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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.


Particle with positive charge; reactions between anions and cations create electrical forces.

Cation exchange

Interchange between a cation in solution and another cation in the boundary layer between the solution and surface of negatively charged material such as clay or organic matter.

Cation exchange capacity (CEC)

The capacity of soil to hold nutrients for plant use. Specifically, CEC is the amount of negative charges available on clay and humus to hold positively charged ions. Effective cation exchange capacity (ECEC) is reported for acid soils (pH<5). Expressed as centimoles of charge per kilogram of soil (cmolc/kg).


Soil particles less than 0.002 mm in diameter with high specific area mainly influencing soil colloidal properties (see also colloid) as well as stability of soil structure: high stability in both wet and dry conditions OR a soil textural class with 40% or more clay, less than 45% sand, and less than 40% silt.

Clay coating/film

Coatings of oriented clay on the surfaces of peds and mineral grains and lining pores, also called clay skins, clay flows, illuviation cutans, or argillans.

Clay loam

Soil texture class. See also soil texture.

Clay minerals

Clay-sized hydrous aluminium silicates having a large interlayer space that can hold significant amounts of water and other substances; they have large a surface area allowing swelling and shrinking; examples are montmorillonite or smectite and kaolinite.

Climate change adaption

Adaptation means anticipating the adverse effects of climate change and taking appropriate action to prevent or minimise the damage they can cause, or taking advantage of opportunities that may arise. It has been shown that well planned, early adaptation action saves money and lives later. (

Climate change mitigation

Refers to efforts to reduce or prevent emission of greenhouse gases. Mitigation can mean using new technologies and renewable energies, making older equipment more energy efficient, or changing management practices or consumer behavior. (

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