Education Always

Level: JHS, Basic 8  |  Subject: Integrated Science  |  Strand: Cycles  |  Topic: Crop Production

Curriculum reference: B8.2.3.1 Demonstrate understanding of soil fertility, maintenance and crop propagation. Indicator B8.2.3.1.1: Explain ways of maintaining soil fertility. All the exemplars are merged into one set of notes.

1. Soil Fertility

• A fertile soil has enough mineral salts (nutrients), water, air and humus for crops to grow well.
• Crops take nutrients from the soil, so a soil can lose its fertility when it is farmed again and again.
• Other causes of lost fertility: soil erosion, leaching (rain washing nutrients deep down), bush burning and over-grazing.
• Signs of poor soil: yellow leaves, stunted growth and low yield.

2. Ways of Maintaining Soil Fertility

Practice	How it helps
Crop rotation	Different crops are grown in turn on the same land. Legumes such as beans and groundnut add nitrogen to the soil.
Cover cropping	Low-growing plants such as mucuna or centrosema cover the soil, stop erosion, suppress weeds and add humus.
Application of manure	Animal dung, compost and green manure add humus and nutrients and improve soil structure.
Fertilizers	Chemical fertilizers such as NPK add nutrients quickly, but too much can harm the soil and rivers.
Fallowing	The land is left to rest so that it regains fertility.
Mulching	Dry grass or leaves on the soil keep it moist, cool and add humus as they rot.
Control of erosion	Terracing, contour ridging and planting trees keep the top soil in place.
Avoiding bush burning	Fire kills soil organisms and burns off humus.

3. Simple Soil Tests in the School Garden

• Soil type (feel test): rub moist soil between the fingers. Sand feels gritty, silt feels smooth and clay feels sticky.
• Water holding test: pour water on equal amounts of sand, loam and clay in funnels and compare how fast water drains and how much is held.
• Humus test: dark soil usually has more humus. Compare top soil with soil from deeper down.
• Soil pH test: use pH paper or an indicator to find out if the soil is acidic or basic.

4. Crop Propagation

Propagation means multiplying plants.

• By seeds: maize, groundnut, beans, tomato.
• By stem cuttings: cassava, sweet potato vine.
• By suckers: plantain and banana.
• By tubers and setts: yam, cocoyam.
• By budding or grafting: citrus, mango, cocoa.

Remember: Rotate crops, cover the soil, add manure, rest the land and stop erosion to keep the soil fertile.

Education Always (education.inspiringalways.com). Original notes written to follow the NaCCA Basic 8 Integrated Science curriculum.