Composition and properties of soil

Meaning of soil

Soil is the top layer of the earth's crust in which plant have root and from which they obtain water and mineral nutrients.

Soil is originally composed of bare rocks but due to the activities of various agent of weathering such as rain and wind, most rocks have crumbled or are weathered to produce soil particles.

Characteristics and properties of different types of soil

There are different types of soil, but the major ones are

(I) Loamy soil: Loamy soil is formed from the combination of sand and clay with a proportion of organic matter.

This type of soil is very fertile and is considered to be the best soil for agriculture

Characteristics

1. It is well aerated and hold water

2. It contains a lot of organic matter

3. It is loose and moist in nature

4. It does not support erosion and water logging

5. It is easy to cultivate and rich in plant nutrients.

(II) Clay Soil:A soil is said to be clayey if the proportion of clay in a sample of the soil is high. Clay is fine grained and holds much water and has the capacity of attracting and retaining plant nutrients

Characteristics

1. It has many pore spaces composed of very tiny pore .

2. It is poorly aerated and hold water.

3. It is finely grained and smooth.

4. Clay soil is sticky to touch and swells when wet and shrinks when dry.

5. Percolation is low but capillarity is high.

6. Clay soil is heavy.

7. It forms aggregates or lumps.

8. Clay soil consists of very small fine particles with the diameter less than 0.002mm.

(III) Sandy soil: Soil is said to be sandy when the proportion of the sand particles in the sample of soil are made up of over 50% coarse grain.

Characteristics

1. Sandy soil is coarse and gritty to touch.

2. Sandy soil is not sticky when wet.

3. It is well drained and aerated.

4. Sandy soil has large pore spaces.

5. It has poor water holding capacity.

6. It has no structure and therefore not suitable for plant growth.

7. It is easy to cultivate and therefore referred to as light soil.

8. It is easily heated up in the day time and cool fast in the night.

(IV) Silt soil: This consists of very small quartz particles. They micro sand grains but have more surface area than sand. Other characteristics include

1. The particles are smooth and powdery

2. It has high water holding capacity with most of the water available

3. Silty soil are fairly easy to till.

4. Silty soil contain smaller particles and pore spaces

5. Silty soil is of great importance of agriculture because it forms a naturally rich soil.

Properties of soil

1. Soil texture: refers to how a soil type feels when handled. It is the relative proportion of the different sizes of particles that make up a sample of soil.

2. Feel method: The texture of soil can be determined by rubbing each sample between the thumb and forefingers.

3. Moulding method: The sample of the soil is moistened and formed into ribbon. If ribbon can be formed into a circle, the sample is clay, but if it can be into u-shape is loam and if it does not form ribbon at all, then it is sandy soil.

4. Soil structure: Soil structure is the name given to the physical appearance of the soil depending on how individual soil particles or components are packed.