Mass balance criteria in soil salinity management: different irrigation water qualities and leaching ratio

Abstract

The accumulation of excess soluble salts in the root zone of arid and semiarid irrigated soils is a widespread problem that seriously affects crop productivity. The cultivated soil profile under irrigation is the main media in which the salinization occurs. In this study, the effects of different irrigation water salinity and leaching ratio on soil profile salt mass balance changes were investigated in alfalfa (Medicago sativa L.) cultivated PVC lysimeters (115 cm in height and 40 cm diameter). Three irrigation water salinity (S1, S2, and S3, 0.25, 1.5 and 3.0 dS m -1, respectively) and four leaching ratios, LF, (10%, 20%, 35% and 50% more water than ET) levels were used in a fully randomized factorial design experiment with three replications. The total salt mass balance was calculated from the subtraction of total salt mass concentration supplied with irrigation water and total salt mass concentration washed out with the drainage water. When the salinity content of irrigation water increased leaching of SO4 2and Claccumulation in the soil increased. Increase in the leaching ratio (LF) caused increase in the leaching of Clthrough the soil profile. The major cations, Ca2+, Mg2+, and Na+, in the soil were also evaluated for their total mass concentrations regarding salinity content of irrigation water and LF. Ca2+ concentration in the soil profile increased with salinity level and the leaching ratio, whereas Mg2+ and Na+ mass concentrations decreased considerably. This is due to the high Ca2+ adsorption in the soil than that of Na+. The effect of LF on the ion mass accumulation or leaching varied depending on the ion type.