How is soil formed?


-Priyanti, Subject Matter Expert at Edumarz

Solution: Soil is the uppermost layer of the Earth’s crust that supports life. The parent material for the formation of soil are rocks. Rocks undergo weathering and natural erosion to break down into soil particles over thousands of years. Several factors affect the formation of soil, which includes:

  • Nature of parental material forming soil

  • Groups of living organisms residing in soils

  • Climatic conditions in the region of soil formation

  • Topography of the region of soil formation

  • Time available for the soil to form

A combination of all these factors is responsible for the nature of soil found in a particular area. 

Initially, rocks begin to disintegrate under the weather conditions such as extreme temperature fluctuations and heavy rainfall. Accumulation of water in the cracks formed upon degradation further weathers the rock; this water will freeze and thaw depending upon the weather, causing further damage upon the breaks. Growth and subsequent decay of plants on these rocks cause them to disintegrate even more, and organic acids released start mixing with the minerals in the rocks. Dissolution of these rock minerals in organic acid paves a way for the formation of new minerals and other compounds, so the chemical nature of the parent rock begins to alter. With time, it supports the growth of some microorganisms that further homogenize the forming soil. With the passage of time, soil matures and develops into something entirely different from its parental rock; it is now a mixture of minerals, organic matter (humus) and soil microorganisms.

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