What are the major factors of soil formation ? Explain.

1. Parent material : The parent material is derived from the rock exposed to the weathering agents. It determines the types, colour and structure of the soil. Its fertility also depends upon, the constituents of the rock. For example, the soil which is formed by lava, is black and has rich fertility.

Moreover, if the soil is deposited by running water, it has little relation with surface rock. For example, the soils of plains of India are deposited by the rivers flowing from the Himalayan and plateau regions. They consist of fine grains of loamy, sand and clay. Hence, they have high degree of fertility.

On the other hand, soils of the plateau regions are poor. They are closely related to the parent rocks. They are coarse-grained and less fertile.

2. Relief features : The relief features affect the soil formation in various ways. The variation of slope of land determines the degree of its deepness and fertility. If the slope is steep, the

soil cover is thin or shallow and less fertile due to intensive erosive activity there. On the other hand, if the slope is gentle or low the soil cover is deep and rich in its fertility. Because of this reason, the soils of plains and river basins are rich and deep while the soils of the plateau regions are poor and shallow. Hence, the degree of slope largely determines the fertility of the soils.

3. Climate : The elements of climate such as temperature and rainfall affect the soil formation through their amount and seasonal distribution. Climate determines the type of soil and the effectiveness of weathering of the parent rock material, the quantity of water seeping through the soil and the type of micro-organisms present therein.

4. Natural vegetation : The natural vegetation provides the much needed content of humus through its decayed leaf. Hence, the dense forestlands of our country have rich soils.