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C horizon

Mineral horizon or layer, excluding indurated bedrock, that is little affected by soil-forming processes and does not have the properties typical of the overlying horizon. The material of a C horizon may be either like or unlike that in which the solum formed. If the material is known to differ from that in the solum, an Arabic numeral, commonly a 2, precedes the letter C.

Ca, calcium

CaO Ca x 1.39 = CaO


Process whereby the soil is kept sufficiently supplied with calcium to saturate the soil cation exchange sites.


Common Agricultural Policy.

Capability Classification System

A system developed by the usda natural resources conservation service of grouping soils based on their inherent suitability for intensive uses.

Capillary water

Water in capillary pores influenced by forces that hold water in soils against a tension usually greater than 60cm. Capillary water can move upwards against gravity.

Carbon cycle

Sequence of transformations whereby carbon dioxide is converted to organic forms by photosynthesis or chemosynthesis, recycled through the biosphere (with partial incorporation into sediments), and ultimately returned to its original state through respiration or combustion.

Carbon sequestration

The capacity of a soil store carbon in a non-labile form with the aim to reduce the CO2 concentration

Cash Crop

An agricultural crop grown to provide revenue from an off-farm source (

Catch crop

Non-harvested crop grown in between two main crop seasons, mainly intended to scavenge residual soil mineral N and thus potentially growing under N limitation.

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