Effects of saline water irrigation on soil quality and crop production: a review

Fresh water is a basic natural and important strategic resource. Most salt-affected soils are distributed in arid and semi-arid areas, and a shortage of freshwater resources is the most important limiting factor for sustainable agricultural development. However, the relatively rich saline water, land, solar, and thermal resources in saline-alkali areas provide sustainable regional agriculture development potential. To address challenges of soil quality decline and crop yield reduction induced by saline water irrigation, this study summarizes the factors affecting the safe utilization of saline water and the impact mechanism of saline water irrigation on soil hydraulic characteristics, soil physicochemical properties, crop growth, grain yield, and quality. First, freshwater, brackish water, and saline water classifications were as previously described. Factors affecting the safe utilization of saline water include saline water quality, irrigation amount, irrigation methods, and the groundwater table. Second, saline water irrigation has negative effects on soil quality, which increases the salinity of the surface soil, destroys the soil structure, and further affects the soil hydraulic characteristics, water infiltration, and salt distribution, affecting greenhouse gas emissions. Third, crops grow slowly and die because of the lower photosynthetic rate after saline water irrigation. However, most of the treatments irrigated using saline water improved the grain yield compared with the rainfed treatment and improved the grain quality under optimal salinity water. Furthermore, based on field experiments, most crops have optimal saline water thresholds. Finally, we analyzed the regulatory effects of agricultural practices such as organic fertilizer application, straw mulching, tillage, saline water irrigation schedules, cropping systems, and salt-tolerant crop planting. In the future, to ensure food and water security, it is necessary to conduct the mechanism process and technology research, and develop model to demonstrate the effects of saline water deficit irrigation and water-fertilizer-salt comprehensive regulation on the change in soil quality after saline water irrigation, and the effects of saline water precision irrigation on crop production and the ecosystem, which will provide a theoretical basis and technical support for the sustainable development of agriculture in water-deficient and saline areas.