport and deposition (accumulation)

      Wind acts as a transport agent and hence it can carry the weathered materials from one place to another.  Where a lot of weathering materials are deposited, there are deep soils. However, where the materials were carried from will be left bare or with very shallow soils. Bacteria and fungi initiate breakdown of plant materials on the surface and within the soil. Also, arthropods such as mites, springtails and termites are chiefly responsible for more severe breakdown of plant tissues.  Termites and earthworms mix organic matter with mineral fractions of the soil.

      Self-evaluation Test 2.2 
      1. Which human activities in your area do you think lead to soil formation?

      2. How can we encourage soil formation and still discourage soil erosion?

      2.3  Types of soils

      Activity 2.3

      Field trip

      1. Go for a field excursion in your neighborhood, or any appropriate place, and collect the various types of soil samples.
      2. Describe the various types of soils you will have gathered.

      3. Distinguish the various types of soils by touching (feel the various soil samples in between your fingers) and note down your inferences and conclusions. Use a table format.

      The facts

      The most common types of soils are clay soil, loam soil and sandy soil.

      (a) Clay soils

      Properties of clay soil

      (i) They have more than 50% clay particles  and between 0-45% silt and sand.

      (ii) They have a very high water holding capacity but their ability to release this water to plants is much less compared to that of loam soil. This hence makes it difficult to cultivate crops in clay soils.

      (iii) They are fine textured and smooth.

      (iv) Clay usually forms extremely hard clods or lumps when dry and is extremely sticky and plastic when wet.

      (v) They have a crystalline and platy structure and expose a relatively large surface area which is responsible for their physical and chemical properties.

      (vi) Clay soil has poor aeration and drainage but high capillarity. When wet, the clay particles expand and this impairs drainage.  It therefore, makes them become heavy causing tillage operations difficult and expensive.

      (vii) When containing the proper amount of moisture, it can be made into ribbons by squeezing between thumb and forefinger.

      (viii) They have high nutrient absorption ability. This increases the amount of nitrogen causing the soil to have pH that is between neutral and alkaline.

      (ix) Tubers and plant roots grown in such soils are greatly affected in their growth when the soil becomes dry.

      (x) Lack of moisture may lead to hastened maturity in plants, making them yield less than expected.

      (xi) The rate at which clay soils absorb water is low. Water therefore accumulates on the surface making them to be waterlogged.  They can be improved by drainage.

      (xii) This class of soil is particularly good for growing cotton and rice.

      (b) Loam soils

      Properties of loam soils

      (i) These are medium–textured soils which contain 30–50% sand particles, 40% silt and 20% clay, with about 4% of organic matter.

      (ii) They have good proportions of sand and clay in their composition.

      (iii) They are the most productive soils for crop production as they contain good amounts of plant nutrients and organic matter.

      (iv) They are high in soil water available for plant use and have a good water-holding capacity.

      (v) They are easy to till and do not erode as easily as sand soil, hence most crops do well in loamy soils.

      (vi) These soils can be improved by planting cover crops to maintain fertility and also by adding manures and fertilisers.

      (c) Sandy soils

      Properties of sandy soils
      (i) Sandy soils generally contain 80%
        sand particles, 10% silt and 10% clay
        and about 3% of organic matter.

      (ii) They are usually well drained, coarse
        textured and moderately fertile.

      (iii) They have a low water-holding capacity
        and capillarity, hence cannot retain
        enough water for plant use.
      (iv) These soils are more prone to erosion than either clay or loam soils. This is mainly because sandy soils have a less stable structure on the surface.

      (v) Deep rooted plants suited for arid regions can survive on sandy soils.

      (vi) They are easy to cultivate but are not fertile.  However, they can be improved by adding a lot of organic manure and fertilisers.

      Self-evaluation Test 2.3

      1. Describe the type of soil in your area.

      2. (a) Do you think the soil in your area is good for farming?

        (b) Which types of crops should be planted?  Why?

      2.4  Soil components

      Discussion corner!

      What do you think soil is made up of? Talk to your friend about this. Write a report and present it to class.

      Soil constituents refer to the components that make up soil. They include the following:  • Mineral particles/inorganic matter or rock particles 

       • Soil water  

      • Soil air  

      • Organic matter (humus) 

       • Soil living organisms

      The facts

      (a) Mineral particles/inorganic matter Mineral particles are also referred to as inorganic matter. 

      It forms the main framework of soil in which plants anchor their roots. The inorganic matter of the soil is made up of particles of rocks formed from parent rock by the weathering process. The mineral constituents of these depend on the mineral composition of the parent rock from which it was derived. There are spaces between the particles which are filled with air and water.

      Activity 2.4

      Finding out the sizes and shapes of particles of various types of soil Collect various soil samples from different places and observe them using a handlens or under a light microscope. Describe their shape. Draw the shapes in

      your notebook. Compare and contrast the sizes of the particles. Comment on their suitability for use in growing crops.

      The structures, texture and colour of the mineral particles are derived from the minerals found in the parent rock. Various soils are composed of particles of various sizes and shapes as shown below.

      (b) Soil water

      Activity 2.5

      Finding out if soil contain water

      Apparatus/ materials

      • A lump of soil

      • Transparent plastic containers with leads

      • Hand lens Procedures

      Procedures

      1. Dig out a lump of soil from a random  

      2. Put the lump of soil in a transparent plastic container with a lid.

      3. Place the container out in the sun and leave it for about 6 hours.

      4. Observe the sides and lid of the container.

      Discussion corner!

      1. What do you see?

      2. Why was the observation made? location in your school compound.

      The facts

      Soil contains water which comes from precipitation (rainfall) or through irrigation. The amount of water in the soil is determined by factors such as the rate of precipitation, evaporation rate, the amount and type of vegetation cover, the water storage capacity, temperature, gradient of the land, type of soil and altitude. Basically soil water exists in three forms, namely:

      • Superfluous water 

      • Capillary water 

      • Hygroscopic water

      (i)  Superfluous water  This is water that exists in the large air spaces (macro-pores) between the mineral particles. It is held by gravitational force and can be made available to plants for use through the roots.  This water is easily lost because it is loosely held by soil particles.  Its amount varies inversely with the amount of air available. It is important to note that this water is not very useful to plants. Too much of it in the soil limits aeration and it also drains away a lot of nutrients hence causing leaching.

      (ii)  Capillary water  This is underground water available to plants through the roots and occupies the micropores.  It is held with greater force by soil particles.  It dissolves plant nutrients.  It is also referred to as the available water since it leaves most of the macro-pores empty to allow aeration of the soil. 

      (iii) Hygroscopic water  This is water held strongly by the soil particles and exists as a thin film around the soil particles.  This water is subject to forces created by soil particles and therefore it is not available to the plant.  However not all soil particles have hygroscopic water. For instance sandy particles with weaker forces contain very little hygroscopic water whereas clay particles have a lot of hygroscopic water.

      Activity 2.6:

      Finding out the percentage of water in a soil sample

      1. Come up with a procedure to demonstrate the percentage of water in a given sample of soil. Your teacher may provide you with the following apparatus:  • Soil sample  

      • A porcelain dish  

      • Bunsen burner  

      • Stirring rod 

       • Desiccators  

      • Weighing balance  

      • Tripod stand  

      • Wire gauze  

      2. Record the steps you will need to follow, your results and conclusions.

      3. Write a report and do a presentation to the rest of the class on your findings.

      The facts

      Sample procedure for investigating the percentage of water in a soil sample

      1. Collect a sample of garden soil from a depth of about 20 cm.

      2. Weigh the empty porcelain dish and record the weight.

      3. Put some of the soil in the porcelain dish and weigh.

      4. Heat the dish with its content in an oven at a temperature of about 105°C for about 1 hour.

      5. While heating, the soil sample in the dish, it should be stirred to facilitate complete moisture evaporation.

      6. The soil sample should be heated until a constant weight is obtained.

      The results of the procedure can be recorded as shown below:

      • Weight of empty dish =  (a) gm

      •  Weight of fresh unheated soil =  (b) gm

      • Weight of dish + fresh unheated soil =  (a + b) gm

      • Weight of dish + heated soil =  c g

      • Weight of evaporated water = (b – c) gm Percentage of water in the soil can be calculated using this formula:

      I have discovered that…

      Soil contains a certain percentage of water; hence water forms a substantial proportion of soil.  However, the quantity of water in soil varies with different soils. For instance, sandy soil contains much less water compared to both clayey and loamy soils.

      The facts

      The following are importances of soil water: 

      (i) Water serves as a solvent for the plant nutrients (minerals) in the soil.

      (ii) It is an essential raw material used in the process of photosynthesis by plants.

      (iii) It is taken in by plants as a coolant in the process of transpiration.

      (iv) Most of the protoplasm in plant cells is made up of water.  It makes the plant cells turgid.  The movement of this water within the plant cells makes the plant to stand upright (erect).

      (c) Soil air

      The air content of soil consists of oxygen, carbon dioxide, nitrogen and other rare gases. Soil air is located in soil pores separated by soil particles. The content and composition of soil air is determined to a large degree, by soil–water relationships. Air simply moves into the soil pores that are not occupied by water.

      The amount of air in the soil is inversely proportional to the amount of water in the soil pore spaces. The pore size and distribution is influenced by soil texture and structure. The air in soil has remarkable influence on plant growth and soil organisms; especially for respiration of plant roots. The presence of air in the soil leads to oxidation, which converts part of organic matter into nitrates; a form readily available to the plants. When there is less oxygen in the soil, some plants may not do well. This is because their roots are not able to absorb water from the soil.  Excess carbon dioxide in the soil can cause harm to plant roots. A good soil for crop growing must contain an adequate amount of air. The air must circulate freely and continuously in order to keep oxygen at a level high enough for proper plant growth. For instance, there must be a balance between soil water and soil air for most crops to do well.  It is important to note that the nitrogen in the soil must be converted into nitrates by the nitrogen–fixing bacteria for it to be available for plant use.

      Activity 2.7

      Determining the presence and percentage of air in soil

      1. Find out how to establish the percentage of air in a soil sample. Your teacher may provide you with the following apparatus:

       • A small tin (of known mass)  

      • A large graduated glass  

      • Trough 

       • Stirring rod 

       • Ruler  

      • A knife  

      • 500 cm3 graduated cylinder  

      • Hammer 

       • A nail 

      2. Record the steps you will follow, your observations and conclusions.

      3. Write a report and make a presentation to the rest of the class.

      The facts

      Sample procedure for investigating the presence (percentage) of air in a soil sample

      1. Fill a tin of known mass, for example a 300 g jam tin, with water and transfer the water into the 500 cm3 cylinder.

      2. Then fill the tin with garden soil and use a ruler to cut clean the soil in the tin so that it fills just up to the brim.

      3. Place the tin with soil carefully into the water in the graduated cylinder. The tin should be placed upside down without pouring the soil out.

      4. Record the final volume of the soil and water in the cylinder.

      Note: It is important to note that the volume of the soil in the tin is equal to the volume of the tin.  This experiment could be repeated with different soil types such as clay and loam.

      5. Put some soil in glass of water as shown below. Note your observations

      I observed the following:

      • When the small tin with soil was placed in the water the level of the water rose. • Bubbles of air were also seen escaping from the small tin through the holes at the base of the tin. • While the bubbles were escaping the level of the water was dropping.

      The results of the procedure can be recorded as shown below:

      Volume of soil in cylinder = (a) cm3

      Original volume of water in the cylinder = (b) cm3

      Volume of soil and water in the tin = (a+c) cm3

      New volume of soil after air has escaped = (c) cm3 

      Percentage of air in the soil can be calculated as shown below:

      I have discovered that…

      Soil contains a certain percentage of air. Hence air is a component of soil. The percentage of air in any given soil depends on the type of soil.

      The facts

      The following are the importance of air in soil: 

      (i) Air is required for plant respiration.

      (ii) Oxygen in the soil combines with many elements in the soil so that they become available to plants.  For example oxygen combines with nitrogen to form nitrates which are used by plants.

      (iii) Plants and animals that occupy spaces in soil require oxygen for respiration.  These organisms are useful in the process of soil formation.

      (d) Soil organic matter

      Soil organic matter is derived from partially decayed and totally decomposed plant and animal remains. Organic matter that has totally undergone decomposition is called humus. Humus may be dark or brown in colour and is very rich in plant nutrients.  It is usually found at the top of the soil profile. Due to its dark colour, humus absorbs and retains a lot of heat. Therefore, soils rich in humus are relatively warm.

      The process of breaking down organic matter releases carbon dioxide into the atmosphere. Other substances such as sulphates (SO4)2-, phosphates (PO4)2-, nitrates (NO3)- and other nutrients are oxidised and released into the soil for plant use. Humus also cointains important minerals such as calcium (Ca2+), magnesium (Mg2+), potassium (K+) and ammonium (NH4)+ ions which are released to plants for their nutrition. It is important to note that a good supply of humus in the soil increases the amount of water absorbed and its availability in the soil.

      Activity 2.8

      Determining the percentage of organic matter in soil

      1. Come up with a procedure to find out the percentage of organic matter in various soil samples. Your teacher may provide you with the following materials and apparatus:

       • Silica dish/porcelain dish 

       • Fresh garden soil  

      • Weighing balance 

       • Tripod stand  

      • Bunsen burner  

      • Wire gauze  

      • Stirring rod  

      • Desiccator  

      2. Record the steps you will have followed and your results.

      3. Write a report and do a presentation to the rest of the class.

      The facts

      Sample procedure for investigating the presence (percentage) of organic matter in a soil sample

      1. Weigh the empty silica dish and record the mass.

      2. Collect fresh samples of garden soil from a depth of about 20 cm where there is a high likelihood of getting a good supply of humus.

      3. Put the collected soil sample in the dish and record the mass.

      4. Heat the soil sample in an oven at a temperature of about 105°C for two hours.

      5. Allow the moisture in the soil to evaporate.

      6. Cool the sample in desiccator-this is to prevent more moisture from being added into the soil.

      7. Weigh the cooled soil sample and record the new mass.

      8. Heat the cooled soil sample strongly over a Bunsen burner noting any change in appearance of the soil during the heating process.  The heating will remove the humus in the soil, converting it to gases. The gases then escape into the atmosphere.

      9. Cool the dish and soil sample in the desiccator. 10. Weigh it and record the new mass. (Note:This heating, cooling and weighing is repeated until a constant weight is obtained.)

      The results of the procedure can be recorded as shown below:  

       • Mass of silica dish = (a) g  

      • Mass of fresh soil  = (b) g  

      • Mass of burnt soil = (c) g  

      • Mass of strongly burnt soil = (d) g 

      • Mass of humus removed     = (c – d) g  

       • Percentage of humus in the soil can be calculated as shown below:

      I have discovered that…

      There is always a percentage of humus in a given soil sample. Hence soil contains organic matter or humus.

      The facts

      The following are the importance of organic matter in soil:

      (i) It is a major source of most plant nutrients such as nitrates, phosphorous, sulphur and calcium.

      (ii) Organic matter provides food for micro-organisms in the soil. These microorganisms promote the process of soil formation.

      (iii) Organic matter in the soil absorbs moisture and acts as a sponge, resulting in moisture retention.

      (iv) Organic matter binds soil particles together. It helps to maintain the structure, workability, aeration, water penetration and increases the water holding capacity of the soil.

      (v) Organic matter has a texture that helps increase the water holding capacity especially in sandy soils.

      (vi) The dark colour of humus makes it absorb and retain more heat in the soil thereby moderating soil temperature.

      (e) Soil living organisms

      Living organisms are a very important component of the soil. In fact, soil contains a variety of living organisms. They range from micro-organisms such as bacteria and fungi to insects, earthworms and rodents. These micro-organisms live in the micro-pores in the soil particles whereas the larger organisms burrow into the soil. When, larger organisms such as earthworms burrow into the soil, they make it well aerated and loose. On the other hand, micro-organisms such as bacteria, fungi and protozoa help in the decomposition of organic matter. Some bacteria, such as those of the rhizobium group, live in the roots of leguminous plants. They help in converting soil nitrogen into nitrates. These nitrates are later absorbed by plants. However, some of these micro-organisms may damage crops by causing diseases. Examples are bacterial and fungal diseases that attack crops.

