Soil: Meaning, types, composition and properties of soil

CONTENT

• Meaning of Soil
• Types of Soil
• Composition of Soil
• Properties of Soil

MEANING OF SOIL

Soil can be defined as the unconsolidated weathered materials found in the upper most layer of the earth surface on which plants grow. It provides support and nutrients for the plants.

TYPES OF SOIL

The three types of soil are; Sandy Soil, Clay Soil and Loamy Soil.

SANDY SOIL

A soil is said to be sandy if the proportion of sand particles in a sample of the soil is high. The particles are mainly quartz (SiO2).

PROPERTIES OF SANDY SOIL

1. Sandy soil is coarse, grained and gritty.
2. It is loose with large pore spaces.
3. It absorbs and loses water easily.
4. It is not sticky when wet and cannot form a cast or ribbon.
5. It is well aerated with low water holding capacity.
6. Percolation in sandy soil is high but capillarity is low.
7. Sandy soil heats up easily during the day and cools down quickly in the night.
8. It supports leaching, hence it is low in plant nutrients.
9. It does not support water logging and erosion.
10. Sandy Soil has grey or brownish colour.

METHODS OF IMPROVING SANDY SOIL

1. Planting of cover crops
2. Application of compost manure
3. Application of farm yard manure
4. Mulching the soil
5. Avoidance of bush burning

ECONOMIC IMPORTANCE OF SANDY SOIL

1. It is good for cultivation of cassava, cotton, groundnut etc.
2. It is good for building construction when mixed with cement.

EVALUATION

1. What is soil?
2. List the three types of Soil and state three characteristics of sandy soil.

CLAY SOIL

A soil is said to be clayed if the proportion of clay in a sample of the soil is very high.

PROPERTIES OF CLAYED SOIL

1. The particles are fine, powdery and smooth when dry.
2. The parties are sticky and moody when wet.
3. The particles are tightly bound together with little pore (air) spaces.
4. It has a high water holding capacity.
5. It is poorly aerated.
6. Percolation in clay is low but capillarity is high.
7. It does not support leaching, hence it contain plant nutrients.
8. It is hard when dry and sticky when wet.
9. It can easily form a ribbon or cast when molded.
10. It supports water – logging and erosion.
11. It has a grey or brownish colour.

METHODS OF IMPROVING CLAYED SOIL

1. Liming
2. Addition of organic manure

EVALUATION

1. What is clay soil?
2. In a tabular form, give five differences between sandy and Clay soil.

LOAMY SOIL

Loamy soil is a mixture of sand and clay particles with high proportion of organic matter.

PROPERTIES OF LOAMY SOIL

1. Loamy Soil is moist, loose with moderate sized pore space.
2. The structure breaks easily when wet and friable when dry.
3. It has non-powdery and non-sticky texture.
4. It can easily be worked or cultivated.
5. It contains lots of organic matter (humus).
6. It does not support erosion and water logging.
7. It was well aerated and it can hold water.
8. It is the best soil for cultivation of crops.
9. It is dark brown or black in colour.

EVALUATION

1. What is loamy soil?
2. List four properties of loamy soil.

COMPONENT/COMPOSITION OF THE SOIL

The composition of the soil by percentage are:

1. Soil mineral matter                 45%
2. Soil water                                25%
3. Soil air                                     25%
4. Soil living Organisms             5%

GENERAL EVALUATION

1. List two methods of improving clay soil.      
2. List the component of soil and their respective percentage composition.
3. List three ways of improving sandy soil.
4. List five properties of sandy soil.
5. List five properties of clay soil.

READING ASSIGNMENT

Essential Agricultural Science for Senior Secondary Schools by O.A. Iwena pages 65-87.

WEEKEND ASSIGNMENT

1. Particles of soil care closely packed together in ____ soil  (a) sandy (b) clay

(c) loamy (d) silt

• Quartz is the major composition of ____ soil (a) clay (b) loamy (c) sand (d) silt
• The soil which mostly which mostly support leaching is ____ (a) sand (b) clay

(c) loamy (d) silt

• The soil which supports water logging is ____  (a)  sand (b) silt (c) clay (d) loamy
• The best soil for agriculture is ______ (a)  sand (b) clay (c) silt (d) loamy

THEORY

1. (a) What is a soil?

            (b) List the four component of soil.

2.         (a) State four characteristics of clay soil.

            (b) What is weathering?