Soil Salinity and Maize Growth under Cycle Irrigation in Coastal Soils

The coastal regions of eastern China have substantial potential for agricultural production. Freshwater scarcity makes the utilization of plentiful brackish water a vital issue in this area. We aim to assess the effects of cycle irrigation with fresh and brackish water on soil salinity and maize (Zea mays L.). A pot experiment was performed with two typical coastal soils (sandy loam and silt loam) and one local maize cultivar. The maize growing season was divided into three phases (development, mid-, and later stage). Cycle irrigation was conducted using brackish water (5 g NaCl L-1) during one stage and freshwater for the remaining stages. Cycle irrigation using brackish water at the development stage caused both osmotic and ionic stresses on the maize, leading to significantly-reduced evapotranspiration (ET), increased stem and leaf Na+/K+ ratio, and stunted growth. The decline of kernel number and 100-grain weight resulted in severe yield loss. Cycle irrigation with brackish water at the mid-stage induced less adverse effects on crop growth, while the decrease in kernel number remarkably reduced the yield. Cycle irrigation with brackish water at the later stage minimized the impacts of saline irrigation on soil salinity and maize productivity. Nonetheless, salt leaching by off-season rainfall and low salinity water and soil salt monitoring should be considered before the next season. Compared to sandy loam soil, silt loam displayed higher soil salinization, and lower maize growth and yield. Additional field research is recommended to facilitate the reliable use of coastal soil and water resources.