      Activity 2.9

      Determining the presence of living things in a soil sample

      1. Come up with a procedure of an experiment to show presence of living organisms in soil. Your teacher may provide you with the following apparatus and materials:  

       • Fresh garden soil   

      • Porcelain dish   

      • 2 conical flasks   

      • Rubber corks   

      • Bunsen burner   

      • Strings   

      • 2 muslin bags   

      • Lime water   

      • A tripod stand

      2. Record the steps you will follow, your observations, reasons and inferences.

      3. Write a report and do a presentation to the rest of the class.

      The facts

      Sample procedure for investigating the presence of living organisms in a soil sample

      1. Collect a sample of fresh garden soil.

      2. Place half of the collected soil on a porcelain dish and heat it until you are sure that all the living organisms are dead. Then let it cool.

      3. Place the other half of the fresh garden soil in a muslin bag and suspend in the first conical flask containing lime water as shown in Fig. 2.14 A.

      4. Place the heated soil in another muslin bag and suspend it in another conical flask which has lime water as well. See Fig. 2.14 B.

      5. Leave the set up to stand for about 4 hours then make your observations


      I have observed that:

      Lime water in conical flask A turns milky while lime water in conical flask B remains clear.

      The lime water in conical flask A turns milky because living organisms present in fresh soil exhale carbon dioxide during respiration. This is what forms the white precipitate when it comes into contact with lime water.

      The lime water in conical flask B remains clear. This is because the soil living organisms in that soil sample were burnt to death during heating; hence no carbon dioxide was present to turn the lime water milky.

      What I have discovered!
      • Garden soil usually contains living organisms which respire actively. • These organisms take in oxygen and exhale carbon dioxide. 
      Importance of living organisms in the soil

      (i) Living organisms help in soil formation by physically breaking down the soil particles.

      (ii) The micro-organisms assist in the decomposition of organic matter in the soil.

      (iii) The larger organisms on the other hand burrow the soil and in the process they aerate it.

      (iv) Certain micro-organisms such as the rhizobium bacteria help fix free nitrogen in the atmosphere into nitrates. This makes it available to plants.

      Self-evaluation Test 2.4 

      1. Given the following information: 

      Weight of empty dish = 15 gm

      Mass of dish + fresh soil = 45 gm

      Mass of dish + heated soil = 40 gm Calculate: 

      (a) Mass of unheated soil only. 

      (b) Mass of heated soil only. 

      (c) Mass of evaporated moisture. 

      (d) Percentage of water in the soil.

      2. Given the following information: 

      Mass of silica dish + fresh soil = 36 g

      Mass of silica dish + burnt soil = 35 g

      Mass of silica dish + strongly burnt soil = 33 g 

      Calculate the percentage of humus that was in the original soil sample.

      3. What is the significance of soil living organisms in the soil?

      4. Why would it be important to establish the percentage of organic matter in a soil?

      2.5 Soil profile

      Activity 2.10(a)

      Field trip

      1. Go out into the field. With the help of your teacher, find a hole that has been recently dug. Observe, from the wall of the hole the various layers of soil. You can also visit a quarrying site to observe these layers.

      2. Make a drawing of what you have seen in your notebook.

      3. Back in your class, compare the layers you drew with the chart provided by the teacher. Did you get the layers right?

      I have discovered that…

      Soil profile is the vertical arrangement, or a cross-section of soil layers from the ground level (surface) to the parent rock.  These layers are known as horizons. The horizons differ in properties such as colour, texture, structure, porosity, organic matter content and chemical composition.

      The facts

      Soil profile can help to determine whether the soil is mature or recently formed. This depends on the number of horizons present. From the soil profile, we can also determine the origin of the parent material involved in soil formation. Every soil type has its own way of formation. The horizons in a soil profile are:

       • Top soil  

      • Subsoil  

      • Substratum (weathered rock)  

      Characteristics of the horizons in the soil profile

      (i)   Horizon A (Top soil)

      This is the uppermost soil layer which lies beneath the superficial layer (surface) and marks the beginning of the mineral soil. It is commonly known as the top soil.  It is characteristically dark in colour due to its high humus content. It is well aerated and contains active living organisms which break down and decompose organic matter into humus. Most plant roots and nutrients are found here. This zone is permeable to air and water and it is also well-drained.

      (ii)  Horizon B (Subsoil)

      This is the layer found immediately below the top soil (Horizon A) and is also referred to as subsoil.  Tap roots of large plants reach to this layer. The base of this layer is more compact and less aerated than their top soil. It also contains an impermeable layer called a hard pan. This hard pan impedes drainage and may prevent root penetration.  There are clay deposits in this zone because of the downward movement of clay colloids.  Sometimes minerals are leached from the subsoil and accumulate here, hence the subsoil layer is also referred to as layer of accumulation.

      (iii) Horizon C (Substratum or weathered rock)   

      This layer is also referred to as substratum or weathered rock.  This layer is found beneath the subsoil and is partly made of weathered rock with no humus.  Tap roots of large trees may reach this layer and draw water from it during the dry season.  The layer is hard, therefore impermeable to water.  During erosion, most parts of the horizon A and B are washed away to expose this layer.

      (iv) Horizon D (Bedrock)

      This layer is found below the weathered rock and is also referred to as the parent rock or bedrock.  This layer is completely impermeable to water and air.  Soil is formed from this rock.  The entire soil profile is from this horizon.  Water table is found in this layer.

      Activity 2.10 (b)

      Having learnt about the various layers of soil, refer to the diagram you drew in Activity 2.10(a) and label it (name the various layers you have learnt about correctly). Recognise the most important layer and explain why it is important.

      Influence of soil profile on crop production

      a) The suitability of a soil for agricultural production can be determined by the depth of the soil profile.  Farmers look at how deep the soil profile is to decide what crops to grow and how best to cultivate the land.

      b) Soils on steep slopes have their top fertile layers washed away. This type of soil has very thin or shallow top layers. Erosive agents especially water can easily wash it away. This makes such soils less fertile and they therefore cannot support growth of healthy plants.

      c) A deep soil having a well developed profile has great potential for agriculture. It is able to hold more moisture for plant use than a shallow one.

      d) A loosely packed subsoil layer allows easy penetration of roots, drainage and aeration.  It also ensures that erosion does not take place and reduces the degree of run-off. This layer must also be fairly deep. The maintenance of the top soil and subsoil ensures that fertile soils are available for plant growth.

      e) Most of the soil nutrients are contained at the top soil. This is vital to plants since most soil organisms, such as soil microbes and plant roots spread here.

      f) The top soil is usually better aerated. It has therefore more active microorganisms which decompose the vegetable matter into humus.

      g) The nature and composition of the mineral components of the bedrock have influence on the mineral components of the whole soil. Thus the mineral nutrients that a soil is able to supply to the plant largely depends on the mineral composition of the parent rock. If, for example, the parent rock lacked in some minerals, then the soil formed from it will also lack those same minerals.

      h) Crop production is influenced by root penetration into the subsoil and by the amount of moisture and nutrients held there. An impermeable subsoil will restrict root growth and penetration.

      i) The topography on which the soil develops greatly influences its properties. Soils that develop from slopes have shallow horizons A and B than soils developing from level topography.  Soils on level grounds are darker in colour than soils on steep slopes.

      Self-evaluation Test 2.5

      1. Explain how we can ensure that soil profile is well maintained.

      2. How important is the top soil to plant growth?

      2.6 Soil properties

      Soil properties can be explored from three perspectives. They include:  • Physical properties  

      • Chemical properties  

      • Biological properties 

      a) Physical properties of soil

      Activity 2.11

      Collect various soil samples from different areas in your locality. For each of the samples:

      1. Observe the colour and record.

      2. Pass the soil particles in between your fingers to feel how smooth or rough they are and record.

      3. Use a hand lens or light microscope to observe how the aggregate soil particles look like. Draw the shapes of the various soils in your notebook.

      What I have discovered The physical properties of soil include:  

      • Soil colour  

      • Soil texture 

       • Soil structure

      The facts

      (i) Soil colour

      Soils tend to have distinct variations in colour when looked at horizontally and vertically as well.  This property can help identify the nutrients in the soil. It also gives information on the present condition of the soil system. Soil colour is determined by the minerals present in the parent rock, the amount of organic matter and the amount of iron in the soil.  If a soil was formed from a rock containing a lot of iron compounds, it tends to be brownish or reddish in colour. Such soils are rich in oxidised iron.

      Soils rich in organic matter are usually black in colour. This is due to the presence of humus and other substances in the soil such as peat and more or less decomposed plant residues. The amount of water present may also determine the type of reactions that take place in the soil. It may also determine the colour of the soil. For example, soils which have a lot of water are poorly drained and they tend to develop a greyish colour. In arid areas, soils develop a high concentration of solute salts. They do not have organic matter and are generally whitish-yellow in colour. The combination of iron dioxide and organic content gives many soil types a brown colour. It is important to note that soil colours influence soil temperature. Dark soils absorb and retain more heat than light coloured soils.  High temperatures affect the activity of soil micro-organisms.  Soil micro-organisms will be more active in high temperatures. Under such conditions, the decay of organic matter is usually faster than it is in low temperatures.

      (ii) Soil texture

      The term soil texture refers to the relative proportions of the various sizes of mineral particles in soil. More appropriately, soil texture is a term commonly used to designate the proportionate distribution of the different sizes of mineral particles in a soil.Soil texture can also be defined as the coarseness or fineness of a soil sample when felt between fingers.  Some particles are large and therefore coarse in texture while others are small.  The small particles are fine to the feel between the thumb and the index finger hence giving a fine texture.

      Soil textural classification

      Most soils do not consist entirely of particles of the same size.  Most soils are a mixture of sand, silt and clay particles.  The texture of the soil determines its ability to absorb and retain water and soil nutrients. The following are the classes of soil according to their texture: • Clay soil

      • Sandy clay

      • Sandy loam

      • Clay loam

      • Loam soil

      • Silty loam

      • Silty clay These classes can be obtained using the textual triangle see fig 2.16. Follow any two component percentages to find the name of the soil type.For example, for a soil that is 75% silt and 50% clay. Find 50% along the bottom (clay) line. Follow the slanted (dotted) line until you reach the horizontal line for 75%. The soil type is clay loam.

      Activity 2.12

      Demonstrating that soil is made up of differently sized particles

      1. Come up with an experiment to demonstrate that soil is made up of differently sized particles. Your teacher may provide you with the following materials and apparatus:  

      • Garden soil  

      • Water  

      • Sodium carbonate  

      • A 250 cm3 measuring cylinder

      2. Record the steps you followed, the observations and results you obtained.

      3. Write a report and do a presentation to the rest of the class.

      The facts

      Sample procedure for investigating the sizes of various soil particles

      1. Collect fresh garden soil.

      2. Put about 50 g of the soil in the 250 cm3 measuring cylinder.

      3. Add sodium carbonate about four times the volume of water to help in dispersion of the soil particles.

      4. Cover the mouth of the cylinder with your hand and shake vigorously for about two minutes.

      5. Place the cylinder on the bench for about one hour or more to allow the contents to settle down.

      I observed that…

      The soil in the cylinder settles in various layers as shown in figure 2.17 below.

      • The heavy, coarse gravel settled first.

      • Followed by sand, silt and clay.

      • The humus and other organic matter remain floating on the water. 

      • The depth of each layer can be assessed by reading from the marks on the measuring cylinder.

      I have discovered that…

      Garden soil is a mixture of particles of different sizes.

      Activity 2.13

      Determining size of particles of different types of soil

      1. Perform an experiment to determine size of particles of different types of soil. Your teacher may provide you with the following apparatus and materials:  

      • Sieves of different mesh diameters 

       • Garden soil 

       • Containers  

      • Weighing balance 

      2. Record the steps you followed, the observations and the inferences made. 

      3. Write a report and do a presentation to the rest of the class.

      The facts

      Sample procedure of an experiment to determine sizes of different soil types

      1. Collect fresh garden soil.

      2. Place a known amount of soil into a container.

      3. Crush the soil lumps without breaking the particles.

      4. The crushed soil should be passed through the sieve with the largest mesh diameter (2.00 mm) and shaken vigorously.

      5. Observe the sizes of the soil particles that remain on the sieve and record.

      6. Repeat the process using the other sieves with mesh diameters of 0.2 mm and 0.02 mm (always using the soil that passes through the previously used sieve).

      I have observed that…

      Some larger soil particles are always left on the different sieves used. The soil particles left on the first sieve of mesh diameter 2.00 mm are called gravel; from the second sieve (0.2 mm), coarse sand particles; from the third sieve (0.02 mm), fine sand particles; from fourth sieve (0.002 mm), silt particles and whatever particles pass through the smallest sieve (0.0002 mm) are clay particles.

      Note: The proportions of the various soil particle sizes can be calculated based on the original mass of soil sample.

      I have found out that…

      • Soil is made up of differently sized particles. • Gravel particles are fairly large and heavy because they contain a lot of iron. • Sand particles are coarse textured and are very well aerated. When wetted and felt between the fingers, sand particles are coarse and gritty.

      • Silt particles are smooth and powdery. 

      They normally increase the water holding capacity of the soil. Therefore the higher the amount of silt in a soil, the greater the amount of water available for plant use in that soil. • Clay particles are fine and colloidal in nature hence their rate of water absorption is very good.  Clay particles are closely packed together and contain very small and few air spaces. They feel smooth, sticky and plastic when wet and can easily be molded. They form very hard lumps when dry. Such particles remain suspended in water for a very long time.

      Activity 2.14

      Determining the water-holding capacity of a given soil 

      1. Carry out an experiment to find out the water-holding capacity of various soil samples. Your teacher may provide you with the following apparatus and materials:  • Measuring cylinders   

      • Funnels    

      • Water 

      • Cotton wool 

       • Sandy soil 

      • Clay soil  

      • Loam soil  

      • Stop watch

      2. Record the steps you will have followed, your results and conclusions. 

      3. Write a report and make a presentation to the rest of the class.

      The facts

      Sample procedure for investigating the water holding capacity of various soil samples 

      1. Dry the soil samples in the sun.

      2. Crush all the soil samples except sandy soil.

      3. Plug the funnels with equal amounts of cotton wool.

      4. Place equal amounts of the three different types of soil into each of the funnels.


      5. Place each funnel onto a separate measuring cylinder as shown above, and then quickly pour 20 cm3 of water into each of the funnels. (The water should be poured into each of the funnels simultaneously as a fourth learner starts the stop watch.)

      6. Record the time taken for any known volume of water to drain through each of the soil types in each measuring cylinder. (Once the stop watch has been stopped, the funnels must be removed from each of the measuring cylinders so that no more water drains in. Label the respective measuring cylinders with the type of soil).

      7. Note the volume of water collected from each set up. In which soil was most water collected?

      I observed that…

      • After about half a minute, the first drop will come from the funnel containing sandy soil. • In the funnel containing loam soil, the first drop was seen after about one minute while the first drop from clay soil took about five minutes to drip into the measuring cylinder.

      Conclusion

      • Clay soil is least porous of the three types of soil while sandy soil is the most porous. • It can also be said that sandy soil has low water-holding capacity while clay has the highest water-holding capacity.

      • Loamy soil has an average porosity and water-holding capacity.

      • Soils found in low-lying areas and depressions which are characterised by dull colours and fine textures usually range between imperfectly drained and poorly drained.

