Soil formation (also termed soil genesis or pedogenesis) is the set of dynamic processes by a soil forms, as determined by the characteristics of its environment (the soil-forming factors), over time since the deposition of the geological material upon which the soils form. Soil genesis is underlain by two major concepts.
- Soil properties result from the action and interaction of soil-forming (or pedogenic) processes.
- The type and intensity of these pedogenic processes are governed by environmental factors - the conditions of the natural world in which the soils occur and the impact of human activity on these environmental factors.
Pedogenesis leads to the development one or more distinct layers, which are formally called soil horizons. These layers may differ from each other in terms of their colour, structure, texture (the particles that compose it) or many other physical or chemical properties. A given set of horizons will result from the action and interaction of the environmental conditions, and these soil horizons will differ from place to place within a field and within a region or country. Hence the distribution of soil horizons and soil properties is not random - they are responding to a set of environmental controls.