Use of saline irrigation waters and minimal leaching for crop production

An experiment in 24 lysimeters irrigated with water at three salinity levels is reported. Two crops—wheat and sorghum, were grown in the lysimeters, each of which contained one of four soil types—two clay loams and two sandy loams. Hydraulic conductivity, water potential, and water capacity were measured as functions of volumetric water content in nine of the lysimeters at the beginning of the experiment. Afterward, wheat, followed by sorghum and a second wheat crop, were grown while irrigated with water of 2.2, 4.2, or 7.1 mmho per cm electrical conductivity. There were no yield differences among treatments in the first wheat crop, because most of the growth was completed before yield-limiting levels of soil salinity were developed. Yields in the medium- and high-salinity treatments were reduced by 6 and 28 percent, respectively, compared with yield from the low-salinity treatment. Evapotranspiration was reduced 7 and 15 percent respectively, for the same treatments. Yield and evapotranspiration were substantially reduced in all treatments of the second wheat crops. The grain yield of the low-, medium-, and high-salinity irrigation treatments averaged 76, 72, and 54 percent of the corresponding yields in the first wheat crop. Salt precipitation averaged about 55 percent of the applied amount for all salinity treatments over the entire experiment. Profile salinization was still incomplete at the end of the third crop, a consequence of the low (10 percent) leaching fractions in all lysimeters.