Soil Salt Accumulation and Crop Yield under Long-Term Irrigation with Saline Water

An experiment has been conducted to investigate the salt evolution process in soil and the response of crops to continuous irrigation with saline water under no artificial drainage from 2006 to 2013. A total of five salinity levels of saline water included 1.3, 3.4, 7.1, 10.6, and 14.1 dS/m, denoted as F1, F2, F3, F4, and F5. Results indicate that salt accumulation was significantly accelerated with the increased ratio of irrigation amount to precipitation (I/P), which was caused by higher annual irrigation times and irrigation quota, but soil salinity was reduced with the decline of I/P. Compared with initial soil salinity in 2006, final soil salinity in 2013 was decreased by 8.7 and 10.1% in the F1 and F2 treatments, but was increased by 7.3, 24.5, and 65.2% in the F3, F4, and F5 treatments. The peak salt values in the soil profile demonstrated a tendency to move up with the increasing salinity of irrigation water, suggesting that salt accumulated more readily in higher salinity treatments. Cotton yield in salinity treatments was close to that of fresh water (F1) when irrigation water salinity was below 7.1 dS/m, but reduced when irrigation water salinity was over 7.1 dS/m. The salt tolerance of forage rye was lower than that of cotton, and the relative forage rye yield dropped as soil salinity increased over the experimental years. Therefore, irrigation water salinity must be lower than 7.1 dS/m in cotton monoculture to keep the cotton yield close to that of freshwater treatment and reduce soil salt accumulation. DOI: 10.1061/(ASCE)IR.1943-4774.0000924. (C) 2015 American Society of Civil Engineers.