Comparative effects of chemical amendments on salt leaching from a saline-sodic soil in Kerman under laboratory condition

Most of lands in Kerman province are become saline and sodic, due to large amounts of salts in irrigation water sources. This is considered as one of the major limitations in the production of horticultural crops especially pistachio in recent years. The target of this study was investigation of the effect of different amendments of saline-sodic soil amelioration. Here, the effect of four treatments consist of irrigation water (control), gypsum, saturated gypsum and sulfuric acid was conducted four times in the laboratory condition based on CRD, using the soil column. Columns leaching was carried out intermittently and twice as much as the depth of the soil. Gypsum powder was completely mixed with the surface soil before starting leaching. Sulfuric acid and saturated gypsum were solved in irrigation water in separate containers. Changes in solute salt in drainage water from soil columns showed that the maximum amount of salts were removed from soil columns in the beginning of leaching and by continuing leaching process, reduced nonlinear to the constant concentration. There was no significant difference between gypsum and saturated gypsum treatments in sodium leaching, and these methods reduced the efficiency of leaching up to 30–40 percent. In the contrary, in presence of sulfuric acid the amount of sodium leached out of soil profile almost equaled that of the control treatment. Among all treatments, control treatment removed less amount of calcium and there for its remaining amount of calcium in the soil was more than other treatments. While in control treatment the amount of total removed salt was the highest. During leaching process, SAR changes in drainage water largely reflected the sodium changes and irrigation water compared to other treatments, as a control treatment with the highest amount of sodium removal, had the highest drainage water of SAR. Therefore, due to the great reduction in total salt, sodium leaching and no significant difference between control treatment’s pH and others treatment’s pH, it could be concluded that using irrigation water without application of amendments, plus considering economic issues, was a suitable strategy in successfully reducing both salinity and sodicity of the soil profile. On the other hand, due to the problem of water crisis in this region and removal of about 75% and 50% salts and sodium respectively at the beginning of leaching, irrigation water up to 1.1 times of soil depth can be recommended for the leaching of soluble salt from soil profile in this study area.