Cationenaustauschkapazität

Cationenaustauschkapazität, often abbreviated as CEC, refers to the total capacity of a soil or other material to hold positively charged ions, known as cations. These cations are essential nutrients for plant growth, such as calcium (Ca²⁺), magnesium (Mg²⁺), potassium (K⁺), and ammonium (NH₄⁺). The CEC is a measure of the soil's ability to retain these important elements and prevent them from leaching away with water.

The CEC is typically expressed in milliequivalents per 100 grams of soil (meq/100g) or centimoles of positive charge per kilogram of soil (cmol(c)/kg). Soil organic matter and clay minerals are the primary components responsible for a soil's cation exchange capacity. Organic matter, with its extensive network of negatively charged functional groups, and clay particles, which possess a net negative charge due to isomorphic substitution within their crystal structures, attract and hold onto positively charged cations.

Soils with higher organic matter content and a greater proportion of clay particles generally exhibit higher CEC values. This means they can hold more nutrient cations and are less prone to nutrient deficiencies. Conversely, sandy soils with low organic matter have a lower CEC and are more susceptible to nutrient loss through leaching. Understanding CEC is crucial in agriculture and environmental science for managing soil fertility, predicting nutrient availability to plants, and assessing the potential for groundwater contamination.