Overview of Soil Forming Factors

Process of Soil Formation

Soil formation or pedogenesis depends first on weathering. It is this weathering mantle (depth of the weathered material) that is the basic input for soil to form. Weathering is defined as the mechanical disintegration and chemical decomposition of rocks through the actions of various elements of weather and climate. First, the weathered material or transported deposits are colonized by bacteria and other inferior plant bodies like mosses and lichens. Also, several minor organisms may take shelter within the mantle and deposits. The dead remains of organisms and plants help in humus accumulation. Minor grasses and ferns may grow; later, bushes and trees will start growing through seeds brought in by birds and wind. Plant roots penetrate down, burrowing animals bring up particles, the mass of material becomes porous and sponge-like with a capacity to retain water and to permit the passage of air, and finally a mature soil, a complex mixture of mineral and organic products forms....

Overview of Soil Forming Factors

Five basic factors control the formation of soils:...

Parent Material

Parent material is a passive control factor in soil formation. Parent materials can be any in-situ or on-site weathered rock debris or transported deposits. Soil formation depends upon the texture and structure as well as the mineral and chemical composition of the rock debris/deposits. Nature and rate of weathering and depth of weathering mantle are important considerations under parent materials. There may be differences in soil over similar bedrock and dissimilar bedrocks may have similar soils above them. But when soils are very young and have not matured these show strong links with the type of parent rock. In the case of some limestone areas, where the weathering processes are specific, soils will show a clear relation with the parent rock....

Topography

Topography like parent materials is another passive control factor. The influence of topography is felt through the amount of exposure of a surface covered by parent materials to sunlight and the amount of surface and sub-surface drainage over and through the parent materials. Soils will be thin on steep slopes and thick over flat upland areas. Over gentle slopes where erosion is slow and percolation of water is good, soil formation is very favorable. Soils over flat areas may develop a thick layer of clay with a good accumulation of organic matter giving the soil a dark color....

Climate

The climate is an important active factor in soil formation. The climatic elements involved in soil development are...

Conclusion

Hence, we can conclude that soil is a mixture of rock debris and organic materials that develop on the earth’s surface. Various agents of gradation and weathering have acted upon the parent rock material to form a thin layer of soil....

FAQs on Soil Formation (Class 11 Geography)

What is soil?...