Lesson Notes By Weeks and Term - Primary 4

WEEK 5&6

TOPIC: PROPERTIES OF SOIL

PERFORMANCE OBJECTIVES

At the end of this lesson, Pupils should be able to know:

Mention the properties of loamy, sandy and clayey oil.

Explain the ways of enriching and maintaining soil fertility.

ENTRY BEHAVIOUR/ PREVIOUS KNOWLEDGE: Pupils are familiar with the characteristics of types of soil.

REFERENCE MATERIALS

Universal Basic Education Curriculum.

NERDC Basic Education Curriculum for Primary Schools.

Unified Schemes of Work Primary Schools four Agricultural Science (MIDDLE BASIC)

Internet.

Lagos State Agricultural Science Scheme of Work

Agricultural Science for Primary Schools.

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CONTENT�

Physical properties of soil

Each soil type has some physical properties. The property of any soil type is what makes it different from the others.

Sandy soil

This soil is different from clay and loam in many ways. Sandy soil contains tiny stone particles. It is rough when rubbed between the fingers, and it runs freely through the fingers when dry. It is found mostly along footpaths, deserts and erosion areas. It is loose and not that fertile.

CLAYEY

Clayey soil is slippery and sticky when wet. When dry, clayey soil is hard, very smooth, feels like powder, and it cracks. Have you seen a cracked soil before? That is clay. Clay is a bit fertile.

LOAMY SOIL

This soil has properties that are different from sand and clay. Loamy soil has a mixture of the properties of sand and clay. It is very rich in humus. It is, therefore, fertile and the best for farming.

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How to enrich the soil

Causes of loss of soil fertility

Soil is said to be fertile when all the nutrients necessary for plant growth and development are present in it. Soil can lose its fertility in five main ways:

In some places, big forests and vast grasslands are set on fire to burn. Some of these areas are good farmlands. When this is done, dead and decaying leaves, grasses and living soil organisms are burnt. Dead leaves, grasses and soil organisms add fertility to the soil. Soil, therefore, loses its fertility when they are burnt.

Leaching

This is the downward movement of nutrients from the top soil to the underground layers of the soil. Some nutrients dissolve in water for plants to absorb as food. When rain falls, some water collects in low-lying areas of the farm and stays there for some time. As this water sinks into the soil, it carries with it dissolved soil nutrients. These nutrients can no longer be available to the plants growing On the surface of the soil. The nutrients are lost or leached away.

Erosion

This is the gradual wearing away of the top soil by water or wind. When rain falls, water flows on the surface of the soil. The water carries the top soil along with it. The top soil contains nutrients dissolved in water. These nutrients are carried away by the flowing water and are no longer available for plants to use.

�Wind blows and carries some soil particles from one place to another. This soil contains some nutrients which are also carried away by the wind.

Crop removal

The crops that farmers plant in their farms absorb nutrients from the soil for their growth and development. These nutrients, once taken up or absorbed, are no longer in the soil. Another crop planted in the same soil the following year may not have sufficient nutrients for its own growth and development.

Clean clearing

Leaves on forest trees drop on the soil. These leaves die and decay, and add nutrients to the soil. When these trees are removed and the forest undergrowths cut, the soil loses its regular supply of nutrients from the forest.

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INSTRUCTIONAL PROCEDURE

The Teacher revises the previous lesson.

The Teacher introduces the topic.

The Teacher explains the lessons.

LEARNERS ACTIVITIES

Learners participate in the class discussion

Learners observe some rock samples

EVALUATIVE ACTIVITIES

Mention the properties of loamy, sandy and clayey oil.

Explain the ways of enriching and maintaining soil fertility.

CONCLUSION: the teacher summarizes the lesson.