Science and Elementary Technology

Introduction

Soil is essential for survival of both plants and animals. It provides a surface on which plants grow. It is also a habitat for many animals.

Look at the following pictures.

Describe each picture above.
Predict what you are going to learn.

9.1: Preparation of soil for cultivation

• Preparation of soil involves activities that are carried out on land before seed are planted or seedling are transplanted.
Name all the activities that are done on land before planting seeds.

Activity 9.1: Preparing plots for cultivating in vegetables

Requirements:
• Hoe           • Rake
• Tape measure of strong manila string
What to do:
(i) Your teacher will assign you a piece of land. Use a tape measure to divide the piece of land into small plot.

(ii) Prepare your plot for planting maize seeds. Do this by:
• Clearing the land
• Digging for the first time
• Digging a second time to make the soil fine.
• Levelling the seed bed by removing stones and other wastes.

(iii) Ensure that you break the soil into small particles, remove wastes and bury organic matter deep in the soil.

(iv) 3-4 days after the above activities, add manure or fertiliser to the soil.
Turn the soil over and over to mix it with the fertiliser.
(v) Level your seedbed using a rake.
(vi) Make furrows on your seedbed using a hoe. Your seed bed is now ready for planting seeds.
(vii) What can the vegetation that this man is clearing in the picture alongside be used for?

Land clearing
Land clearing done by cutting or uprooting vegetation on a piece of land.
Name 4 types of vegetation that is cleared.
To clear the land tools like machetes, axes, slashers and saws are used.

                                       Fig. 9.1 (a) and (b): Land clearing.

Ploughing

Ploughing also referred to as primary cultivation of soil. It can be done as shown below

                                              Fig. 9.2 (a) and (b): Primary cultivation.

Ploughing involves digging up the soil and turning it over. It opens up the land, loosening soil particles.
During this cultivation soil is broken into big irregular soil lumps.

Secondary cultivation
Secondary cultivation is done after primary cultivation.
It is done on a dug seed bed before the seeds are planted or seedlings are transplanted. This involves furrowing.

From the picture above, explain how furrowing is done. Can furrowing be done using a hoe?

Levelling
Levelling is done when preparing a seed bed.
What is a seedbed?
Levelling of a seedbed is done using a rake.
Name three materials that are removed from soil during levelling.

9.2: Fertilisation of soil for cultivation

Activity 9.2: Classification of fertilisers

(i) Obtain a little fertiliser that is bought from the shops and bring it to school.
(ii) Obtain drying leaves, sticks and other plants materials and bring them to school.
(iii) Obtain dried cowdung and bring it to school.
(iv) Write down all the similarities and differences between materials
obtained in steps (i), (ii) and (iii).
(v) Classify the materials into two groups based on findings in (iv) above.

When crops are grown on a piece of land for a long time, nutrients in the soil are reduced.
The nutrient content of such soil can be improved by adding fertilisers to the soil.
When added to the soil, fertilisers replenish nutrients used by plants or those lost during soil erosion and leaching.

Types of fertilisers
There are two types of fertilisers. These are:
(a) Natural (organic) fertilisers
(b) Artificial (inorganic) fertilisers

Natural fertilisers
Natural fertilisers are also called manure.
They are grouped according to the way they are prepared.
Examples of organic fertilisers are:

(a) Organic mulches,                (b) Farmyard manure,
(c) Green manure,                    (d) Compost manure

(a) Green manure
Green manure is formed from green plants.
Plants that are almost flowering are chopped and buried into the soil. When they decompose, they form green manure.

(b) Farmyard manure
Farmyard manure is also called animal manure. It is made from animal droppings,
dung, urine and their beddings.

Farmyard manure should be heaped in a shed and protected from the hot sun and excess rain water.
The manure should be allowed enough time to rot before it is applied to crops.

(c) Compost manure

Activity 9.3: Preparation of compost manure

Materials needed:
• Degradable waste from the class bins such as paper and fruit peelings.
• School kitchen refuse e.g. potato peelings and food remains.
• Maize stalks, grass and other dry materials.
• Farmyard manure
• Top soil
• Wood ash

What to do:
(i) Make a trench in the ground using a hoe and a spade.
(ii) Put maize stalks and other dry materials in the trench as the first layer.
(iii) Add degradable materials from the class bin and kitchen waste (about 7 cm thick).
(iv) Add some farmyard manure (about 5 cm thick).
(v) Add some wood ash (about 7 cm thick).
(vi) Put top soil on top of the heap.
(vii) Repeat the arrangement in (ii), (iii), (iv) and (v) until the heap is 1.2 metres high.

Give reasons why the following materials are needed in making compost manure
(a) Top soil
(b) Wood ash
(c) Farm yard manure
(d) Degradable waste, leaves and kitchen refuse

Activity Question
1. Compost manure is made from plant remains, animal waste, wood ash, kitchen refuse and top soil.
The materials are put in a heap or pit then allowed to decay or decompose.Why are plants like beans, peas and soyabeans the best for making green manure?

The following picture shows what a compost heap looks like.

Compost manure should be allowed to decompose before it is used in the farm.

Chemical fertilisers
Chemical fertilisers are also known as artificial fertilisers or inorganic fertilisers.
They are made from chemicals.
They have a high concentration of specific nutrients.
These fertilisers can be classified into two major groups straight fertilisers and compound fertilisers.

(a) Straight fertilisers
Straight fertilisers are fertilisers that contain only one major type of nutrient.
Examples include urea, single super phosphate among others.

Name 3 other examples of straight fertilisers.

(b) Compound fertilisers
Compound fertiliser are also called complex fertilisers. They contain two or
more major types of nutrients.
Examples of compound fertilisers include Diammonium phosphate (DAP) and
Calcium Ammonium Nitrate (CAN).

