How Is Soil Formed?

Soil is formed when organic matter accrues and colloids are washed downward to deposit substances like clay, humus, carbonate, gypsum and iron oxide, which form a separate layer called the B horizon. This formation results from the effects of biological, chemical and physical processes that act on soil parent material, such as rocks.

The process and progress of soil formation is influenced by five major factors: parent material, topography or relief, climate, time and organisms. Parent material is the original mineral material that eventually forms soil. Parent material weathers through physical and chemical processes as rocks disintegrate and mix with water to form soil components. Climatic factors, such as changes in temperature, influence the physical and chemical processes and affect soil formation. Topography, which is the inclination of the land, may slow or speed up the movement of particles. Organisms like plants and animals, through their daily lives, affect the formation of soils. Animal activities, such as movements on the surface, tamper with the natural formation of soils. The elements are moved from one level to the next with the help of water and animal activities, resulting in the formation of layers within the soil profile. These movements lead to the formation of soil horizons.