The upper layer of earth in which plants grow, a black or dark brown material typically consisting of a mixture of organic remains, clay, and rock particles.
Soil is the mixture of minerals, organic matter, gases, liquids and a myriad of micro- and macro- organisms that can support plant life. It is a natural body that exists as part of the pedosphere and it performs four important functions: as a medium for plant growth and of water storage, supply and purification; as a modifier of the atmosphere; and finally as a habitat for organisms that take part in decomposition and creation of a habitat for other organisms. Soil is considered the "skin of the earth" with interfaces between the lithosphere, hydrosphere, atmosphere, and biosphere.
Soil consists of a solid phase (minerals & organic matter) as well as a porous phase that holds gases and water.
Accordingly, soils are often treated as a three-state system.
Soil is the end product of the influence of the climate, relief (elevation, orientation, and slope of terrain), biotic activities (organisms), and parent materials (original minerals) acting over periods of time. Soil continually undergoes development by way of numerous physical, chemical and biological processes, which include weathering with associated erosion.