Mass Balance Criteria in Soil Salinity Management: The Effect of Different Irrigation Water Qualities and Leaching Ratio

Özet

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 around the world. 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 outdoor , under alfalfa ( Medicago sativa L. ) cultivation, within PVC lysimeters, with a height of 115 cm and a diameter of 40 cm. Three irrigation water salinity (0.25, 1.5 and 3.0 dS m -1 ) 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, in total 36 lysimeters. 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. Among the major soluble anions, SO 4 2- leached out from the profile, yet HCO 3 - , and Cl - accumulated in the soil in various levels when the salinity content of irrigation waters increased. The increase in the leaching ratio (LF) caused the increase in the leaching of Cl - in the soil profile. The major cations, Ca 2+ , Mg 2+ , and Na + , in the soil were also evaluated for their total mass concentrations regarding salinity content of irrigation water and LF. Ca 2+ concentration in the soil profile increased with salinity level and the leaching ratio, whereas Mg 2+ , and Na + mass concentrations decreased considerably. Na + was leached because the Ca 2+ adsorption in the soil was stronger. The effect of LF on the ion mass accumulation or leaching varied depending on the ion type.