      Activity 2.15

      Comparing capillarity in different soils

      1. Come up with an experiment to compare the capillary action of different soils. Your teacher may provide you with the following apparatus and materials:  

      • Long capillary tubes  

      • Trough 

       • Water  

      • Samples of sandy, clay and loamy soils 

       • Cotton wool  

      • Stop watch  

      • A ruler 

       • A clamp 

      2. Note down the steps you followed, and the observations and inferences you made.

      3. Write a report and do a presentation to the rest of the class.

      The facts

      Sample procedure for an experiment to compare the capillarity  action of different soils

      1. Collect the three types of soil, sandy, clay and loam and ensure they are adequately dried.

      2. Crush the loam and clay soil samples to fine particles except the sandy soil.

      3. Plug one end of each capillary tube with cotton wool.

      4. Put the samples of sand, loam and clay soils labelled A, B and C respectively in separate capillary tubes. 5. Using a clamp, hold the tubes upright in the water trough as shown in Fig 2.20.

      6. Put water into the trough to a depth of 5 cm.

      7. Remove the tubes from the trough after about 3–5 minutes and measure the height of water in every tube.

      8. At least six readings should be taken.

      9. Leave the experiment to stand overnight. Examine the height to which the water has risen in each kind of soil after 24 hours.

      10. Plot the results on a graph; mark the time in minutes along the horizontal axis and water height in centimeters along the vertical axis.

      11. Plot the graphs for each of the three samples on the same axes.

      Note: By comparing the three graphs, we can deduce the relationship of size of soil particles to capillarity action represented by the height of the water.

      I observed that

      • After some time, water rose up through the three tubes by capillarity action. The water rose fastest in clay soil followed by loamy soil within the first few minutes. After about 2 hours, the level of water in the clay soil was highest followed by loam soil and then sandy soil. • The water stopped rising first in sandy soil and it stopped rising last in clay soil. Conclusion

      • Clay soil has the highest capillarity of the three soil types. • Loam soil has average capillarity. It is therefore good for crop production. • Sandy soil has the lowest capillarity.

      (iii) Soil structure

      Soil structure refers to the physical appearance of soil in terms of how the individual soil particles are arranged, packed and aggregated. It is a term used to describe the overall arrangement or grouping of soil particles. Aggregated soil consists of many soil particles held or cemented together. They form natural units of compound
      particles/clusters or aggregates. The consistency of the soil changes with the amount of water present in the soil. Soil aggregates are often separated from adjoining surfaces by lines of weaknesses. When a soil sample is dry, its consistency is described as loose, soft, hard or very hard. When moist, its consistency is loose, friable or firm. Wet soils are sticky and plastic. This is especially true of clay soils. Soil organic matter is important in soil aggregation due to its binding effect.

      Types of soil structures

      Activity 2.16

      Go out into the field and collect soils from different places. (Be careful not to crush the soil samples). Label the soils depending on where they were obtained. Carry the soil samples carefully back to class. Observe the soil under a hand lens. Draw the various shapes of soil structures observed. Comment on the shapes of the structures and where the soil sample was obtained.

      The facts

      There are various types of soil structures. They are categorised according to the arrangement of the particles and the pore spaces in the soil. Soil structure depends on the kind and extent of aggregation. Aggregation is influenced by climate, living organisms, topography, parent material and time. Clay particles and humus influence soil structure by the way they cement or build the different soil particles into bigger and more stable aggregates. Secretions from plant roots may influence soil structure as well. The most common types of soil structures are:  

      • Crumb soil structure  

      • Granular soil structure  

       • Single–grained soil structure  

      • Prismatic and columnar soil structure  

      • Platy (plate-like) soil structure 

       • Block soil structure

       (a)  Crumb soil structure

      The soil particles here appear irregular in shape, small and rounded. They are not closely fitted together; that is the soil particles loosely adjoin with other aggregates. This soil is therefore soft, porous and permeable, yet it retains moisture. They are normally found on horizon A.

      (b)  Single–grained soil structure

      This is an elementary structure which forms no aggregates meaning that particles are not cemented together.  This structure is relatively non-porous with small and spherical particles mostly found at the top soil of sandy soils, arid climates and alkaline soils.

      (c) Granular soil structure

      The soil grains appear irregular in shape and aggregates are rounded with smoother edges.  The aggregates are loosely held together and when wet, the grains are highly porous. This is because the spaces in between are not readily closed. This structure can be found in the top soil horizon of cultivated soils and in the subsoil horizons of soils under grasses or bushes. The granular soil structure is the only arrangement influenced by practical methods of tillage. It contains organic material and a high water retention capacity.

      (d)   Platy soil structure

      The aggregates here appear in thin horizontal plate-like layers. It is actually a soil structure whose aggregates are arranged on top of one another in relatively thin horizontal plates, as in leaflets. The plates often overlap and impair permeability. This impedes drainage and root penetration. Soils with such structures are poorly drained and are not suitable for growing crops. The structure is mostly found at the top horizon of soils in forests and it is mainly found in clayey soils.

      (e)   Prismatic structure 

      The soil particles in this structure are cemented in vertically oriented pillars. The tops of the pillars could be shaped in such a way that they are level, plane and clean cut. This is what gives the structure the name prismatic.  Soils with such a structure are normally located in the subsoil horizons of arid and semi-arid lands.

      (f)   Columnar structure 

      When soil aggregates are arranged vertically but with flat rounded tops, they are said to have a columnar structure. The columns are similar to those in the prismatic soil structure; apart from the rounded tops. They are also found in the subsoils of arid and semi arid areas.

      (g)   Block soil structure

      The aggregates are arranged in rectangular blocks. The aggregates easily fit together along vertical edges. They make penetration of plant roots difficult because their angular edges fit closely. They are moderately permeable, poorly aerated and drained. The blocky structure is common in finely textured subsoils.

      Activity 2.17
      Having learnt about the various soil structures, refer to the ones you had drawn in Activity 2.16. Identify and name the various soil structures you had drawn.

      Influence of soil structure on crop production

      • A good soil structure ensures a good balance between soil water and air since soil structure influences the pore spaces in the soil. In fact the amount of air and water present in a soil sample depends on the pore spaces available.  This implies that soils with closely packed particles are poorly aerated and drained. • A good soil structure aids drainage thereby avoiding waterlogging.  Remember that most crops do well in well aerated and drained soils except for a few such as rice, which do well in waterlogged soils. • A good soil structure also ensures adequate water retention for the plants. 

      It also reduces accumulation of carbon dioxide in the soil through proper aeration. • Use of heavy machinery on wet soils destroys the structure thus decreasing permeability and aeration.  This results in high incidences of surface run-off and erosion.

      • Soil structure influences the water-holding capacity of a soil. A good soil should hold enough water for plant use.  A soil which cannot retain water, though fertile, may not be good for crop production as there will be no water available for plant use. • Soil living organisms respire and produce carbon dioxide which must be removed from the soil so that it does not build up to toxic levels.  This is facilitated by free circulation of air. The structure should allow free circulation of air by having enough pore space, which can be occupied by air as in granular or crumby soil structures. In such soils, the plant roots and microorganisms can get the oxygen they need while carbon dioxide is expelled easily. • Waterlogged soils may result from structures whose particles fit closely together. For example soils with platy structure have a higher capacity for holding water, hence such structures may be good for crops such as rice.

      b) Chemical properties of soil

      Chemical properties of soil are influenced by the following factors:  

      • The level of organic matter in the soil  

      • The amount of rainfall or precipitation  

      • The mineral rock from which the soil particles have been derived On decomposition, organic matter in the soil releases organic acids, like carbonic and nitric acids, which make the soil acidic. In high rainfall areas, soils tend to be acidic due to excessive leaching of bases like potassium hydroxide, calcium hydroxide and magnesium hydroxide. Soils derived from rock particles rich in minerals, such as aluminum, are usually acidic.

      The four major chemical properties of soil include:

       • Soil pH  

      • Salinity  

      • Cation Exchange Capacity (CEC)  

      • Carbon: Nitrogen ratio 

      (i)   Soil pH 

      Soils may generally be referred to as either acidic or basic. One of the most important chemical properties of soil is pH. Soil pH is a measure of the degree of acidity or alkalinity of a soil solution. It is expressed as the potential hydrogen, which is the hydrogen ion (H+) concentration in a soil solution. 

      Soil pH can be measured in two ways:  

      • Using a universal indicator solution: This solution results from the mixing of several acidic-base indicators put together. When this is added to a soil solution, the colour change is matched with the colours on the pH chart.

       • Using a pH meter: This is a device used to determine the pH of a soil solution. The equipment is expensive and may only be found in agricultural laboratories.

      The pH scale shown above runs from 0–14 corresponding to hydrogen ion concentration with pH 7 being the neutral point. The values in the pH scale that fall above 7 are alkaline while those less than 7 are acidic. This means that the lower the pH, the more acidic a soil solution is; that is solutions with low pH values are strongly acidic while those with high pH values are highly alkaline.

      Activity 2.18

      Determining soil pH using the Universal indicator

      1. Conduct a research in the library or by using the internet and find out how the universal indicator solution is used to determine soil pH. Note down your findings.

      2. Having known how the Universal Indicator solution is used, come up with an experiment to determine the pH of various soil samples. Your teacher may provide you with the following apparatus:   •     Test tubes  

       •     Universal indicator solution  

       •     A pH chart  

       •     Barium sulphate powder  

       •     Soil samples  

       •     Distilled water 

      3. Record the steps you will follow, the observations and readings, and note down the inferences you make. 4. Write a report and share with the rest of the class members.

      The facts
      A sample procedure for determining the soil pH of various soil samples:

      1. Place the soil samples in different test tubes to a height of about 1 cm.

      2. Add an equivalent amount of barium sulphate to the test tubes containing the soil samples-this helps to ensure flocculation and precipitation of colloidal clay.

      3. Fill the test tubes with distilled water to about 4 cm from the top.

      4. Shake the test tubes thoroughly.

      5. Allow the contents to settle; then add 8–10 drops of the universal indicator solution.

      6. Shake the test tubes again and allow the contents to settle.

      7. Hold each of the test tubes against the pH chart.

      8. Compare each colour on the pH chart with the colour of the suspension and note the pH of the colour which matches it most closely.


      I have discovered that…

      Various soil samples collected from different places have varying pH values. Various plants also have preferences for soils with specific pH values.

      (ii) Salinity  Soil

      salinity refers to the concentration of salts in a soil solution. This can be pronounced at the top soil surface. Salt solutions can move to the top soil surface by capillarity from the salt laden water table. They then accumulate due to evaporation of water. Salt can also accumulate due to human activities, such as use of potassium fertilisers, which accumulates phosphate salts. As soil salinity increases, it results in soil degradation.

      Activity 2.19

      Determining soil salinity using a salinity meter

      1. Perform the experiment below to determine the salinity of soil in an area of your choice. You may be provided with the following apparatus:   

      •     Soil sample    

      •     Distilled water  

       •     Weighing scale  

       •     Measuring cylinder  

       •     Jug or any container   

      •     Salinity meter 

      2. Follow the steps below: 

      (i) Take a sample of soil and leave it to dry in the sun.

      (ii) Crush the soil lumps after drying. Use a wide and heavy blunt object, such as a hammer.  

      (iii) Place 50 g of the dried soil in the jug and add 250 cm3 of distilled water. 

      (iv) Shake the content vigorously for about 3 minutes to enable salts in the soil to dissolve in the water. 

      (v) Allow the solution to settle for at least 1 minute. 

      (vi) Place the salinity meter in the solution and read the display.

      Note: Do not dip the salinity meter into the soil settled at the bottom of the container. Soil salinity can also be tested by use of a conductivity meter.

      3. Carry out research on the internet and find out how the conductivity meter is used.

      Note down the steps to follow and use it to measure soil salinity. (The conductivity meter will be provided by your teacher.)

      (iii) Cation exchange capacity of soil (CEC) 

      Cation exchange capacity of a given soil refers to the total capacity of a soil to hold exchangeable cations.  Factors influencing Cation Exchange Capacity of soil 

      • Nature of clay minerals in the soil-for example a CEC increases with the amount of clay and it also varies with the type of clay.

       • Texture of soil-that is finer textured soils have more mineral colloids than coarse textured ones. 

      • Organic matter – the higher the humus content the higher the CEC. The type of humus compound is also important. For example, humus which has been developed from monocotyledonous leaves are better.  • Soil pH – The higher the soil pH, the higher the CEC.

      Note:

      • The availability of a certain cation to plants will depend very much on the proportion of that cation in the cation exchange capacity of the soil. 

      • The replacement of cations by others is known as cation exchange.

       Importance of Cation Exchange Capacity of a soil (CEC) 

      • Cation Exchange Capacity of a soil is described as a measure of how much nutrients a soil can hold rather than how fertile a soil is.  However, it is very much correlated with natural soil fertility because it indicates the degree of weathering.

       • CEC guides a farmer on the level of fertilisers and liming to apply.  Nutrients should be applied to the soil in amounts which the soil can hold not in big surpluses which will leach away without being taken up by plants. 

      • On the other hand a soil with a high CEC requires high fertiliser application and or liming before nutrients can be available to plants.

      (iv) Carbon: Nitrogen ratio

      Carbon is an essential constituent of all living things. It occurs naturally in the atmosphere in form of carbon dioxide whereby it constitutes 0.03% of air by volume. Atmospheric carbon dioxide is the major source of carbon required by plants. The various processes contribute to the circulation of carbon in the atmosphere. These processes include those that use carbon from the atmosphere and those that replenish carbon into atmosphere.
       Nitrogen is one of the most important elements needed for plant growth.  It occurs naturally in the atmosphere in form of nitrogen gas (N2); it constitutes 78% of air by volume.  However, it is not available to plants in this free gaseous form. The various processes which contribute to the circulation of nitrogen in the atmosphere include those that use nitrogen from the atmosphere and those that replenish nitrogen into the atmosphere.
       Therefore, the Carbon: Nitrogen ratio through its selective influence on soil organisms, exerts a powerful control on nitrification and the presence of nitrogen in the soil. The nitrogen in the soil may be used by the soil microorganisms and higher plants, or it may as well be lost through leaching, or it may escape into the air in volatile form. For purposes of encouraging the useful microbial activity in the soil, it is important to maintain a good balance of the C:N ratio in the soil.

      (c) Biological properties of soil

      Living organisms are found almost everywhere on earth.  These living organisms have both positive and negative effects on their surroundings. Living organisms may include pests, parasites, decomposers, pathogens, predators, pollinators and nitrogen-fixing bacteria. The main soil micro-organisms you shall learn about in this section are bacteria.  The following are the two major categories of bacteria that are important in soil:

       • Symbiotic bacteria – Found in nodules of leguminous plants such as beans. They mainly include rhizobium bacteria.  

      • Non-symbiotic bacteria – Found in the soil which include azotobacter bacteria.

      Apart from decomposing organic matter, bacteria perform other useful functions like fixing free atmospheric nitrogen into the soil for plant use. This is done by the rhizobium bacteria. Nitrogen is converted into nitrates which are absorbed by plants. Some micro-organisms damage crops by causing bacterial and fungal diseases in plants. Nematodes live as parasites in plant roots and interfere with the nutrient and water uptake.  Clostridium and azotobacter are two genera of anaerobic soil bacteria that are dependent on plants for their activities. They can fix atmospheric nitrogen to nitrogenous matter. When these micro-organisms die, they decompose and release the nitrogen compounds into the soil for use by crops.  On the other hand, soil nitrogen may also be lost in form of ammonia, nitrogen gas or oxides of nitrogen. This may be due to the activity of certain denitrifying anaerobic bacteria which can oxidise ammonium on to ammonia gas; nitrates and nitrous acid are reduced to nitrogen and oxides of nitrogen such as nitrogen oxide.

      Self-evaluation Test 2.6

      1. How does the soil in your area behave when it rains? What does that say about its water-holding capacity?

      2. Why should a prospective farmer be keen on investigating the properties of soil in a land he/she is intending to cultivate first before embarking on any farming?

