Cation Exchange Capacity - The ability of a soil to hold cations such as potassium, magnesium and calcium, on the surfaces of colloids in the soil. The higher the number, the more cations a soil can hold on exchange sites.
Cations held on exchange sites are readily available to the soil solution and, therefore, the plant.
Sandy soils usually have low CEC s of less than 5. Nitrates do not persist in soil. Once in the NO 3 form, they may be more easily leached from the rooting zone of most crops. Leaves will begin to die at the tips and will eventually die completely. Phosphorus is readily fixed in the soil to unavailable forms.