The following pictures show examples of compound fertilisers.

(a) Calcium Ammonium Nitrate                      (b) Diammonium Nitrate

        Fig. 9.9 (a) and (b): Examples of compound fertilisers.

9.3: I mportance of fertilisers

Activity 9.4: Investigating importance of fertilisers

Two farmers planted maize seeds on the same day. Their maize plants grew as shown below

(i) Which farm had fertile soil? Explain.
(ii) How does a farmer benefit from having healthy plants?
(iii) What can the farmer of Farm A do to make her maize plants healthy?
(iv) Describe how you can take care of your maize farm.
(v) What will happen if farmyard manure is exposed to direct sun and rain?
(vi) A certain farmer always applies decomposed farmyard manure on his crops. What might happen if he applies manure that has not decomposed on his crops?

Fertilisers are important in the following ways:
(a) They replace the nutrients lost through erosion or leaching.
(b) They help to increase crop yields.

(c) Inorganic fertilisers release their nutrients to crops very quickly. This makes crops grow fast.
(d) Organic fertilisers help to improve the physical properties of soil such as drainage, water retention and aeration of soil.
(e) Organic fertilisers help by introducing decomposers such as bacteria and fungi to the soil.

Rules of applying fertilisers

Activity 9.4: Application of fertilizer

Refer to the gardens that you prepared and planted maize in activity 1.1.
(i) Identify the appropriate type of fertiliser to apply: organic or inorganic fertiliser.
It is recommended to use organic manure before using inorganic fertilizer.

Procedure of applying nitrogenous fertiliser in the garden

(i) Choose the appropriate fertiliser for your farm.
(ii) Wear protective clothing; gumboots, gloves and an overall. This is to prevent direct contact of chemicals with the skin. They have a burning effect on the skin.

(iii) Read the manufacturer's instructions for directions on the amount to apply, how to mix the chemicals and mode of application.

(iv) Apply the fertilisers on the farm through top dressing (applied on the soil
surface at the base of the maize plant).

(v) Dispose of the empty containers of chemical fertilisers by burying deep into the soil or pit latrine.

(vi) Clean yourself thoroughly with soap and water.

NOTE: Organic fertiliser improves soil properties. They also release nutrients slowly; meaning the soil will retain its fertility for a longer time.

Class Project: To Investigate the effects of different fertilisers on plants

What is needed:
• Four equal plots of land.
• Coloured manila strings
• Maize seeds or sorgum seeds
• Hoes and rakes

What to do:
(i) Prepare the big plot for planting by digging and levelling.
(ii) Use a tape measure to divide the big plot into smaller equal plots A, B,C, D and E. Mark the plots using coloured manila string.
(iii) In plot A, apply DAP fertiliser in the holes where you will plant your maize seeds. In plot E, mix farmyard manure with soil before planting your seeds.

(iv) Plant maize seeds in plots B,C and D without using any fertiliser.
(v) Observe the appearance of your maize seedlings after three weeks.
(vi) When your maize plants are at knee height, apply fertilisers as outlined below.
      • In plot B, use nitrogenous fertilisers such as urea.
      • In plot C use phosphatic fertiliser.
      • In plot D use compound fertilisers such as CAN.

(vii) Compare the growth of maize plants in each plot. Record your observations in a project book.
(viii) Share the recorded information with other members of the class.
(ix) Once harvesting is done, compare the yields from each plot.

Points to note
     • Ensure that all your maize seeds are planted at the same time.
     • Ensure that you attend to the crops in all the gardens the same way.
For example watering, weeding and pest control should be done at the same time.

Activity Questions
1. Name: (a) Two fertilisers that are used during planting.
                (b) Two fertilisers that are used during weeding.
2. Consider a farm where maize has been grown continuously over several years and a farm where beans have been grown continuously for several years.
How will the fertility of the two farms compare?

Revision Activity 9

1. Match the characteristics of fertilisers given in (a) to the correct fertilizer in (b)

2. Identify steps of soil preparation for cultivation.
3. Why is it important to carry out secondary cultivation?
4. (a) What is the difference between organic and inorganic fertilisers?
    (b) Which fertiliser improves the quality of the soil? Explain.
5. The following pictures show chemical fertilisers.

(a) A is a ________ fertiliser.
(b) B is a ________ fertilizer.

6. Why is it advisable to add wood ash when preparing compost manure?
7. Outline the procedure of preparing green manure.
8. Compost manure can be made using the heap method or the pit method depending on weather conditions.
(a) Describe when the heap method is used and why.
(b) Describe when the pit method is used and why.
9. Farmer A keeps many animals while farmer B grows a lot of peas and beans.
(a) What organic fertiliser can farmer A make?
(b) What organic fertiliser can farmer B make?

(c) Give one disadvantage of fertilisers made in (a) and (b) above.
10. (a) Identify the following farm tools.

(b) From the tools given above, identify a tool suitable for:
(i) Clearing land.
(ii) Levelling the soil.
(iii) Ploughing a small piece of land.

11. (a) Fill two big containers with soil. Label them as (i) and (ii).
      (b) In (i) add farmyard manure and mix it with soil.
      (c) In (ii) add a chemical fertiliser like DAP.
      (d) Plant bean seeds in each container. Water the containers untilthe plants germinate.
      (e) Observe the bean plants as they grow. Write a report on how you have managed your                       plants.

Word list
1. Read the following words in pairs.
• Cultivation                       • Tilling                         • Harrowing
• Rake                               • Organic manure         • Chemical fertiliser
• Ploughing                       • Seed bed                    • Compost manure
2. Spell 3 words while your friend writes them in his or her notebook. Let your friend also spell 3 other words as you write them in your notebook.
3. Discuss with your friend the meaning of any 3 words in the word list.

Refer to notes in your textbook.