Effects of saline water irrigation on soil salinity and yield of summer maize (Zea mays L.) in subsurface drainage system

Sustainable development of saline water irrigation was restricted by salt accumulation in the soil profile without appropriate salt discharging measures. A two year study was conducted in 2014 and 2015 to identify the effect of saline water irrigation on soil salt and maize yield under subsurface drainage system. The treatments of this study comprised three levels of water salinity with 0.78, 3.75, and 6.25 dS m−1 (S1-S3) and three levels of subsurface drainage depth with no subsurface drainage, drain depth of 0.8 m and 1.2 m (D0-D2). Results indicated that the average salt content within the root zone was in the order of D0 > D2 > D1. No salt accumulation occurred during the two growing seasons under D1, but there was salt accumulation under D2S3. Soil desalinization efficiency reduced with the increasing of irrigation water salinity, and the average desalinization efficiency for D1 was higher than that of D0 and D2. Maize yield and water use efficiency decreased with the increase of water salinity. The yield decreased by 2.08-3.01% for every 1 dS m−1 increase in salinity level of irrigation water under D1, and 3.53-3.93% for every 1 dS m−1 under D2. The effects of water salinity and drainage depth on maize yield and WUE were significant (p < 0.05) in the two growing seasons. From the view points of relative yield and soil salt balance, it can be recognized even as the salinity level of irrigation water is as high as 6.25 dS m−1, saline water can be applied to irrigate maize under drain depth of 0.8 m.