The Combined Effect of Drip Irrigation Quality and Nitrogen Fertilization on Soil Salinity and Na+ and Ca2+ Concentration in Soil Water

【Objective】 Drip irrigation using brackish water is a way to relieve water shortage in arid regions such as Xinjiang, but it needs a good management to reduce its detrimental consequence. The aim of this paper is to investigate the combined effect of irrigation water quality and nitrogen fertigation on changes in soil salinity and Na+ and Ca2+ concentration in soil water with cotton planted. 【Method】 A pot experiment was conducted from June to October 2020 at Alaer in Xinjiang. There are three nitrogen treatments: 255 kg/hm2 (F1), 315 kg/hm2 (F2) and 375 kg/hm2 (F3), and three irrigation water quality treatments: 1.27 g/L (Q1), 3.03 g/L(Q2), 4.90 g/L (Q3). Irrigation with groundwater was taken as the control. In each treatment, we measured soil salt content, and concentration of Na+ and Ca2+ in soil water. 【Result】 Depending on nitrogen fertigation, saline water irrigation increased total soil salt content and Na+ and Ca2+ concentrations by 14%~78%, 42%~197% and 58%~253%, respectively, compared to groundwater irrigation. It also increased soil sodium adsorption ratio (SAR) and exchangeable sodium percentage (ESP) by 5%~109% and 48%~90%, respectively. Increasing nitrogen application to 315 kg/hm2 and 375 kg/hm2 reduced soil salinity and Na+ and Ca2+ concentrations by 11%~70%, 6%~42% and 21%~138%, respectively, and reduced soil SAR and ESP by 5%~27% and 3%~19%, respectively, compared to the control. 【Conclusion】 Soil salinity increased with the increase in irrigation water salinity, but increasing nitrogen application to 315 kg/hm2 could reduce soil salinity and Na+ and Ca2+ concentrations in soil water, thereby alleviating salinity stresses.