Impact of irrigation volume and water salinity on winter wheat productivity and soil salinity distribution

Sustainable development of agriculture in the North China Plain is severely restricted by a shortage of fresh water. Saline water used for irrigation can increase crop yields as well as the risk of soil salinization. Therefore, to identify safe and simple ways of using saline water in this region, field experiments were conducted from 2011 to 2013 to evaluate the effect of irrigation volume and water salinity on winter wheat productivity and soil salinity distribution. A total of twelve treatments including four levels of irrigation volume (0.8E, 1.0E, 1.2E and 1.4E) and three levels of water salinity (3.3, 5, and 6.8 dS m−1) (S1, S2 and S3), were arranged in a randomized split-plot design with three replicates of each treatment. E is the total net pan evaporation that occurred after the irrigation. The results indicated that soil salinity increased at the harvest time of winter wheat under all of the treatments compared with initial conditions, particularly in the upper soil layers (0-40 cm). However, these impacts were eliminated by rainfall in summer and autumn. The effect of irrigation water salinity on yield was significant in the 2011/2012 growing season and non-significant in the 2012/2013 growing season (p < 0.05). Quadratic relationships were found between grain yield and irrigation volume for three water salinity levels in both growing seasons. The effects of irrigation volume on total water use (TWU), water productivity (WP) and irrigation water productivity (WPirrig) were significant. The interaction effects of irrigation volume and water salinity on grain yield, TWU, WP, WPirrig and soil salinity were statistically non-significant. The optimal irrigation volume per application was 0.98E, 0.98E and 0.92E for water salinities of S1, S2 and S3, respectively, by which more than 96% of the maximum yield and WP can be achieved.