Soil forming factors

Soil forms as a result of  five soil forming factors. Differences in soil type within and between regions are a result of the interactions between these factors:

• Climate (cl)
• Organisms (o)
•  Relief (r)
•  Parent Material (p)
•  Time (t)

Climate

Climate influences soil formation through temperature; accelerating or slowing down chemical reactions and biological activity. High rainfall causes a downward movement of minerals or organic components through the profile, a process called leaching. Where annual rainfall is low, evaporation dominates and biological activity will be low or absent.

Organisms

Plant and animal organisms are important determinants of soil formation; in certain situations human beings have had an overwhelming influence the soil produced (e.g. Technosols and Anthrosols).

Relief or landscape position

Position on the landscape has an important influence upon soil development. On upper slopes soils may suffer from water erosion whereas water may accumulate in lower positions in the terrain (e.g. hill top versus valley floor). A related sequence of soils on a slope is referred to as a catena.

Parent material

Parent material is the geological source material from which a soil develops by weathering. Its nature influences the mineral content of the soil. Plants and organisms are the source of organic matter.

Time

Soils go through development phases; there are young soils and there are old, or weathered, soils. On ancient plateau surfaces in the tropics that have been subjected to very long periods of weathering, deep and strongly leached soils dominate. These are classified as Ferralsols.