Soil: Soil Horizons and its Types

Soil

Soil is one of the most important natural resources. It supports varied life forms.

soil

Soil Profile

Soils are composed of different layers but how to recognize the order of different layers? To know the precedence of layers, we can perform an activity. Add some soil to a glass of water and allow it to settle. Refer the figure below.

Soil

The rotting dead matter in the soil is known as humus. Humus provides necessary nutrients to the soils.

Weathering – It is the process of formation of soils. Soils are formed by breaking down of rocks by water, wind and different climatic conditions.

A vertical cross section of different layers of soil is known as soil profile. Each layer has different texture, colour, chemical composition and depth. These layers are known as horizons.

Soil

soil

Weathering of rocks produces small particles of sand and clay. Mixture of sand and clay along with humus gives soil.

soil

Sandy soils have greater proportion of bigger particles. Clayey soils have higher proportion of fine particles. In loamy soils, the proportion of large and small particle is the same. Refer the figure below to visualize the difference between the structures of different types of soils.

soil

Soil

Percolation rate

Soil

Absorption of water by soils

Take 100 gm of water in a flask and start pouring it over the soil. Note the initial level of water. Keep pouring until the water starts dripping from the soil. Using the calculations below, we can calculate the percentage of water absorbed by soil.

Soil

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Practise This Question

Loam soil contains equal amounts of