Assessment of leaching of the salt-affected soils Using different levels of Pure and Acidic Water in Selected Regions of Mahabad Irrigation and Drainage Network

Improvement of saline-sodic soils is very important in terms of soil and water resources conversation. Accumulation and increasing of soil salts prevents plant growth and directly affects the crop yield. Soil salts reduction through the leaching and preventing from water logging is among the most important steps to prevent the negative effects of soil salinity. Improvement of saline-sodic soils depends on the quality and amount of applied water, type of amendment material and soil drainage condition. In this study, in order to evaluate how to improve the saline and sodic soils, randomized complete block design were conducted with different leaching treatments by using acidic and pure water in three levels of 25, 50 and 75 cm with three replications. After the soil moisture content reached to field capacity, soil samples were taken to analyze the changes of soil salts. Results indicated that, soil salinity and alkalinity class changed from S3A2 (high salinity and relatively high alkalinity) to S1A1 (low salinity and alkalinity) after leaching. The lowest and highest percentages of salinity and alkalinity improvement were related to the 25 cm of pure water and 75 cm of acidic water treatments, with average reduction of 24.7 and 41.2 percent for exchangeable sodium (ESP) and 25.9 and 69 percent for electrical conductivity (EC), respectively. In all treatments, differences between the use of the pure and acidic water were significant .This suggests that the amendment material is effective. Statistical analysis of results showed significant changes in ESP and EC parameters in 5 and 1 percent levels, respectively. Application of 50 cm acidic water was recognized as the most appropriate treatment in terms of water use and leaching efficiency. It could be recommended that, for efficient use of applied water, 50 cm acidic water to be used for remediation of soils in this region.