Week Four
Subject: Agricultural Science
Class: Primary Four
Week of the Second Term: 4th Week
Topic: Soil Fertility Reduction – Causes
Subtopic: Causes of Soil Fertility Reduction – Burning
Instructional Objectives
At the end of the lesson, pupils should be able to:
- Define soil fertility and explain the concept of soil fertility reduction.
- Identify and describe the negative effects of burning on soil fertility.
- Suggest alternative farming practices that prevent soil fertility reduction caused by burning.
Entry Behaviour
Pupils should already know that soil is important for plant growth and understand basic concepts of soil fertility from previous lessons.
Instructional Materials
- Textbook (Agriculture for Primary Schools, Book 4)
- Visual aids (pictures showing fertile and burnt soil)
- Flashcards illustrating alternatives to burning (mulching, composting, crop rotation)
Reference Materials
- Dairo S.D., Akande A.S., Akindele F.Y., Muazu I., Uzowanne C. (2023). Agriculture for Primary School Book 4 (BEC Edition). Lagos: Spectrum Book Ltd.
- Youdeowei, A., Ogbazi, J.N., Adesiyan, S.O., Olowu, T. (2018). Wabp Primary School Agriculture Book 4. Lagos: West African Book Publishers Ltd.
Content
Causes of Soil Fertility Reduction – Burning
Introduction to Soil Fertility
Soil fertility refers to the ability of the soil to support plant growth by providing necessary nutrients. Healthy soil is essential for growing crops, plants, and trees. However, certain practices can harm the soil and reduce its fertility, meaning it can no longer support plant life as well as it should. One of these harmful practices is burning.
What is Burning?
Burning in farming is when people set fire to grasses, bushes, or crop residues in a field. This is often done to clear land quickly for planting or to get rid of unwanted vegetation. While it may seem like a fast solution, burning causes serious damage to the soil.
How Burning Reduces Soil Fertility
- Loss of Nutrients:
The top layer of soil contains essential nutrients like nitrogen, phosphorus, and potassium. When land is burned, the heat from the fire destroys these nutrients, making the soil less fertile. Without these nutrients, plants cannot grow properly. - Destruction of Organic Matter:
Organic matter in the soil comes from decomposing plants and animals. It helps to hold the soil together and provides nutrients for plant growth. Burning destroys this organic matter, which weakens the soil structure and reduces the amount of nutrients available for plants. - Soil Erosion:
After burning, the soil is left bare without any plants to protect it. This makes the soil loose and more likely to be blown away by the wind or washed away by rain, a process called erosion. Erosion removes the fertile topsoil, leaving the land barren and unable to support crops. - Killing Soil Organisms:
Healthy soil is full of living organisms like earthworms and bacteria that help break down organic matter and improve soil quality. When the land is burned, these beneficial organisms are killed by the heat, which further reduces soil fertility.
Why Burning is a Problem
Burning may clear land quickly, but the long-term effects are harmful. It reduces the soil’s ability to support plants and can turn fertile land into barren wasteland over time. Without fertile soil, farmers will have difficulty growing crops, which could lead to food shortages.
Ways to Prevent Soil Fertility Loss Due to Burning
- Use Crop Residues as Mulch:
Instead of burning leftover plants or grasses, farmers can leave them on the soil surface as mulch. Mulch helps retain moisture, adds nutrients to the soil as it decays, and protects the soil from erosion. - Practice Controlled Burning:
If burning is necessary, it should be done carefully and in small, controlled areas to minimize damage to the soil. Controlled burning should be followed by planting cover crops to protect the soil. - Adopt Alternative Land Clearing Methods:
Instead of burning, farmers can use tools like hoes and tractors to clear land. They can also use herbicides to kill unwanted plants without harming the soil.
Step 1: Introduction
Lesson Presentation (Step-by-Step Procedure)
Others removed.
