Sudan (Sorghum sudanense P. Stapf) and tall fescue (Festuca arundinacea Schreb.) grasses were grown in outdoor lysimeters with various irrigation water salinity levels and leaching fractions to determine the steady‐state salt profiles that developed and to relate the salt profiles to yield. Yields of both grasses were highly related to the average salinity of the root zone in spite of marked differences in vertical distribution of salt. The first increments of leaching were the most effective in preventing salt accumulation in the root zone. These results agree with those previously reported for a similar study with alfalfa (Medicago sativa L.). The observed leaching fractions required to achieve 90% of maximum yields of all three crops with 2‐ and 4‐mmho/cm irrigation waters agreed reasonably well with values calculated by the equation: LF = EC1w/ECe‐50 per cent, where LF is leaching fraction, and EC1w and ECe‐50 per cent are the electrical conductivities of the irrigation water and of the soil saturation extract at 50% yield decrease, respectively.