      2.7 Soil sampling and testing

      Soil sampling is the process of random collection of a small quantity of soil from a defined area of land. The soil then acts as a representative sample for laboratory testing and analysis.  The defined area of land where the sample is taken from is known as a sampling unit. Such a chosen area should be uniform in terms of slope, drainage, soil texture, soil colour, fertiliser usage and history of cropping. Soil is sampled in order to be tested for nutrients and soil pH. An analysis of the samples gives information about the fertility status of the soil. In fact, sampling should be done when crops show deficiency symptoms or whenever yields start to drop.

      (a) Soil sampling methods

      There are two methods of soil sampling which are usually used:

      • The traverse method

       • The zigzag method 

      (i)  The traverse method  This is where the sampling follows a line along diagonals of the field or a sampling unit. It is also referred to as the diagonal method.

      (ii) The zigzag method  This is where the sampling forms random zigzag patterns in the sampling unit.  Here locations are arranged in such a way that they are in a zigzag form as shown below.

      When sampling, the following areas should be avoided: 

      • Places where manure or organic matter have been heaped  • Fence lines or boundaries which may not give representative sample. 

      • Places near trees  

      • Swampy areas  

      • Dead furrows 

       • Footpaths in the field  

      • Ant-hills in the field  

      • Areas between slopes and the bottom line

      Soil sampling procedure

      When collecting a soil sample the following procedure should be followed carefully in order to get reliable results and a good representative sample.

      1. Clear sampling unit of any vegetation by scrapping it off.

      2. Make a vertical cut to a depth of 15-25 cm for crop land and 5 cm for top soil and 25-30 cm for subsoil.

      3. Take a slice from the vertical cut, preferably using a soil auger.

      4. Put the soil obtained from each site, for both topsoil and subsoil layers, in a clean container.

      Note: The above steps can be done on 10-20 sites depending on the sampling method being used.

      5. Remove any foreign materials from the collected soil samples.

      6. Dry the soil samples and crush them into smaller particles or colloids.

      7. Use the quartering technique to arrive at a small quantity of each representative sample.

      8. The samples should then be packed in sampling envelopes and dispatched to the laboratory with the following information given:  

      • Name and address of the farmer or locality of the farm  

      • History of fertilisers or manure use     

      • Crop to be grown 

       • History of land use 

       • Special features on the land  

      • Date of sampling

      Activity 2.20

      Perform a soil sampling procedure on your school farm. Record your results and present them in class.

      (c) Soil pH

      Soil pH, as we have seen previously, is a measure of the degree of acidity or alkalinity of a soil solution.

        Testing soil

      pH From our previous discussions, we saw that soil pH can be determined accurately. We only used the Universal indicator solution as one method of testing for soil pH. However, here we shall explore more ways of determining soil pH. It is important for farmers to understand the pH status of soil in their prospective and even present pieces of land to avoid disappointments. The following are some alternative methods of determining soil pH.

      (i) Using a pH meter

      The pH meter is an expensive equipment only found in research stations, colleges, universities and some teacher training colleges.  This method is also known as glass electrode method.  The pH meter consists of a thin-walled bulb of special glass which contains dilute hydrochloric acid, into which a platinum wire is dipped to make an electrical contact.

      This arrangement is sensitive to the hydrogen ion concentration of the solution to which it is immersed.  The pH meter method is accurate. However, the set up is expensive hence it is only limited to research work.

      Using colour indicators


      In soil pH testing, the colour indicators that can be used include the following:

      • Litmus paper

      • Universal indicator papers (pH papers)

      • Colour indicator dyes Some of the procedures of determining soil pH using colour indicators are outlined below.

      (i) Universal indicator method

      1. Place a little soil on clean porcelain plates.

      2. Pour 1–2 cm3 of the indicator on the soil.

      3. Wash the soil with the indicator and allow the liquid to drain away from the soil into a clean part of the porcelain.

      4. The colour of the solution is observed against the pH colour chat and the acidity or alkalinity of the solution estimated.

      (ii) Using universal indicator papers

      1. A small quantity of soil sample is taken and added to about 25 cm3 of distilled water which has been boiled to expel dissolved carbon dioxide.

      2. The mixture is shaken thoroughly and a piece of the pH paper is then dipped.

      3. The colour change of the pH paper is checked against the pH chart to give the correct pH value.

      (iii) Using a commercial soil testing kit

      • A small quantity of soil sample is taken and shaken with distilled water to make a soil solution. • A few drops of commercial indicator are added to the solution. • The colour of the soil solution is then compared with the colours on the colour chart.

      Note: The basis of this method is the fact that different indicators change colour at different pH values.

      (iv) Using litmus papers

      Although litmus papers can also be used, they only indicate whether a solution is acidic or alkaline and cannot give specific pH values. Remember that use of litmus papers is the simplest pH testing method. The litmus papers exist in two colours; blue to test for acidity and red to test for alkalinity. If the solution is acidic, blue litmus paper turns red, while the red litmus paper remains red. If the solution is alkaline, the blue litmus paper remains blue while the red litmus paper changes to blue. Litmus paper colour remains the same in neutral solutions. The limitation of this method is that the pH value is not known.

      Self-evaluation Test 2.7

      1. Select three areas that should be avoided during soil sampling and justify why they should be avoided.

      2. Which method or instrument of determining soil pH is the best according to you and why?

      Remember the facts!

      • Soil refers to the loose natural material on the uppermost layer of the earth crust.

      • Formation of soil from the parent material is known as soil genesis. • Soil is formed by weathering of rocks through various physical, biological and chemical weathering processes.

      • The common types of soils are clay soil, loamy soil and sandy soil. 

      • The quantity of water in any soil sample depends on the type of soil it is.

       • Soil contains a certain percentage of air. Air is a component of the soil. • Humus is normally made up of organic matter. • Soil usually contains living organisms which respire actively. • We should avoid burning soil and using harmful chemicals on soil. These might cause harm to the soil living organisms. • Soil profile is the vertical arrangement or a cross-section of soil particles in different layers from ground level. The layers of the soil profile are called horizons.

      • Physical properties of soil include: 

       − Soil colour 

       − Soil texture  

      − Soil structure 

      • Soil is made up of particles of different sizes. 

      They include:  

      − Gravel: fairly large and heavy.  

      − Sand: coarse-textured and very well aerated.  

       Silt: smooth and powdery.

       − Clay: fine and colloidal. • Soil structure refers to the physical appearance of soil in terms of how the individual soil particles are arranged, packed and aggregated. • Soil pH is a measure of the degree of acidity or alkalinity of a soil solution. 

       • Various plants have preferences for specific pH values. 

      • Cation exchange capacity (CEC) of a given soil refers to the total capacity of a soil to hold exchangeable ions.

      • Soil sampling is the process of random collection of a small quantity of soil from a defined area of land. The soil will then act as a sample for laboratory testing and analysis.

      Test your competence 2

      1. Explain what happens during soil genesis in your own words.

      2. Distinguish between the three types of soils described in this unit and give the appropriate uses of each type.

      3. (a) How does the water-holding capacity of a soil relate with texture? 

      (b) How does this affect crop farming?

      4. Explain the factors which determine the amount of soil water in any given type of soil.

      5. We must avoid burning soil and using dangerous chemicals on it. Explain why.

      6. Explain some of the activities which you think can lead to increased soil salinity.

      7. How does carbon:nitrogen ratio affect plant growth?

      8. Which activities do you think can destroy the physical soil structure and how?

      9. (a) Why is sandy soil more erodible than clay soil? 

      (b) What are some of the things you can do to prevent soil erosion?

      10. Mutesi has just acquired a piece of land which she plans to cultivate. However, the piece of land is largely dominated by sand soil. Explain what advice you would give Mutesi so that she can improve the soil fertility of the piece of land.

      11. Which soil structure is likely to encourage waterlogging?

      A. Single-grained soil structure

      B. Platy soil structure

      C. Crumb soil structure

      D. Granular soil structure


      • TOPIC AREA 2: CROP AND MUSHROOM PRODUCTION AND PROCESSING

        Unit 3: A farm

        In agriculture, there are so many tools and machines that can be used to facilitate various agricultural activities. Each of the agricultural tools and implements are usually used for specific operations. These tools can be used both during crop production and livestock production. All of them have an important role to play in the improvement of agricultural operations.

        Discussion corner!

        Look at the photographs below. Can you say what is going on in the photographs? What would happen if the tractors were not used? What impact would that have on farm productivity?

        This unit is about farm tools and machines. It should empower you to use and appreciate farm tools and machines in your daily life.

        Key Unit Competency

        After studying this unit, I should be able to:

        a) Classify farm tools.

        b) Use small farm tools safely.

        Unit Outline

        3.1 Identifying small farm tools.

        3.2 Categories of farm tools, their uses and maintenance practices.

        3.1 Identifying small farm tools

        Activity 3.1

        1. Go for a field trip to a multipurpose farm and find out why farmers use farm tools.

        2. Observe the various farming tools used. Find out how they are used, their names, types and classes.

        3. Draw the tools you have seen at the farm in your note book.

        I have discovered that…

        Some of the reasons why farmers use farm tools and equipment are:

        (i) To increase efficiency and to make farm operations easier.

        (ii) To minimise injuries to farm animals. This mostly applies to livestock production tools.

        (iii) To enhance production process.

        The facts

        Some common farm tools are given in Table 3.1. Which ones do you know?

        3.2 Categories of farm tools, their uses and maintenance practices

        Activity 3.2

        1. Find out the names of the farm tools in Table 3.1.

        2. Categorise the tools as either farming tools or gardening tools.

        3. Discuss the uses and maintenance practices of each of the tools. Note them down and present them in class.

        The facts

        The two major categories of farm tools are:

        • Gardening tools 

        • Farming tools

        A. Gardening tools These are small farm tools used for carrying out general gardening activities. This mostly entails crop production at a very small scale level. These gardening tools include the following:

        (i) Machete

        It is mainly used for cutting down small trees and grass used to feed livestock. It is also used to clear land before cultivation.

        Maintenance practices    

        • Store properly in the tool store. 

        • Paint the metallic part to prevent rusting during long periods of storage.

        • Repair worn out or broken handle. 

        • Sharpen when blunt using of a file.

        (ii) Axe It is used for:

        (i) Cutting tree stumps.

        (ii) Felling big trees during initial stages of land preparation.

        (iii) Splitting trees into logs for construction of farm structures and firewood.

        Maintenance practices

        • Replace worn out handles. 

        • Paint the metallic part to prevent rusting. 

        • Store properly in the tool store. 

        • Sharpen regularly to maintain efficiency. 

        (iii) Pick axe It used for:

        (i) Digging out stony grounds and hard soil. 

        (ii) Uprooting tree stumps before ploughing.

        (iii) Cutting tree roots during land preparation.

        Maintenance practices

        • Replace the handle when worn out.

         • Paint the metallic part to prevent rusting. 

        • Proper storage in the tool store. 

        • Fix loose handle properly. 

        (iv) Digging hoe (hand hoe)

        It is used for:

        (i) Cultivation of land when preparing seedbed and during weeding.

        (ii) Digging foundations of farm structures and buildings.

        (iii) Preparing planting furrows and holes.

        Maintenance practices

        •   Regular cleaning after use. 

        •   Proper storage in the tool store. 

        •   Paint the metallic part to prevent rusting.
        • Sharpen regularly to maintain efficiency. 

        • Replace incase of broken handle. 

        (v) Wheelbarrow

        It is used for transporting small loads like sand, bags of seeds or seedlings (during transplanting), bags of fertiliser, among others within a short distance.

        Maintenance practices    
        • Tighten loose nuts and bolts.

        • Grease or oil the wheel and moving parts to facilitate smooth running of the wheel.

        • Apply old engine oil or paint the metallic part to prevent rusting.

        • Store properly under a tool shed. 

        • Repair any worn out or broken parts. 

        (vi) Rake

        It is used for:

        (i)  Collecting uprooted plant roots and stems when      preparing a nursery seedbed for vegetable crops.

        (ii) Breaking large soil clods, removing stones and other      rubbish to obtain a fine tilth for tiny seeds.

        (iii) Leveling and finishing of the seedbed.

        • Paint the metallic part to prevent rusting. 

        • Replace any worn out or broken handles. 

        • Repair any broken or bent teeth. 

        • Store in a cool store.

        (vii) Tape measure

        It is used for measuring distance and length

        Maintenance practices

        • Proper storage in the tool rack. 

        • Clean the tape in case it comes into contact with dirt. 

        (viii) Garden trowel

        This is a pointed scoop-like tool. It is used for:

        (i)   Loosening the soil.

        (ii)  Digging small shallow holes.

        (iii) Lifting out seedlings from the nursery bed during transplanting.

        Maintenance practices

        • Store properly in the tool rack. 

        • Apply old engine oil to prevent rusting.

         • Clean after use. 

        • Replace broken wooden handles. 

        • Ensure it is firm. 

        (ix) Garden fork It is used for:

        (i) Weeding nursery or carrot fields.

        (ii) Preparing holes for transplanting seedlings. 

        Maintenance practices

        • Repair any broken handles. 

        • Store properly in a tool shed. 

        • Paint the metallic parts to prevent rusting. 

        (x) Watering can

        It is used for watering seedlings in seed boxes, potted plants, nursery beds and transplanted seedlings.

        Maintenance practices

        •   Clean after use.

        •   Paint the body (tank) to prevent rusting (for metallic watering cans).

        • Remove the rose, unblock the perforations and return in place. 

        • Proper storage in the tool store. 

        • Repair leaking tank and any other damaged parts, such as the handle

        (xi) Shovel

        It closely resembles the spade, but it has a tray-like blade. It is used for scooping loose soil, fertilisers, seeds and sand.

        Maintenance practices

        • Replacing worn out handles. 

        • Applying oil on the metallic parts to prevent rusting.

        • Store properly in a dry place. 

        (xii) Slasher

        It is used for clearing shrubs.

        Maintenance practices

        The handle must be well fixed and the blade must be kept sharp.

        (xiii) Billhook

        It is used for cutting banana leaves.

        Maintenance practice

        The handle must be well fixed and the blade must be kept sharp. 

        (xiv) Grafting knife

        Used for grafting woody plants.

        Maintenance practices

        • The blade must be well fixed on the handle. 

        • The blade must be kept sharp.

         • The blade must also be painted to reduce rusting. 

        (xv) Secateurs

        It is used for pruning crops like coffee and cutting flowers. (Pruning involves cutting unwanted branches and suckers.)

        Maintenance practices    

        • Replace broken handles.

         • Paint the metallic parts to prevent rusting.

         • Store properly in a tool cabinet.

         • Grease or oil the pivot for easy movement. 

        • Replace the worn out parts.

         • Sharpen the edges. 

        (xvi) Leveling board

        It is used for leveling a prepared seedbed especially in rice fields.


        Maintenance practices

        • Clean after use. 

        • Store properly in a tool rack. 

        Activity 3.3: Research activity

        1. Find out other garden tools that are not in this list.

        2. Give their uses and maintenance practices.

        3. Discuss with your group members and do a class presentation of your findings.

        B. Farming tools

        These are tools used for performing various farming activities. These activities may entail both crop production and livestock rearing. The following are some examples of farming tools.

        Note: Some gardening tools can as well be used as farming tools.

        (i) Forked hoe             

        It is used for:

        (i) Removing underground perennial weeds, such as couch grass.

        (ii) Digging hard, stony, wet or muddy soils.

        (iii) Harvesting tuber crops such as Irish potatoes.

        Maintenance practices

        • Clean after use. 

        • Oil the metallic parts to prevent rusting. 

        • Replace broken handle. 

        • Straighten bent prongs. 

        (ii) Spade It is used for:

        (i) Digging in place of a hoe, for instance in coffee plantations where use of a hoe may damage coffee roots. (ii) Removing soil when digging holes and applying manure. 

        Maintenance practices

        • Clean after use. 

        • Store properly in the tools store. 

        • Apply oil on the metallic parts to prevent rusting. 

        • Replace any broken handles. 

        (iii) Spring balance          

        It is used for weighing farm produce and farm inputs like seeds.

