Chapter 1 - Fundamentals of Soil Science

Soil Science

Is the study of soil as a natural resource, encompassing its formation, classification, mapping, physical, chemical, biological, and fertility properties, and its use and management.

1. Pedopology

2. Edaphology

Branches of Soil Science

Pedology

It deals with soil formation, soil genesis, soil classification and description of soil properties

Pedologist

Studies, examines and classifies soils as they occur in their natural environment

Edaphology

Is the study of soil in relation to growth, nutrition and yield of crops or plants

Edaphologists

Consider the various properties of soils in relation to plant production

1. Alluvial Soil

2. Black Soil

3. Desert Soil

4. Red Soil

5. Laterite Soil

What are the types of Soils?

Alluvial Soil

Is a loose soil or sediments created by precipitation erosion. It is the most widely spread and important soil. They are formed by deposition of materials or sediments (alluvium) brought down by rivers that consists of silt, sand, clay, etc., that spreads across the river plains

Alluvial Soil

It is rich in potash, phosphoric acid and lime, making it suitable for growing rice, wheat, sugarcane and other cereal crops. Due to its high fertility, areas having this soil are intensively cultivated and densely populated.

Black Soil

This soil is black in color and is best for growing cotton and sugarcane. This soil is formed by the weathering up of igneous rocks. It is rich in minerals like iron and magnesium.

Dessert Arid Soil

These are sandy, porous and saline in nature. They lack humus and moisture. Hence, they are not suitable for cultivation except in areas where irrigation is available.

Red Soil

Develops on crystalline igneous rocks in areas of low rainfall. This soil is rich in iron compounds and is reddish in color while it is yellowish in color when it occurs in hydrated form.

Laterite Soil

These soils are formed by the intense leaching in tropical regions where the rainfall is high. This soil is devoid of nutrients and has low humus content and is not suitable for crop cultivation.

Soil as a Medium for Plant Growth

The soil can be viewed as a mixture of mineral and organic particles of varying size and composition in regard to plant growth.

The particles occupy about 50 percent of the soil's volume. The remaining soil volume, about 50 percent, is pore space, composed of pores of varying shapes and sizes.

The pore spaces contain air and water and serve as channels for the movement of air and water.

Pore spaces are used as runways for small animals and are avenues for the extension and growth of roots. Roots anchored in soil support plants and roots absorb water and nutrients.

For good plant growth, the root-soil environment should be free of inhibitory factors

1. Water

2. Nutrients

3. Oxygen

The three essential things that plants absorb from the soil and use are:

1. 25% Water

2. 25% Air

3. 5% Organic Matter

4. 45% Mineral Matter

What are the Ideal Soil Composition?

1. Formation of Parent Material

2. Evolution of Soil Layers

Soil formation, or the development of soils that are natural bodies, includes two broad processes: