The sodium adsorption ratio (SAR) is an irrigation water quality parameter used in the management of sodium-affected soils.
SAR allows assessment of the state of flocculation or of dispersion of clay aggregates in a soil.
Sodium and potassium ions facilitate the dispersion of clay particles while calcium and magnesium promote their flocculation.
[4] The concept of SAR addresses only the effects of sodium on the stability of soil aggregates.
[5] To take into account simultaneously all major cations present in water, a new irrigation water quality parameter was defined: the cation ratio of structural stability (CROSS), a generalization of SAR.