        Maintenance practices

        • Proper storage in the tool rack. 

        • Paint to prevent rusting. 

        • Lubricate the inner springs by applying oil or grease.

        (iv) Soil auger

        It is used for:

        (i)  Soil sampling that is done during soil analysis and testing.

        (ii)  Digging holes for fixing fence posts.

        Maintenance practices

        •   Clean after use. 

        •   Paint to prevent rusting. 

        •   Sharpen the cutting edges. 

        •   Replace any damaged handles. 

        (v) Knapsack sprayer        

        It is used for applying agrochemicals such as foliar fertilisers, herbicides and pesticides to crops efficiently, economically and safely.

        Maintenance practices

        • Wash thoroughly after use and keep in a safe place.

        • Oil or grease the moving parts.

         • Remove dirt, soil and small stones from the sieve regularly. 

        • Check the nozzle regularly to unblock when blocked. 

        (vi) Sprinkler

        It is used for applying water to crops in overhead irrigation.

        Maintenance practices

        •   Unblock the nozzles when blocked.

         •   Clean after use.

         •   Store properly in a dry place after use.

         •   Repair worn out or broken parts. 

        (vii) Hose pipe

        It is used for conveying water from one point to another.

        Maintenance practices

        • Clean after use.

         • Store properly in a tool shed.

        (viii) Garden shear

        It is used for trimming hedges and shrubs in the farm.

        Maintenance practices

        •  Clean after use.

         •  Store properly in a tool cabinet. 

        •  Paint to prevent rusting.

         •  Grease or oil the moving parts to avoid friction.

         •  Sharpen the blades regularly. 

        (ix) Pruning saw

        It is used for pruning perennial crops like coffee, citrus and passion fruits and pollarding trees.

        Maintenance practices    

        • Replace broken handle. 

        • Paint the metallic part to prevent rusting.

         • Set the teeth by use of a saw set so that it is in good condition.

        • Store properly in a tool cabinet. 

        (x) Meter rule

        It is used for measuring out distances such as when planting, to determine spacing or when marking small plots in the farm.

        (xi) Manure fork     

        It is mainly used for moving heavy loads of manure or compost.

        Maintenance practices

        • Clean after use.

         • Handle must be well fixed and replace broken handles.

        (xii) Hayfork

        The tool is used to manually move hay.

        Maintenance practices

        • Clean after use. 

        • Store properly in a tool rack. 

        (xiii) Sickle

        It is a hand-held agricultural tool with a curved blade. It is typically used for harvesting grain crops or cutting succulent forage chiefly for feeding livestock.

        Maintenance practices

        •    Clean sickle after use.

         •     Store properly in a tool rack. 

        •    Handle must always be well fixed onto the blade and broken ones replaced.


        (xiv) Rake maker

        Used for curving various angles on rakes. It can also be used in repairing rakes.

        Maintenance practices

        • Grease or oil regularly to prevent rusting.

         • Store in a dry place, in a tool rack. 

        (xv) Lactodensimeter It is a form of hydrometer for finding out the density of milk. It hence helps in discovering whether milk has been mixed with water or if it has had some of the cream removed.

        Maintenance practices

        It should be cleaned and disinfected after use.

        (xvi) Scythe

        An agricultural implement consisting of a long, curving blade fastened at an angle to a handle, for cutting grass and grain by hand.

        Maintenance practices

        •  The blade must always be well-fastened and sharpened. 

        •  Broken handles must be replaced.

        (xvii) Milk can/ Milk pots

        They are used for:

        • Storing milk.

         • Transporting milk. 

                            

        Maintenance practices

        • Clean and disinfect after use.

         • Store properly in a clean and dry place. 

        (xviii) Milk churn

        This is an instrument used for separating butter from milk by shaking.

        Maintenance practices.

        •  It should be washed immediately after  use.

        •  Store in a clean and dry place.


        (xix) Flail

        This is an agricultural tool used for threshing to separate grains from their husks.

        Maintenance practices

        • Lubrication of the moveable part.

        • Repairing of any broken parts.

        (xx) Strimmer

        It is a tool which uses a flexible monofilament line, instead of a blade, to cut grass (or other plants) that are near objects or on steep or irregular terrain.

        Maintenance practices

        •     The cutting head can be sharpened occassionally when blunt. •    The shaft and handle can be repaired if spoilt.

        Activity 3.4

        1. Go into the school farm and practise using some of the small farm tools you have learnt about. (Also, depending on the season, you can help in the various farm operations using the appropriate tools).

        2. Once you have completed the farm practices, perform the maintenance practices to be done on each of the tools used. (If a tool happens to have been damaged, inform your teacher so that it can be repaired.)

        Activity 3.5: Research activity

        1. Name other farming tools you know that are not in the list above.

        2. State their uses and maintenance practices

        Remember the facts!

        • Farmers use farm tools and equipment mainly for the following reasons:  

        − To increase efficiency and to make farm operations easier.  

        − To minimise injuries to the farm animals. 

         − To enhance production.

         • We must be careful to use only genuine farm tools to avoid injury and damage to crops. • Gardening tools are small farm tools used for carrying out general gardening activities.

        • Farming tools are used for performing various farming activities such as crop production and livestock rearing.

        • For the farm tools to last and serve for long, they must be used appropriately and maintained accordingly. • I should make every effort to learn how to use farm tools and know how to maintain them appropriately.

        Test your competence 3

        1. (a) What are some of the common farm tools you use in your school farm? 

        (b) Classify these tools into farming and gardening tools. 

        (c) What can you do to ensure that each of the farm tools you have named in

        1(a) above last for long and functions as required?

        2. Why should a lactodensimeter and a milk churn be disinfected after use? 3. Farm tools with moving parts must be oiled. Explain why this is necessary. 

        4. Neza keeps some four dairy cows in her backyard. What are some of the tools that you will find in her store room and what will be their use?

        5. A safe distance from other learners should be maintained when handling both sharp and blunt farm tools. Name some of these tools and explain how best they can be handled to avoid injury and damage to the tool.

        6. Which of the following tools cannot be used during nursery preparation?

        A. Digging hoe  

        B.   Garden shear

        C. Manure fork 

        D.   Watering can

        7. Why is it important for tools to be cleaned and kept at a specific designation? 8. Mugwaneza wants to plant maize on a piece of land that he has newly acquired. What tools should he purchase which he shall use from the time of land preparation all the way to the harvesting period? 9. Keza wants to have a small flower garden at the front part of her house. 

        Mention the tools which she will require and explain their uses as well. 

        10. Which one of the listed maintenance practices will not help in improving the efficiency of a rake? 

        A. Sharpening   B.   Fixing handle C.  Replacement  D.   Proper storage



        • We eat a lot of vegetables in our households. They mainly give us vitamins.

          Discussion corner!

          1.  What are your favourite vegetables? Why do you like them?

          2.  Do you know where and how they are grown?

          3.  Look at the picture above. Which vegetables do you know?

          In this unit, you will learn the various classes of vegetables, their importance, how they are grown and how they are preserved. This will prepare you in life to be able to cultivate vegetables and maybe use them as a source of income.

          Key Unit Competency

          After studying this unit, I should be able to cultivate and preserve vegetables.

          Unit Outline

          4.1 Definition and importance of vegetables

          4.2 Classification of vegetable crops

          4.3 Nursery establishment

          4.4 Land preparation and cultivation of vegetables

          4.5 Harvesting indicators of vegetables

          4.6 Preservation of vegetables

          4.1. Definition and importance of vegetables

          Activity 4.1: Research Activity

          1. Find out the various examples of vegetables in your home area.

          2. Using the Internet, find out the importance of vegetables. Note them down and present them in class.

          The facts

          A vegetable is any part of a plant that is consumed by human beings as food in a savoury course or meal. Examples of vegetables include:

          • Cucumber 

          •    Tomatoes  

          •    Onions  

          •    Kales

          • Carrots 

           •    Irish potatoes 

          •    Cabbages 

           •    Lettuce

          • Green bananas 

          •    Cauliflower

           •     Spinach

          The importance of vegetables can be looked at from the following perspectives.

          (a) Improving human health  • There is a reduced risk of susceptibility to many chronic diseases for people who eat vegetables daily. Vegetables provide many nutrients including potassium (which helps to maintain a healthy blood pressure); fiber and folic acid (help the body to form healthy red blood cells).  

          • Dietary fibers from vegetables help reduce blood cholesterol levels and it also lowers the risk of heart diseases.

           • Consuming a diet rich in vegetables may reduce risk of stroke, cancer, heart attack and diabetes.

          (b) A source of income - Large-scale growing of vegetables can earn the farmer money to sustain his/her family.

          (c) There is also improvement of soil through crop rotation. They also provide fodder to domestic animals.

          (d) Vegetable farming is a source of both direct and indirect employment.

          Cultivation of vegetable crops involves intensive operations; starting from sowing to marketing. It provides more and regular employment opportunities especially in rural areas.

          (e) Vegetables also have an industrial importance. Due to their highly perishable nature, vegetables demand comprehensive planning for movement, storage, processing and distribution of vegetable products. Success in the vegetable industry as a commercial proposition largely depends on allied enterprises like storage, processing, marketing, maintenance and service industries, so encourage vegetable farming.

          (f) Vegetables are a source of medicine. In this regard, many of the vegetable crops possess high medicinal value for curing certain diseases.

          Self-evaluation Test 4.1

          1. How are vegetables important to our health?

          2. Name vegetables in your community that are used as medicine.

          4.2 Classification of vegetable crops

          Activity 4.2

          Classify the vegetables you listed in Activity 4.1. Use any applicable criteria you know.

          The facts

          Discussed below are some of the criteria that can be used to classify vegetables.

          (a) Based on edible parts

          From roots to leaves to stems to fruits, different parts of various vegetable plants are consumed. On that basis vegetables can be classified. Table 4.1 gives examples of vegetables classified according to their edible parts.

          Discussion corner!

          1. Which of these vegetables do you know? Which ones do you use in your community?

          2. Find out the importance of each vegetable. Write a report and present to class.

          (b) Based on botanical names

          This method of classification is based on botanical relationships of crops. In Biology, you learnt about the various ranks of classification.

          Discussion corner!

          1. Find out about the various ranks of classification.

          2. Which is the largest and which is the smallest rank?

          3. Which characteristics are used to put organisms in those groups?

          4. Write a report and present in class.

          I have discovered that...

          The various ranks of classification are: • Kingdom 

          • Division or phylum

          • Class 

          • Order

          • Family 

          • Genus

          • Species Kingdom is the largest group while species is the smallest. When classifying vegetables based on botanical names, the class order or family name of the plant is used.

          The facts

          Table 4.2 summarises the various categories of vegetables based on their botanical names.

          (c) Based on hardiness

          Vegetables can be grouped as either hardy or tender on the basis of tolerance to frost; low temperatures etc. The following table shows some examples of vegetables classified according to their hardiness.

          Self-evaluation Test 4.2

          1. Come up with another way in which you think vegetables can be classified.

          2. Why do you think it is important to classify vegetables in this way?

          4.3 Nursery establishment

          Activity 4.3: Research Activity

          1. Find out the meaning of the word nursery in relation to agriculture.

          2. What is the importance of a nursery?

          3. How can we establish a nursery?

          I have discovered that…

          In Agriculture, a nursery is a place where plants are raised with special care until they are ready or mature enough for transplantation into the field (seedbed).

          The facts

          Every farmer who grows seedlings should aim at producing healthy uniform plants that will be able to establish in the field quickly. A wide range of vegetable crops are delicate at a young age. They are therefore raised in nurseries. Examples include cabbages, onions, tomatoes, eggplant, lettuce, celery, broccoli and cauliflower.

          Types of nurseries There are two main types of nurseries:

          • Temporary nurseries – In such nurseries, seedlings are planted for a while after which they are removed and relocated to the bigger field.

          • Permanent nurseries – Here, plants normally grow for all their lives.

          Activity 4.4

          1. Go for a field visit to an established farm and observe the nurseries.  Are they temporary or permanent? 2. Enquire from the farmer some of the factors that led him or her to choose that particular place as a nursery site.

          Selection criteria for a nursery site The site selected as nursery site should:

          • Be levelled and protected from wind. 

          • Be reasonably well-drained to avoid problems that come from waterlogging. 

          • Be free of stones. 

          • Have a nearby reliable source of water.

           • Be fertile.

          The facts

          The following are the major criteria used in the selection of a nursery site.

          4.3 Nursery establishment Activity

          4.3: Research Activity

          1. Find out the meaning of the word nursery in relation to agriculture.

          2. What is the importance of a nursery?

          3. How can we establish a nursery?


          Discussion corner!


          a) Soil type – The site must have good soil that supports the growth of the seedlings. The soil must have enough organic matter and it should respond well to fertiliser and manure.

          b) Climate - Weather conditions are very crucial in nursery establishment. This should be considered with regard to the crops that are to be grown in the nursery.

          c) Water - The availability of water is an important factor to consider in the nurturing of seedlings. The total amount of water a seedling receives will affect its cropping and quality. Irrigation is necessary in the dry season and during drought.

          d) Planting material - It is important to plant varieties suitable for your particular area. It is also important to have healthy planting material. The success of the nursery depends on this.

          e) Market - For commercial purposes, it is very important to have access to the market. A farmer should be able to satisfy the demands of the market.

          Activity 4.5

          Go into your school farm and choose a suitable site to establish a nursery. Consider all the factors you have learnt above.

          Self-evaluation Test 4.3

          Why is it necessary for some plants to be grown in nurseries first before being taken to the main field?

          Nursery preparation for vegetables Nursery preparation refers to the process of making the soil suitable for sowing. The soil should be fine, moist and firm to allow effective germination and be an excellent medium for seedling growth.

          Discussion corner!

          In groups, find out:

          1. The conditions of a good nursery.

          2. What you need to do to prepare a nursery.

          3. How to prepare a good nursery. Write a report and do a presentation to the rest of the class.

          I have discovered that...

          Nursery preparation is necessary to facilitate proper germination and seedlings growth.

          Prior to seeding, the nursery should be levelled and worked on to obtain a fine textured soil free of clods and debris.
          Enough of well decomposed farm yard manure should be mixed thoroughly in the soil. Remember, after a proper nursery preparation: 

           • There must be no weeds in the nursery.   

          • Insects and pests must be exposed to natural hazards and predators.  

          • Proper support for the growing seedlings must be available.

            • The applied fertiliser must offer balanced nutrients to the seedlings.  

          • An optimum supply of soil moisture must be available to seedlings.  

          • Good soil aeration must be facilitated. 

          The facts

          Operations involved in nursery preparation

          1. Ploughing (digging)  This turns the soil from lower layers to the surface exposing the insects in the soil to predators and natural hazards.  This also exposes the weed seeds to the birds and insects. Simultaneously, it mixes the soils of different layers and ensures that the nutrients are well distributed in the soil.

          2. Clod crushing  Clod crushing is required to break the soil particles into finer grains which can facilitate well mixed nutrients, well aerated soil mass and good water holding capacity. Fine soil particles allow the seeds and roots of the seedlings to get good contact with the soil particles.

          3. Manure and fertiliser application  Application of manures and fertilisers replenishes nutrients that are removed during previous growing season, erosion and leaching.

          4. Irrigation is necessary firstly to facilitate the germination of unwanted seeds so that they can be removed during land preparation. Secondly irrigation facilitates other field preparation operations like ploughing or digging which otherwise is difficult in hard, dried soils.

          5. Bed preparation  Bed preparation ensures ease of carrying out cultivation operations like sowing and transplanting, and later in the intercultural operations. The width of a bed should be between 100 - 120 cm and the length should be between 1.5- 15 m. This width facilitates weeding and watering without trampling the bed. The bed should be kept raised at about 15 cm so as to provide proper drainage of excess water.

          Activity 4.6

          Go back to the piece of land you had chosen in Activity 4.5 and now prepare a nursery in your school field. Consider all the factors you have learnt above.

