Response of crops to high exchangeable sodium percentage

Summary

Tolerance of crops to soil sodicity as represented by high exchangeable sodium has been examined utilizing data from field and greenhouse studies. A piecewise linear model has been utilized for describing the crop response curves. Salt tolerance indices including the threshold ESP, slope which represents yield decline per unit increase in ESP and the value of ESP at which yield is reduced by 50% are reported for 20 crops. In respect to threshold ESP, Sesbania is the most tolerant of the crops tested followed by rice (transplanted) and wheat. These are the only three crops in which threshold ESP exceeds 15. Genotypic differences for sodicity tolerance have been examined for rice and wheat, with CSR 3 — a natural selection among the rice genotypes — and Kharchia 65 among the wheat genotypes appear to be the most tolerant. The cumulative effect of ionic imbalance and water uptake are found to be the factors governing tolerance differences. The sodicity tolerance indices reported herein represent the relative sodicity tolerance of crops to high exchangeable sodium and could be used in management and crop planning in amended sodic soils and/or management of sodic waters.