Influence of Alternating Freshwater and Saline Water Irrigation on Water-salt Distribution and Maize Yield in Shallow Groundwater Regions

Abstract

【Objective】 Many arid and semiarid regions in North and Northwest of China are poor in freshwater but have saline groundwater. Efficient utilization of these saline waters is crucial for agricultural sustainability. This study seeks to experimentally identify the optimal alternation of freshwater and saline water for irrigating arable crops in areas with shallow groundwater. 【Method】 The experiment was conducted at a maize field from May to October in 2022 at an experimental site in Darat Banner, Erdos. It compared four irrigations: irrigating with saline water only (T1), irrigating with saline water twice followed by a freshwater irrigation (T2), irrigating with saline water once followed by one freshwater irrigation (T3), irrigating with freshwater only (CK). In each treatment, we measured water and salt distribution in the soil, as well as yield of the maize. 【Result】 Alternate irrigation significantly influenced soil moisture and salinity. T3 considerably increased root water uptake during the critical growth stage of the crop, manifested by the 0.75% to 1.3% reduction in water content in the 0~40 cm soil layer, and 2.02% to 3.71% increase in water content in the 40~100 cm soil layer. During the irrigation period, there were 58.45% and 63.98% of soils salinized in T2 and T3, respectively. Compared to CK, alternate irrigation reduced crop yield by 10% to 13%, but saved 33% to 50% of freshwater. Grain yield and water use efficiency of T3 were 90.26% and 23.2% higher than that of T1, respectively, despite its 7.2% reduction in grain yield compared to CK. Groundwater recharge during the reproductive period accounted for 21.74% to 25.55% of the water consumed by the maize. 【Conclusion】 Considering the effect of alternate irrigation on distribution of water and salt in soil, as well as the growth and water consumption of the maize, the most suitable irrigation method for maize in the saline soil is alternating saline water and freshwater(T3).

Keywords

• alternating irrigation
• shallow groundwater
• water-salt distribution
• water use efficiency