          Sowing methods Sowing methods refer to the means through which farmers plant seeds.

          Discussion corner!

          Discuss the various methods you can use to sow seeds assuming you are a farmer. Which is better? Why?

          The facts

          The common practice is to broadcast seeds in the nursery bed. The other method is line sowing. Line sowing is preferred because it allows checking to ensure proper germination. It also facilitates weeding, hoeing and plant protection operations. Follow these steps when sowing seeds in a nursery.

          1. Preparation of seebed. This involves digging, harowing and mixing manure with soil followed by leveling.

          2. Digging out rows in rediness for sowing.

          3. Planting the seeds. This involves dropping the seeds in the rows then covering  them with soil.

          4. Mulching to protect the seeds from being displaced by rain water.

          5. Watering the seeds.

          6. Constructing a shade to protect seedlings from direct sunlight and rain drops.

          The rows are usually about 5 cm apart. Small seeds are sown mixed with a little sand and are then covered with soil. The soil covering should be lighter in heavy soils. A general rule in this method is to sow seeds 2-3 times their own thickness deep. If seeds are sown too deep, nutrient reserves will be exhausted before the plant emerges; or the emerging plants will be weak, or they will be liable to death. If sown too shallow, then the seeds are likely to be eaten by birds or washed away by running water. Spacing allows for seed losses. However, if one thinks that the seed losses may be higher than normal, then a test for seed viability beforehand becomes necessary.

          How to construct a nursery bed shade

          After sowing the seeds, the nursery bed should be thoroughly watered and a shade erected over it. The following materials are required to make a seed bed shade:

          • Y –shaped sticks about 100 cm long

          • 4-6m long slender sticks.

          • Twigs and leaves of plants.

          Procedure

          1. Dig 4 holes at the corners of the nursery bed. You can add two more holes for support.

          2. Put the Y -shaped sticks into the dug holes.        
          3. Then place the long slender sticks on the Y shaped sticks.

          4. Finally place the twigs and leaves over the slender sticks as shown in Fig 4.4. These will provide the shade. The shade made should be between 75 cm and 90 cm above the bed

          A week before transplanting, the seedlings can be exposed to full sunshine and moisture stress. This ensures that the seedlings are sufficiently hardened for field settings.

          Activity 4.7

          1.Now sow seeds in your prepared nursery bed then prepare a shade as explained above.

          2. Monitor your seedlings frequently to ensure normal growth.

          Self-evaluation Test 4.4

          What advice would you give to a farmer who does not pay attention to the number of seeds he or she puts in each hole when planting?

          Nursery activities Activity 4.8: Research Activity

          1. Find out with your friend the various activities that should be done in a nursery.

          What is the significance of each activity?

          2. Assuming that the activity was not done, what will happen? Why?

          3. Write a report and do a presentation to the rest of the class.

          The facts

          The main nursery practices include:   

          • Harrowing – This is turning of soil using a hoe to improve aeration.

          • Earthing up – Piling up soil to form raised ground. This prevents the seedlings from being swept away by running water.

          • Sowing – Planting seeds in the seedbed for them to germinate into seedlings.

          • Watering or irrigation – Supplying water to young seedlings so as to prevent them from drying up.

          • Mulching – This is putting grass  or other plant materials between lines of growing seedlings to prevent loss of soil moisture.

          • Thinning – This is removing excess seedlings to allow fewer to grow healthy.

          • Weed control – Removing weeds as they grow. This prevents them from interfering with growth of seedlings.

          • Pest and disease control – This is aimed at removing all insects that may destroy the seedlings and protecting them from diseases.

          • Hardening off – This is an operation carried out to acclamatise seedlings to normal growing conditions before transplanting.

          • Shading – This is putting up a shade on the nursery to prevent adverse conditions from influencing the seedlings. At this stage, seedlings are very delicate hence need special care. Once the seedlings are grown and have been hardened off, they can be transferred to the main field. This is called transplanting.

          Fertiliser application on vegetables

          Proper application of fertiliser on a vegetable garden is an important aspect towards successful vegetable growing. The amount of fertiliser applied generally depends on the type of soil and particular crops being grown. Soil fertility requirements differ between growing seasons and among different soil types. The requirements in fertiliser for root vegetables, like carrots, is not the same as that of vegetables in the cabbage family, for example. With regards to soils, those that are rich in organic matter (mostly dark in colour) may not require much fertiliser. Organic matter improves the soil in many ways. It also helps to release various minerals and nutrients that plants require. The two main categories of fertiliser that are mostly applied are organic fertilisers, an example being the compost manure, and chemical fertilisers.

          Chemical fertilisers are mainly of four types:        

          (i) Nitrogenous fertilisers: Examples are ammonium sulphate (NH4)2SO4, calcium cyanide Ca(CN)2, Urea (NH2CONH2) etc.

          (ii) Phosphatic fertilisers: Examples are (triple superphosphate) Ca.(H2PO4)2. H2O, Diammonium phosphate (DAP), phosphatic slag, etc.

          (iii) Potash fertilisers: Examples are potassium nitrate (KNO3) potassium sulphate (K2SO4), etc.

          (iv) Mixed fertilisers: These are made by mixing two or more fertilisers in suitable proportions. An example is NPK (contains nitrogen, phosphorus and potassium in the ratios 17:17:17 for nitrogen, phosphorus and potassium respectively).

          4.4 Land preparation and cultivation of vegetables

          Before transplanting vegetable seedlings, there is need to prepare the field where the vegetables will grow.
          Discussion corner!

          In your groups, discuss about what you need to do before transplanting vegatable seedlings. Why are these activities necessary? Prepare a report and present to the rest of the class.

          The facts

          a) Land preparation This involves four processes

          i) Land clearing – This involves removing obstacles such as trees or other structures before cultivation. It can be done by clearing forests or burning. Chemical methods can also be used.

          ii) First ploughing – This is the initial tilling of the land. It involves breaking the ground using either a hoe, forked hoe or ox ploughs. In mechanised farms, tractor-drawn ploughs are used.

          This opens up the ground, improves aeration and water penetration.

          iii) Second ploughing – This is meant to further break huge boulders of soil into finer particles.T his way, seedlings can grow without difficulties. It is also known as harrowing. It can be done more than once depending on the nature of the soil where the farm is. Harrowing creates suitable tilth that is ready to receive seeds or seedlings.

          iv) Leveling – This is the practice of dragging soil using a leveling board or rake to ensure that the soil is level. This practice helps to improve the chances of survival of the transplanted seedlings. It also ensures that when irrigation is done, there is uniform supply of water and that the roots of growing seedlings penetrate the soil without difficulties.

          b) Planting

          The method of planting chosen depends on the type of vegetables and the field. The two common methods are:

          i) Direct planting –This is where seeds are sown directly on the prepared field. This method may not be appropriate in vegetable farming.

          ii) Indirect planting – This method involves sowing seeds in a nursery then tranplanting them onto the main field. It is the most common practice in vegetable farming.

          c) Maintenance activities of vegetables in the field

          Activity 4.9: Research Activity

          Find out the field practices that should be done in a vegetable farm. Why are those practices important? Write a report and do a presentation to the rest of the class

          The facts

          Some maintenance practices to carry out in a vegetable farm are: • Transplanting • Weeding • Gapping • Watering/irrigation • Pests and diseases control

          a)  Transplanting

          Most vegetables grow better when transplanted. Examples are cabbages, tomatoes and chili. Others do better when directly sown into the fields. These are mainly root crops. There are other vegetables which can either be directly sown or transplanted depending on circumstances.

          Rules for transplanting

          • Transplanting should be done as soon as seedlings are about 4 to 8 weeks old, 10 to 15 cm tall and have formed about 3 to 4 true leaves. • The nursery bed should be watered 24 hours before uprooting the seedlings for transplanting so that they may not suffer from desiccation and minimise root damage.

          • The seedlings should be dug up not pulled out. 

          • When the seedlings are uprooted they experience transplanting shock. Therefore, it is essential to water plants immediately after transplanting and until the plants have recovered.

          • Always transplant under cool conditions so that plants may establish themselves in the cool weather, especially in the night. This also helps to ensure that plants recover from the shock of transplanting before sunrise.

          • Avoid seedlings which have grown too tall. Such seedlings become weak and they may start flowering very early.

          • During transplanting, care should be taken to protect seedlings against wilting. This can be done by frequently sprinkling water on them and covering the roots with moist soil or leaves.

          • Setting the seedlings to a depth of first true leaves when transplanting is known to result in early fruiting and larger fruit size in some crops. 

          Activity 4.10

          1. Prepare the now grown seedlings from your nursery in Activity 4.7 for transplanting. Then carefully transplant the seedlings onto the larger farming field. 2. Keep watching and taking care of the plants until maturity. 

          Self-evaluation Test 4.5

          1. Explain transplanting shock and how it relates with time of transplanting.

          2. Why is it a bad sign when plants start flowering too early?

          b) Irrigation or watering Irrigation refers to artificial application of water.

          Irrigation is done to supplement the available soil water. Water is very essential to plants since it helps to keep the plant body cool and it also facilitates nutrients uptake by the roots of plants. Vegetables are normally between 80 to 95 percent water. Therefore, they require plenty of water during their growing period. General rules for irrigation

          • Always water before water stress symptoms occur.

           •  Water when the atmosphere is cool. 

           • Apply water on soil surface and not on to the plants. This helps to reduce risk of diseases such as blight. 

          • The amount of water to be applied at a given time will depend on the soil moisture content and the water-holding capacity of the soil.

          Self-evaluation Test 4.6

          1. How can one determine the moisture content and water-holding capacity of a given soil?

          2. How will the farmer apply this information during irrigation?

          c)   Weeding 

          Weeds reduce yield and quality of vegetables through direct competition for light, water and nutrients. They also interfere with harvesting operations. Weeds also harbour pests and diseases which can infect or infest the vegetables. Weed competition is very critical and major emphasis of control should be done in the early stages of plant growth. Incorporation of several of the following management practices into vegetable production increases the effectiveness of controlling weeds.

           • Crop competition  • Crop rotation  • Mulching  • Mechanical control  • Use of herbicides 

          b) Hoeing and harrowing 

          Hoeing is the opening of soil in standing crops with the help of a hoe or a pointed stick. Hoeing facilitates breaking of the soil crust (in some soils), aeration of the soil, movement of water in the soil mass and bringing the needed nutrients closer to the roots of the crops. However, hoeing should not be too deep thereby injuring the roots of the crop.

          e) Earthing up - Piling up of the soil on the standing crop is called earthing up. This operation is required for tuber and root crops. It facilitates the growth and development of roots and tuber crops.

          f) Top dressing - Addition or application of fertilisers in the standing crop is termed as top dressing. Top dressing is done to provide nutrients when needed most. It helps to avoid the loss of nutrients through leaching.

          g) Thinning plants - This is eliminating excess plants to let few remain. This reduces crowding and ensures that the crops grow healthy.

          h) Gapping - This refers to replacing seedlings that dried up after transplanting. The seedlings may have dried because of harsh environmental conditions or pests and diseases. Gapping should be done after it has rained.

          i) Mulching-This is covering of the soil with organic matter like grasses and crop residues or with artificial materials like plastic sheet.

          Mulching helps:  

          • To prevent loss of soil water and moisture.  

          • To raise soil temperature.  

          • To reduce growth of weeds.  

          • In adding organic matter, if the mulching material is biodegradable. 

           • To reduce leaching of soil nutrients. All these help to improve soil fertility.

          j) Pest and disease control

          All vegetables will be attacked by some pests and diseases at some stage. The pests that affect vegetable crops can be put into various groups.

          Activity 4.11: Research Activity

          Find out which pests and diseases attack vegetables. How can they be controlled? Write a report and do a presentation to the rest of the class.

          The facts

          Examples of vegetables pests are:

          • Soil insects-Examples are cut worms, white grubs, red ants, wire worms, etc.

           • Stem and foliage feeders-Examples are caterpillars, loopers, diamond back moth, beetles, etc. • Mites and sucking pests-Examples are aphids, whiteflies, plant hoppers, thrips, bugs, etc. • Insects that consume seeds, pods and fruits-Examples are pod borers, fruit borers and fruit flies, etc. Similarly, the diseases that attack vegetables can be grouped as follows: 

          • Root diseases - examples include club roots, damping off, root rot, wilts, etc. 

          • Foliage diseases - examples are blights, rusts, leaf spots, etc. 

           Fruit diseases - examples include fruit rots, anthracnose, fruit blight, etc.

           • Vascular diseases such as wilts. These diseases could be caused by either fungi, bacteria, viruses or nematodes. Often, unfavourable conditions can also cause diseases. Control measures for pests and diseases Any practices which produce strong and healthy seedlings will reduce the risk of pest and disease attack.

          • Maintain high soil fertility and use adequate manures to maintain good soil structure. These will provide soil aeration and a good supply of micronutrients.

          • Use only healthy seeds and seedlings of the desired variety.

          • Varieties with resistance to pests or disease should be emphasised.

          • Crop rotation should be done to prevent build up of soil-borne pests. This also ensures efficient use of nutrients.

          • Practise good crop hygiene. Remove crop debris and weeds that may act as alternative hosts for pests and diseases. Destroy diseased plants, collect insect infested fallen fruits and bury them.

          • Monitor your crops regularly for early detection of problems. Small numbers of pests especially egg masses and larvae can be destroyed by hand.

          • Finally, most crop pests and diseases are controlled through spraying using appropriate chemicals.

          Activity 4.12 

          1. Having learnt the various maintenance practices, carry out the necessary vegetable maintenance activities on your seedlings.

          2. Look out for any pest or disease attacks. Early prevention is better than cure. 3. Once the signs of maturity have been observed, harvesting can be done.

          Self-evaluation Test 4.7

          1. From the aforementioned nursery maintenance practices, which ones help to discourage pests and diseases and how ?

          2. You have been invited to speak to farmers about the advantages of using healthy seeds and seedlings. Highlight the main points of your speech.

          Discussion corner!
          3. Come up with a duty roster to ensure that each member of your class has a specific role to play every day on your nursery project.

          4.5 Harvesting indicators of vegetables

          Discussion corner!
          1. Work with your friends in a group.

          2. Find out what factors to look out for in order to know that vegetables are mature to harvest.

          3. Choose a group leader to take notes.

          4. The group leader should do a presentation to the rest of the class on behalf of the group.

          The facts

          When vegetables are ready for harvesting, there are a number of things to look out for to know the right time to harvest. The three main ones are: days of maturity, size and colour.

          (a) Days of maturity There may be no clear difference between the terms ‘ripe’ and ‘mature’. Produce that is ripe is mature and ripe produce is ready for sale and use. Produce that is mature may or may not be ripe but will ripen if the right conditions are provided. The best example is the mature green tomato. These tomatoes are harvested when they are green but after some time, when under certain conditions, they eventually turn red and soften, such tomatoes are said to be ripe.

          (b) Colour Many vegetables turn colour as they mature; tomatoes and peppers are examples. These colours may vary from one vegetable to another. Also vegetables ready for picking commonly have a shiny, healthy look. If the skin of the crop is dull, the peak time for harvest may have passed, etc.

          (c) Size Most vegetables are ready for harvest when they reach a useable size; depending on the type of vegetable.

          The table below summarises the various characteristics considered when harvesting various vegetables.

          Other factors, which are external also have an impact on the quality of the vegetables. Among them are the time of the day that is most suitable for harvesting. For this case, it is mostly recommended that harvesting of vegetables be done during the coolest time of the day, which is usually early morning or late in the evening. The shelf-life of produce is closely tied to its respiration rate. The higher the respiration rate, the shorter the shelf-life of the product. The respiration rate is also directly related to the air and produce temperature. At high temperatures, the respiration rate is high, so the shelf life of produce is reduced. Keeping the produce’s temperature low increases shelf-life. Optimum storage temperature and harvest temperature differences should be kept to a minimum. By harvesting during the cool times of the day, this will be accomplished; hence shelf-life will be prolonged.

