Back to: Agricultural Science Primary 5
Hello, we are learning about Soil Formation today.
TOPIC: AGENTS OF SOIL FORMATION
In the last lesson, we started learning about soil formation. We learnt that soil is formed through a process called weathering. In this lesson today, we will focus on the agents that cause soil formation.
Agents of soil formation
The agents, whose activities lead to soil formation, are rain, wind, temperature, man, animals and plants.
Rain: Rain is water that falls in drops from (rain-making) clouds in the sky. When rain falls on mountains and hills, it washes downhill the broken rock particles, which help to form soil at their bases. It also breaks them down into rock particles. The rock particles, which are dark in color, mix with organic matter to form humus. This type of soil is very fertile and is good for growing crops. Rain also falls on dead plants and animals, and helps in their decay to form soil.
Wind: Wind blows on surfaces of hills and mountains. The force of the wind makes particles fall off the hills and mountains to form soil elsewhere.
Temperature: Temperature is the measure of how hot or cold the atmosphere is at a particular time of the day or night. When the atmosphere is hot, hills and rocks expand. When the atmosphere is cold, hills and rocks shrink or contract. Those changes create cracks on the surface of hills, rocks and mountains. In the process, small particles fall from the surfaces of the hills, rocks and mountains to form soil.
Man: Man breaks up rocks with pickaxes or hammers. The small pieces of the rocks collect to form soil. Man also uses heavy machines to crack rocks into small pieces which form soil.
Animals: Some animals dig holes in the ground and live there. When animals dig holes in the ground, they cause physical damage to rocks to form soil. Examples of such animals are the rat, cricket and the earthworm. These animals may carry some dead leaves and grasses into the holes as beddings. When rain falls on them, these dead materials decay to form soil.
Plants: Plants grow in the soil. They drop their leaves, including dead ones, on the ground. When rain falls, the leaves decay to form soil. Plants also die and decay to form soil. Some trees grow in-between rocks. Their roots help to break up rocks into particles that form soil.
EVALUATION
- What are agents of soil formation?
- List five agents whose activities bring about soil formation.
ASSIGNMENT
- Explain how the activities of the following bring about formation of soil.
- Rain
- Animals
- Temperature
- Plants
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