PRIMARY 4: AGRIC SCIENCES – FIRST TERM | WEEK 6

TOPIC: LOSS OF SOIL FERTILITY

A: TEACHING AND LEARNING MATERIALS

1. Pictures of healthy and unhealthy crops.
2. Samples of fertile soil.
3. Pictures of bush burning.
4. Pictures of soil erosion.
5. Farm charts.

B: REFERENCE MATERIALS

1. Scheme of work.
2. Recommended Agric Sciences textbook for Primary 4.
3. Online educational resources.

C: PREVIOUS KNOWLEDGE

The pupils have learnt the types and properties of soil and know that plants obtain water and nutrients from the soil.

D: PERFORMANCE OBJECTIVES

By the end of the lesson, pupils should be able to:

1. Explain soil fertility.
2. Explain loss of soil fertility.
3. State causes of loss of soil fertility.
4. Explain the effects of bush burning.
5. State effects of poor soil fertility on crops.

E: CONTENT

Meaning of Soil Fertility

Soil fertility is the ability of soil to provide enough nutrients for healthy plant growth. A fertile soil supports healthy crops. 🌱 Fertile soil → healthy plant

Loss of Soil Fertility

Loss of soil fertility occurs when the soil no longer contains enough nutrients to support healthy crop growth.

Causes of Loss of Soil Fertility

1. Continuous Cropping

Growing crops on the same land repeatedly without replacing nutrients makes the soil poor.

2. Bush Burning

Fire destroys dead plants and useful soil organisms. It also exposes the soil to erosion. 🔥 Bush burning can reduce soil fertility.

3. Soil Erosion

Erosion removes the fertile topsoil.

4. Leaching

Rainwater may carry nutrients deep into the soil where plant roots cannot easily reach them.

5. Removal of Vegetation

Cutting down too many trees and plants leaves the soil exposed.

6. Overgrazing

Too many animals feeding on the same land can destroy vegetation and expose the soil.

Effects of Loss of Soil Fertility

1. Crops grow poorly.
2. Leaves may become yellow.
3. Plants may be weak.
4. Harvest becomes smaller.
5. Farmers may lose money.

F: LESSON PRESENTATION

F1: Teachers’ Activities

1. Explains soil fertility.
2. Shows pictures of healthy and unhealthy plants.
3. Explains causes of loss of soil fertility.
4. Discusses bush burning and erosion.
5. Explains the effects of poor soil fertility.
6. Guides pupils to suggest ways soil can become poor.

F2: Pupils’ Activities

1. Explain soil fertility.
2. Identify healthy and unhealthy plants.
3. Name causes of loss of soil fertility.
4. State effects of bush burning.
5. State effects of poor soil fertility.

G: CONCLUSION

The teacher revises the meaning, causes and effects of loss of soil fertility. The teacher encourages pupils to avoid activities such as unnecessary bush burning that can damage farmland.

H: EVALUATION GUIDE

Pupils should be able to answer the following questions:

1. What is soil fertility?
2. What is loss of soil fertility?
3. State four causes of loss of soil fertility.
4. How does erosion reduce soil fertility?
5. State two effects of bush burning.
6. State three effects of poor soil fertility on crops.