          Activity 4.13

          Observe your vegetables and see whether they have matured yet or not. Consider the harvesting indicators you have learned in class.

          4.6 Preservation of vegetables

          Activity 4.14: Research Activity

          Find out how people preserve vegetables in your community. How about modern methods of vegetable preservation? Comparing the two, which ones are more effective? Why? Write a report and present it to class.

          The facts

          Vegetables should be prepared for preservation as soon as they are harvested. This should be within 4 to 48 hours after time of harvesting. The likelihood of spoilage (any change in food that causes it to lose its desired quality, eventually becoming inedible) increases rapidly as more time passes by. Some of the methods of preserving vegetables are discussed below.

          1. Blanching or pre-cooking 

          This is done by immersing vegetables in water at a temperature of 90-95°C. Exposing them to steam is also recommended. The result is that fruits and vegetables become somewhat soft and the enzymes are inactivated. Blanching is done before a product is dried in order to prevent unwanted colour, odour changes and an excessive loss of vitamins.

          Note: Fruits that do not change colour generally do not need to be blanched. Onions and leek are not at all suited for blanching. 

          The relevant examples of vegatables that require blanching are:

          • Peas and beans before canning in order to inactivate enzymes

          • Irish potatoes to prevent browning when making French fries.

           • Green beans before cold storage. 

          • Cabbages.

           • Carrots. 

          • Pea pods. 

          2. Preserving by heating

          One of the most common and effective ways of preserving fruits and vegetables is to prepare them and place them in air-tight containers, which are then heated. The high temperatures ensure that microorganisms are killed and the enzymes are inactivated. Some examples of food preserved by heating include:

          • Canned cabbages. 

          • Canned green beans. 

          • Canned bean pods. 

          • Canned green peas. 

          • Canned carrots.

           • Canned pea pods.

          Advantages

          • Most microorganisms are destroyed so there is a low chance of spoilage. 

          • After being sterilised and stored, the food can be kept for longer and more safely.

          Disadvantages

          • Heating requires the following which makes it expensive:  – Heat-resistant storage containers such as cans or glass jars (which   can be difficult to get).

          The latter are preferred because they canbe   reused.   – Cooking utensils, such as a steamer.   – Fuel

          • The costs above will have to be represented in the final cost of the product.

          • This method is labour intensive.

          • It requires access to abundant clean water.

          • Heated fruits and vegetables have a lower nutritional value as some nutrients are destroyed by heat for example vitamins. 

          3. Pasteurisation and sterilization

          This is done to prepare food items for storage in glasses, bottles or tins. Glass bottles and jars can be used for sterilisation and pasteurization. They are normally reusable. However, they are also breakable and when transparent, they do not protect food from the negative effects of light.

          This problem can be solved  by storing the filled bottles and jars in a dark place.Glass bottles, those previously used for soft drinks or beer for example, are well suited for heating and storing fruit pulp, puree or juice.

          They have to be sealed with a metal screw cap. Their volume can vary from 0.2 to even 2 litres.

          • Sterilisation refers to heating above 100°C. It can be done in a pressure cooker or an autoclave (large pressure cooker).

          • Pasteurisation is a mild heating treatment at temperatures of up to 100°C (which is the boiling point of water at elevations of up to 300 m above sea level). This method causes only a slight decrease in taste and nutritional value. The enzymes are inactivated and most, but not all, bacteria are killed. Pasteurised products therefore spoil faster than sterilised products. To prevent the surviving spore-producing microorganisms from multiplying, the produce should be stored in temperatures below 20°C.

          4. Drying – This is one of the oldest preservation methods. The moisture level of agricultural products is decreased to 10-15% so that the microorganisms present cannot thrive and the enzymes become inactive. Further dehydration is usually not desired, because the products then often become brittle. To ensure that the products do not spoil after being dried, they have to be stored in a moisture-free environment. The final quality of the dried product is determined by many factors. They can however be divided into four groups: 

          a) Quality of the product to be dried. 

          b) The preparation of the product. 

          c) The drying method used. 

          d) The packing and storage conditions.

          5. Use of preservatives

          Fruits are sometimes treated with smoke from burning sulphur or are dipped in a sulphite or thiosulphate-salt solution to prevent browning. Taste and vitamin C content are also better preserved with these treatments. The residual sulphite in the product can, however, be dangerous in high concentrations and can also affect the taste.

          6. Pickling – This is done by dipping the food in vinegar. This method of preserving vegetables can be done with cabbages, beets, onions, cucumber and fruits such as lemons and olives. To obtain a product that can be stored, the food first has to be salted and heated before being put into vinegar. We can remove water (drying), increase the acidity, or first heat the product (to kill the bacteria) and then store them in air-tight containers to prevent oxygen from entering (bottling or canning).

          7. Freezing – This is another age-old method of preservation. Vegetables are kept at very low temperatures (-40°C) after having been collected and washed properly. However, frozen vegetables do not have the same properties as fresh ones because many vitamins are lost in the process.

          8. Fourth generation vegetables

          These are vegetables preserved in vaccum plastic bags or trays ready to be consumed directly. Before this is done, vegetables are very well cleaned and chopped. The oxygen is removed and the product is packed in nitrogen gas. This prevents the survival of microorganisms. These products are normally fresh and can be eaten as salads; oil and salt may be added. There are a wide variety of vegetables in the market stored using this method. They include lettuce, endives, carrots and celeries.

          9. Fermentation of vegetables

          During fermentation of raw vegetables, lactic acid bacteria develop, transforming the natural sugars present and the added sugar into an acid. In general, a low salt concentration of 3-5% is used to prevent the growth of spoilage bacteria; while lactic acid bacteria are developing. The characteristic flavour and texture of fermented vegetables is produced by the action of lactic acid bacteria. Vegetables must be kept submerged in the liquid to prevent contact with air, which can cause decomposition. Due to action of yeasts and moulds during the fermentation process (2 to 3 weeks), the salt becomes diluted due to water drained from the vegetables, therefore salt must be frequently added to maintain the concentration at 3-5%.

          10. Vaccum packaging

          Vacuum packaging extends the shelf-life of vegetables for long periods. This technique relies on the withdrawal of air from the package with a suctioning machine. Removal of air retards the development of enzymatic reactions and bacterial spoilage. Vacuum packaging and gas flushing establish the modified atmosphere quickly and increase the shelf-life and quality of processed products. For example, browning of cut lettuce occurs before a beneficial atmosphere can be established by the product’s respiration. In addition to vacuum packing, the specifications of handling must be taken into account, especially the time delays and temperature fluctuations.

          11. Canning (Tinning)

          This is a food preservation method in which processed food is sealed in airtight containers. It is a reliable method as it increases the shelf-life of food to up to five years. The canning process involves placing foods in jars or similar containers and heating them to a temperature that destroys micro-organisms that cause food to spoil. Heating drives out air out of the jar and as it cools, a vacuum seal is formed. The vacuum seal prevents air from getting back into the product hence preventing the entry of microorganisms.

          Activity 4.15

          Perform a vegetable preservation experiment using any method that you know. (This should be done in the Biology laboratory.) Use the vegetables that you will have harvested from your school farm.

          Self-evaluation Test 4.8

          Classify the various vegetables with their most appropriate methods of preservation.
          Remember the facts!

          • A vegetable is any part of a plant that is consumed by human beings as food in a savoury course or meal. • The following are some benefits of vegetables: 

          − Improving human health  

          − A source of income  

          − Improving soil fertility when incorporated in crop rotation programmes

           − A source of employment 

           − Industrial importance 

           − Medicinal value 

          • The three major ways of classifying vegetables are based on: 

           − Edible parts 

           − Botanical classifications  

          − Hardiness

           • A nursery from the agricultural point of view is a place where plants are raised with special care until they are ready for transplanting into the field.

          • The following are the major types of nurseries: 

           − Temporary nurseries 

           − Permanent nurseries 

          • Some of the major criteria used in selecting a nursery site are:  

          − Soil type  

          − Climate 

           − Water availability  

          − Planting material  

          − Availability of market 

          • Nursery preparation refers to the process of making the soil suitable for sowing and transplanting of seedlings.'

          • Some of the operations involved in nursery preparation include: 

           − Irrigation 

           − Hardening off

           − Pest and disease control

           − Earthing up 

          − Mulching 

          − Thinning 

          − Shading 

          − Harrowing

           − Manure and fertiliser application 

          • Sowing methods are the modes by which farmers plant seeds. This can be direct or indirect through transplanting.

          • The two main nursery activities are: 

           − Transplanting 

           − Irrigation or watering 

          • Maintenance activities of vegetables are those activities that help in ensuring 

          that the seedlings in the field grow healthy and strong. They include:  

          − Weeding 

           − Hoeing and harrowing 

           − Earthing up 

           − Top dressing 

           − Thinning 

           − Gapping 

          − Mulching 

          • Vegetables are also attacked by some pests and diseases. They should be controlled before they cause damage. • Harvesting indicators for vegetables include days of maturity, size and colour. 

          • Vegetables should be prepared for preservation as soon as they are harvested. Examples of preservation methods are:  

          − Blanching or pre-cooking  

          − Preserving by heating  

          − Pasteurisation or sterilisation 

           − Drying 

           − Use of preservatives  

          − Prickling in vinegar or acetic acid  

          − Freezing  

          − Fourth generation vegetables 

           − Vacuum packaging.
          Test your competence 4

          1. Why is classifying vegetables important?

          2. Why is it important for some vegetables to be planted in nurseries first before being taken to the field?

          3. Name some farm tools that can be used in the operations performed during nursery preparation.

          4. Why is weeding an important operation in nursery preparation?

          5. What are some of the irrigation or watering methods you know that can help save on water? 6. Of the listed, what is not important when considering a site for a nursery? 

          A. Soil type 

          B. Type of plant

          C. Topography

          D. Proximity to water

          7. Transplanting is a very delicate process. Explain. 8. Mutoni wants to minimise pest and disease attack on the seedlings in her nursery. What would you advise her to do?

          9. The nutritive value of vegetables is important. How can we ensure that the nutrients in vegetables are not interfered with?

          10. Ntwali wants to preserve vegetables to be sold in the next two weeks. Which preservation methods would be most appropriate for storing vegetables for this long? 11. Mugwaneza bought tinned vegetables only for him to reach home and find them spoilt.  a) What was Mugwaneza’s mistake and what should she have done at the shop? 

          b) Describe the method that may have been used to preserve the tinned vegetables.

          12. Which of the following is not done during nursery bed preparation?

          A. Top dressing

          B. Ploughing

          C. Fertiliser application

          D. Clod crushing



          • TOPIC AREA 3: ANIMAL PRODUCTION

            Unit 5: Animals

            In Rwanda, rearing of non-ruminants such as rabbits has continued to be dominated by smallholder farmers and very few big farmers. This is of great concern because these animals can be a source of income through their products. Their wastes (manures) can also be used as manure in the farms.

            Key Unit Competency

            After studying this unit, I should be able to:

            a) Identify non-ruminant species and breeds.

            b) Successfully conduct rabbit rearing.

            Activity 5.1

            Your teacher will take you for a field visit to a farm that keeps non-ruminants. Observe the various types of non-ruminants present. Identify them (with the help of the farmer) and note down their characteristics.

            Non-ruminants are also called mono-gastric animals. The animals have one stomach and they swallow food once without regurgitation.  Examples of nonruminants are dogs, cats, pigs, rabbits and poultry. Name five other non-ruminants that you know.

            5.2 Non-ruminant species and breeds

            The non-ruminants that you will learn about at this level which are commonly reared in Rwanda are: • Poultry • Pigs • Rabbits

            a) Breeds of poultry

            Activity 5.2: Research Activity

            1. Using the internet search engine and other text books, find out the various breeds of poultry in Rwanda. 2. Your teacher will now show you a video on poultry keeping. Watch the video and note down the characteristics of various breeds of poultry.

            3. Discuss in groups the characteristics of the breeds.

            4. Write down the main points and do a presentation to the rest of the class.

            The facts

            Poultry refers collectively to domesticated birds. They include chicken, ducks, guinea fowls, geese and turkeys among others. However, in this unit, you shall only learn about chicken as a representative of the poultry family.

            Chicken can be kept for meat, eggs or both. The common breeds of chicken reared in Rwanda are:

            (i) Rhode Island Red     

            It is a dual purpose breed meaning it is reared for both meat and eggs. It is the most popular of all dual purpose breeds of chicken.

            • Rhode island red originated from America.

            • The bird lays brown-shelled eggs. 

            • It has good quality carcass.

             • They are mostly docile hence easy to manage. 

            • The bird has a broad deep angular body. 

            • Cocks weigh 4.0 kg while hens weigh 3.5 kg.

            • It also has well  formed breasts that protrude forwards while the back is flat. 

            • Their main disadvantage is their yellow skin which is normally unpopular with consumers.

            (ii) Sussex

            The most common type of Sussex is the Light Sussex. It is a broiler meaning it is kept for meat.

            • Its origin is Great Britain.

            • Cocks weigh 5.0 kg while hens weigh 3.0 kg on  average.

            • They have a high meat conversion rate. 

            • They lay small tinted eggs.

            • They have a large body with good deep and broad shoulders. 

            • The breast is well developed with excellent meat qualities.

            (iii) Derco             

            It is a French hybrid. It shows slow growth when compared with other exotic chicken breeds. It also shows a high potential of crossbreeding with other chicken breeds.

            (iv) Local breeds
            This is the most common breed in Rwanda. It is a multipurpose breed that is very hardy. It lays between 40 and 100 eggs per year and the adult weight is reached in more than 10 months. The breed combines the needed quality of production and resistance to diseases. It adapts very well to the local conditions and is easy to manage.


                  fig.5.5: local breeds

            (b) Breeds of rabbits

            Activity 5.3

            1. Using the internet search engine and text books, find out the various breeds of rabbit.

            2. Your teacher will now show you a video on rabbit rearing. Watch the video and note the characteristics of various breeds of rabbits.

            3. Write down the main points and do a presentation to the rest of the class.

            The facts

            Rabbits are mainly kept for meat and fur or hair. Their skin is also used in making soft upholstery such as seat covers.

            The common breeds of rabbits reared in Rwanda are:

            (i) Angora This is a domestic rabbit bred for its long, soft fur. The Angora breed is one of the oldest of the domestic rabbit breeds. The breed has poor body conformation and its average weight is 2.5 kg.

            (ii) California white

            • It is white with black or dark brown ears, eyes, nose and feet.

            • Adult bucks weigh 5.0 kg while adult does 
              weigh 3.5 kg on average.

            • It is very prolific and is widely used for cross breeding.

            • It is kept for meat. 

            (iii) New Zealand white

            • It is white with pink eyes.   
             
            • Bucks are blocky and compact. They weigh 5.0 kg on average.

            • Does on the other hand weigh 4.5 kg on average.

            • They have a long body and a wide back. 

            • The breed is prolific and fast growing.  

            • The breed is mainly kept for meat.

            (iv) Local breeds of rabbits

            Fig. 5.10: Local breed of rabbits in Rwanda
             

            The local breed of rabbits has the following characteristics:

            • It is black with white patches and pink eyes.

            • They have a short body. 

            • They weigh 2.0kg on average.

            • The breed is not prolific and gives birth to few young ones.

            • The breed is slow-growing but resistant to many rabbit diseases.

            • They are reared mainly for both meat and skins.

            (c) Breeds of pigs

            Pigs are reared for either pork or bacon production. Pork is meat from a young pig weighing 45-50kg and at 4 months. The meat is not salted. Bacon is meat from an old pig weighing 110kg live weight, slaughtered at 7 months. Bacon is salted and is normally obtained from the back and sides of the pig.

            Activity 5.4 1.

            Using the internet search engine and text books, find out the various breeds of pigs.

            2. Your teacher will now show you a video on pig production. Watch the video and note the characteristics of various breeds of pigs.

