Organic material (WRB)

Organic material is one of the diagnostic materials used, in the WRB system, to discriminate some soils from others.

Description

Organic material (from Greek organon, tool) consists of a large amount of organic debris that accumulates at the surface under either wet or dry conditions and in which the mineral component does not significantly influence the soil properties.

Diagnostic criteria

Organic material has one or both of the following :

• 20 percent or more organic carbon in the fine earth (by mass)

or :

• if saturated with water for 30 consecutive days or more in most years (unless drained), one or both of the following :
  • (12 + [clay percentage of the mineral fraction × 0.1]) percent or more organic carbon in the fine earth (by mass)
  • 18 percent or more organic carbon in the fine earth (by mass)

See also

• The FAO reference text, (2007 version)