Knowra Soil horizon Soil horizon A soil horizon is a distinct layer roughly parallel to the land surface, formed by soil development and distinguished by physical, chemical, or biological properties.
Soil profile : A vertical section through soil that displays its horizons from the surface downward. Horizons are the layers that together form this vertical sequence.
Eluviation : The removal of dissolved or suspended materials from a soil layer by downward or lateral water movement. Material lost from an upper horizon can accumulate lower in the profile.
Soil taxonomy : The United States Department of Agriculture system for classifying soils into hierarchical categories. Its diagnostic horizons help define many soil taxa.
O horizon : A surface soil horizon dominated by accumulated organic material. It exemplifies how plant litter and decomposition create a distinct surface layer.
Soil-forming factors : Climate, organisms, relief, parent material, and time jointly influence soil development. Their interaction produces the differences that distinguish horizons.
Illuviation : The deposition of materials transported from another soil layer, often by percolating water. It enriches some horizons with clay, iron, aluminum, or organic compounds.
World Reference Base for Soil Resources : The international system for naming and classifying soils using diagnostic properties and horizons. It uses diagnostic layers to distinguish major soil groups.
A horizon : A mineral soil horizon near the surface, commonly mixed with organic matter. It often marks the biologically active upper mineral layer.
Soil-forming processes : Physical, chemical, and biological processes that transform and redistribute materials in soil. These processes create, alter, and separate layers within a profile.
Soil leaching : The downward transport of soluble substances through soil by water. Leaching can deplete upper layers and change their chemical properties.
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