            3. Write down the main points and do a presentation to the rest of the class.

            The common pig breeds reared in Rwanda are:

            (i) Large white

            Large white originated from York shire, Britain. It is widely reared in many parts of Rwanda. It is mainly kept for pork.

            • It is long, large and white in colour.      

            • It has erect ears. 

            • It has a dished face and a snout.

             • It is the most prolific of all the pig breeds. 

            • It has good mothering ability and it is a high milker.

            • It is susceptible to sun burn. 

            • It matures late. 

            • It is a good converter of feeds into meat. 

            • It is fairly hardy. 

            • It has strong hind legs. 

            • It has a sagging back and a level underneath. 

            (ii) Landrace This breed originated from Denmark. It is kept for bacon production.

            • It is white in colour.

            • It is longer than the large white. 

            • Its ears are long and they droop over the face.

            • It is as prolific as the large white. 

            • It also has good mothering ability. 

            • It requires high level management skills. 

            • It has a sagging back and weak hind   legs.

            • It has a straight snout.

            (iii) Pietrain

            This breed was introduced in Rwanda by Brother Cyrile. Some were imported by the government of Rwanda. Their number in Rwanda is restricted in different parts of the country. Its origin is Belgium.

            • It is medium-sized.           
            • It is white in colour with round black spots and characteristic rings of light pigmentation that have white hair.

            • Their ears are erect.

             • It is renowned for its very high yield of lean meat.

            • It has good mothering abilities. 

            • It matures fast and it is also a good converter of feed into meat.

            (iv) Local or traditional pig breeds

            The traditional pig breed in Rwanda is smallsized, hardy and with low productivity. It also has low exigencies, which fits perfectly in an environment with scarce resources and low level management capacity. Local pigs are of different colours (mainly black or spotted) and are available in various sizes. It is obvious that there has been

            crossbreeding taking place in the past but it is hard to assess how much and whether there are still pure traditional pigs.

            Self-evaluation Test 5.1

            1. What is a non-ruminant animal?

            2. Which non-ruminants are reared in Rwanda?

            3. Draw and label a: 

            a) Hen   

            b)   Rabbit   

            c)   Pig

            4. What are some of the advantages and disadvantages of keeping local or traditional breeds of the above mentioned non-ruminants?

            5.3 A rabbit hutch

            Activity 5.5: Research Activity

            1. What is a hutch?

            2. Go for a field visit to a rabbit farm and observe the available rabbit hutches, the materials they are made of and how the materials are arranged.

            3. Afterwards, research and discuss the standards used and the different operations involved in the construction of a rabbit hutch.

            4. Write a report and do a presentation to the rest of the class.

            The facts

            Rabbits are kept in structures called hutches. Rabbit hutches can be constructed in two ways.

            1. One structure consisting of several hutches. The structure is normally immobile, i.e., cannot be moved. The food is brought to the rabbits while they are in the hutch.

            2. Single hutches. Here, the hutches can be moved from place to place. The rabbits feed on the grass that sticks through the wire part of the floor of the hutch. The following are the necessary materials required in the construction of a hutch: timber, iron sheets, nails and iron wire nets.


            Each hutch should measure 120 cm by 60 cm by 60 cm. A hutch for the doe should have a nesting box besides feed and water troughs. They also have resting and sleeping areas. The floors of the sleeping and nesting boxes should be wooden. The rest of the floor can be made of a wire netting of 1cm mesh or slats spaced 1cm apart. The nesting box should measure 38 cm by 25 cm by 20 cm. In hot areas, the wall should be made of a wire netting. In cool areas, only the front wall is to be covered with a wire net to let in light and allow for ventilation.

            Note: All hutches should be raised 1 m above the ground.

            The example given here is that of one rabbit hutch. Feel free to vary the size according to the number of rabbits you want to rear.

            Step 1: Site selection

            hutches are typically made of exterior grade ply-wood for placement outdoors. Choose a covered location that will protect the hutch from harsh weather and from predators. Remember: It is hard for rabbits to endure high temperatures.

            Step 2: Build the frame

            The first step is to build the outer frame. The dimensions of the frame for one rabbit are as shown besides. Remember, the front part should be taller to allow slanting of the roof. This ensures that rain water fall off easily when it rains. Use a spirit level to check that all the corners are straight and properly aligned.

            Step 3: Fit a floor panel

            To prevent your rabbit from escaping by digging a rabbit hole, fit a floor panel in the rabbit hutch. If you do not mind your rabbit digging into the ground, put a strong wire gauze under the ground (about 20 cm deep). This way, your rabbit will have the freedom to dig, but won’t be able to escape.

            Step 4: Make the sidewalls

            Make the sidewalls of the rabbit hutch by screwing the planks of wood to the frame. You can also nail the wood onto the frame. You can then fix wire gauze to the openings using staple nails.

            Step 5: Fit the interior panel

            The interior panel is intended to serve as a night shelter. Make an opening in the panel that’s big enough to let your rabbit go in and out.The interior panel can also have the nesting boxes. Water and feeding troughs can be placed at the front panel.

            Step 6: Fit the finishing strips

            Finish the outside of the hutch with decorative strips to cover the sharp edges of the gauze. Check that all the corners are straight and properly aligned.

            Step 7: Make the doors

            Make the doors as shown in the drawing. Use two galvanised or stainless steel hinges on both doors. Fit bolts on the upper and lower doors.

            Step 8: Finish the roof
            Make a roof frame from beams of the right size,so the outside of the rabbit hutch covers the frame. Make the roof panel from a piece of 12 or 18 mm shuttering plywood or waterproof plywood.
            Screw the roof panel to the frame with two hinges. Make sure the roof panel overlaps by at least 5 cm all round, and by 10 cm at the front. That prevents water entry, so the inside of the rabbit hutch stays dry.
            Step 9: Make the roof water-proof
            It’s important to make sure that the roof of the rabbit hutch is waterproof, so cover it with self-adhesive bitumenised roofing. You can also use iron sheets or polythene bag to cover the roof as shown.
            Your rabbit hutch is now ready for use but before that, put saw dust and soft grass on the floor. This offers a soft ground for the rabbit to sleep and play.
            Activity 5.6
            Construct a standardised hutch, considering the steps shown above. Work in groups and:
            1. Come up with a plan of action.
            2. Execute the plan.
            3. Look back and discuss the challenges encountered.
            4. Discuss how you would avoid these challenges in future projects.

            Self-evaluation Test 5.2
            1. In which two ways can rabbit hutches be constructed?
            2. Name the materials necessary for the construction of a rabbit hutch.
            3. Why should the roof of a rabbit hutch be slanting?
            4. What can you do to prevent your rabbits from digging rabbit holes?
            5. What is the use of saw dust and soft grass on the floor of a rabbit hutch?

            5.4 Feeding rabbits

            Activity 5.7
            Go for a field trip again to the rabbit farm, or any other appropriate one to find out how rabbits are fed. You should note down the following:
            (a) Appropriate ingredients for a rabbit diet.
            (b) The different possible diets for a rabbit as per its age and body weight.
            (c) The feeding plan for a rabbit for a week.

            The facts
            Rabbits feed on a wide range of foods. These include:
            • Greens such as cabbages, kales, vines and Napier grass.
            • Root tubers such as carrots, cassava and turnips.
            • Concentrates such as dairy meal, dairy cubes and fish meal. These should be fed to pregnant and nursing rabbits. Some salt licks should also be provided.
            • Plenty of water.Young rabbits should start eating solid food at the age of 2½-3 weeks. Feeding should be done in the mornings and evenings, but water should be available all the time.

            Feeding plan for rabbits

            For good rearing, rabbits must have at their disposal enough food and water. One healthy rabbit consumes food that is 50% of its body weight per day but this should not exceed 2kg of feeds. For rabbits with more than 4kg body weight include concentrates of these feeds. This should be put in a rack near the litter. Below is a general feeding plan for rabbits right from birth:
            • From weaning time to one month after weaning: 50 g per day per rabbit.
            • At 2 months after weaning-75g per day for each rabbit.
            • At 3 months after weaning-100g per day for each rabbit.
            • Rabbit at the age of over 3 months-100g per day for each rabbit.
            • Nursing rabbits-300-400g per day, according to the number of young rabbits.
            Activity 5.8
            1. Consider the feeding plan you have learnt about in class and plan the types of rabbits you will want to bring into your rabbit hutch(es).
            2. Organise with your teacher to purchase the food and the rabbits as well. Note: This may take time, therefore plan early.
            Self-evaluation Test 5.3
            1. Young rabbits start feeding on solid foods much later (after 2½-3 weeks). Why is this so?
            2. Name some of the locally available foods that you can feed your rabbits on.
            3. Why do you think feeding should only be done in the mornings and evenings?

            5.5 Rabbit diseases, pests and enemies

            Activity 5.9
            1. Your teacher will show you a video displaying the different rabbit diseases and enemies. From the video, note down the following:
            (a) The names of the various diseases and enemies of rabbits.
            (b) The characteristics (symptoms and signs) of each disease.
            (c) The causes or any predisposing factors of the rabbit diseases and enemies.
            (d) Prevention and curative control methods.
            2. After the video, discuss what you will implement in your rabbit hutch to ensure that your rabbits stay healthy.
            3. Write a report and choose one group member to make a presentation to the rest of the class.

            The facts
            Some of the common diseases and pests that attack rabbits are given in the table that follows.


            Self-evaluation Test 5.4
            1. From the listed pests and diseases, which ones do you think you can control through having good hygienic practices?
            2. What is quarantine?
            3. Which rabbit disease leads to a watery, whitish to yellow nasal discharge?
            4. What causes retarded growth in young rabbits suffering from coccidiosis?

            5.6 Farm sanitation rules for rabbit rearing

            Activity 5.10
            1. Visit a rabbit farm once again and inquire about the sanitation practices they conduct in the rabbit hutches.
            2. Find out why the practices are important.
            3. Write a report and do a presentation to the rest of the class.

            The facts

            To have the highest output from rabbit keeping, proper sanitation measures should be taken in the farm. These help to ensure that the rabbits are growing healthy and strong. This way, their rate of reproduction is high and they have quality meat for sale.
            The following are some of the sanitation practices that can be performed in a rabbit hutch.
            a) Good ventilation: A properly designed ventilation system.
            This is important because it:
            • Removes excess moisture from the hutch.
            • Removes harmful gases from the hutch.
            • Ensures that the temperatures in the hutch are at favourable levels.
            • Ensures proper air circulation.
            • Discourages harbouring of disease-causing organisms.
            b) Lighting - Indoor housing facilities for rabbits should have ample light. Both natural light and artificial light should be available. These should allow for routine inspection of the rabbits.
            c) Shelter from sunlight– Outdoor housing facilities should provide each animal with a section of shade that protects it from direct exposure to the sun. When sunlight is likely to cause overheating or discomfort, sufficient shade should be provided to all rabbits.
            d) Shelter from rain–Rabbits kept outdoors should be provided with access to shelter when it rains.e) Protection from predators–Outdoor housing facilities for rabbits should be fenced or enclosed to minimise the entry of predators.
            f) Provide a good drainage system. A suitable method should be provided so as to rapidly eliminate excess water or any fluids.
            g) Proper waste disposal–There should be regular disposal of animal and food wastes, replacement of beddings, removal of dead animals and debris. This will help to minimise vermin infestation, contamination, odours and disease hazards.
            h) Cleaning of primary enclosures – primary enclosures should be kept reasonably free of excreta, hair, cobwebs and other debris through periodic cleaning. Thorough cleaning should be done regularly.
            i) All watering receptacles should be sanitised-with an aim of preventing algae build up and contamination.
            j) Supplies of feed can be stored in sealed containers-or any other containers that protect the feeds against insect and rodent infestation and/or contamination.

            Self-evaluation Test 5.5
            1. Why is good lighting and ventilation important for rabbits in a rabbit hutch?
            2. Why is it important to regularly dispose of waste from a hutch?
            3. Which diseases and pests can be brought about by poor sanitation in a hutch?
            4. Overfeeding rabbits can be fatal to them. Explain why.

            Project Work

            1. Begin a rabbit keeping project with your friend. Ensure that you observe all the rabbit keeping best practices.
            2. Do the following:
            • Write a plan for the project. This should include what you require and the costs involved and how to get the money for the start up.
            • Execute the plan.

            Remember the facts!
            • Non-ruminants are also called mono-gastric animals. Such animals have one stomach and they swallow food once without regurgitation.
            • The most common non-ruminants reared in Rwanda are poultry, pigs and rabbits.
            • Poultry refers collectively to domesticated birds.
            • Chicken can be kept for meat, eggs or both.
            • The following are common breeds of chicken kept in Rwanda:
            − Rhode Island Red
            − Light sussex
            − Derco
            − Local breeds of chicken
            • Rabbits are mainly kept for meat and fur or hair.
            • The following are some common breeds of rabbits in Rwanda:
            − Angora
            − California white
            − New zealand white
            – Local rabbit breed
            • Pigs are reared for either pork or bacon production.
            • Pork is meat from a young pig weighing 45-50 kg and at 4 months age.
            • Bacon is meat from an old pig weighing 110 kg and at over 7 months of age.
            • Some common pig breeds reared in Rwanda are :
            − Large white
            − Landrace
            − Pietrain
            − Local or traditional pig breeds
            • The structure in which rabbits are kept is called a hutch.
            • The necesarry materials required in the construction of a hutch are timber, iron sheets, nets and iron wire nets.
            • All hutches should be raised 60 cm above the ground.
            • Some of the foods that rabbits feed on are cabbages, kales, vines and nappier grass.
            They also eat roots such as cassava, carrots and turnips. Also, concentrates such as fish meal or dairy meal are good sources of proteins for rabbits.
            • Diseases and pests reduce the growth rate in rabbits and they may sometimes even lead to death. Appropriate measures should be put in place to prevent or control them.
            • To have the highest output from rabbit keeping, farm sanitation needs to be observed.
            • Some of the essential sanitation practices include :
            − Good ventilation
            − Shelter from rain
            − Proper lighting
            − Protection from predators
            − A good drainage system
            − Proper waste disposal
            − Cleaning of primary enclosures
            − All watering receptacles should be sanitised
            − Supplies of feed can be stored in sealed containers.
            • When coming up with a rabbit farming project, you should write a plan, determine the type of rabbits to rear and execute the plan. You should later look back and determine the challenges encountered and come up with ways of addressing them in the next project.

            Test your competence 5

            1. Which ones of the following are not ruminants?
            A. Cows
            B. Goats
            C. Pigs
            D. Sheep

            2. Between ruminants and non-ruminants, which ones would you prefer to rear and why ?
            3. Keza wants to raise pigs for small scale pork production. Which breeds would be most appropriate for her and why ?
            4. Of the three breeds of rabbits discussed, which one would you prefer keeping and why?
            5. Mention some of the sanitation practices you can perform in a hutch to prevent spread of diseases.
            6. Which rabbit breed fits the description below?
            (i) Widely used for crossbreeding.
            (ii) Is white with dark brown ears, eyes, nose and feet.
            (iii) Is mainly kept for meat.
            7. Mention some of the tools that will be used in the construction of a hutch and their uses.
            8. Come up with a weekly feeding plan for 2 weeks old rabbits. (Hint: The foods in the plan must be balanced)
            9. Which is the best method of dealing with sick rabbits in a hutch? Explain.
            10. How can a rabbit farmer ensure that his rabbits are well protected from predators ?
            11. What are some of the important things a rabbit farmer should observe in feeds before giving it to the rabbits?
            12. Ngabo is a prospective rabbit farmer. He is looking for a piece of land that would be most suitable for his venture. Explain some of the factors he should consider before settling on any given piece of land.


            • Up to this point, you have learnt about the various species of livestock and how useful they are to the farmers. In this unit, focus shifts to livestock products and their importance in our lives. Therefore, this unit prepares you to appreciate the various animals and the benefits we derive from them. At the end, you should be able to start a farm and earn a living by selling livestock products.