The sets of basic exchangeable cations in soil samples can be divided into subsets by changing the conditions under which their displacement takes place. Using a large cation (cholinium) in a nonaqueous solvent (alcohol), primary subsets of exchangeable calcium, magnesium and sodium are displaced. When ammonium ion in an aqueous solvent is used after this primary displacement, a conditionally exchangeable subset is obtained. Potassium is almost completely conditionally exchangeable in the soils studied. The conditional subsets may be further divided depending on whether the condition of using a smaller displacing cation (NH4+) or of having water present is met first. The concept of partition by exchange conditions is distinct from a partition based on exchange constants (under unchanged conditions) to which the epithets easily and difficultly exchangeable are appropriate.