Influence of mulched drip irrigation amount on yield and water use efficiency of cotton in regions with shallow saline groundwater

【Objective】 Cotton production in Xinjiang relies on irrigation. However, in regions with shallow saline groundwater, managing irrigation to avoid soil salinity is crucial to sustaining cotton growth. The purpose of this paper is to elucidate the influence of mulched drip irrigation amount on cotton yield and water use efficiency of irrigation water in regions characterized by shallow saline groundwater. 【Method】 The experiment was conducted from April 2022 to October 2023. It compared four irrigation amounts: 300 mm(W1), 375 mm(W2), 450 mm(W3) and 525 mm(W4). In each treatment, we measured spatiotemporal changes in soil water and soil salt content, groundwater table and ground salinity, as well as growth, yield and water-use efficiency of the cotton. 【Result】 ① Soil desalination rate increased with irrigation amount. In the W4 treatment, the total soil desalination rate in the 60 cm soil layer varied from 29.78% to 58.19%. ② Increasing irrigation amount increased groundwater recharge, but reduced groundwater salinity from 6 g/L to 4-5 g/L, benefiting groundwater utilization by the crop. ③ With the increase in irrigation amount, plant height, leaf area index, dry matter accumulation and yield of the cotton increased first followed by a decline. The growth index of cotton under W3 treatment was the best, with a potential yield of 7 127.66 kg/hm2. Water use efficiency decreased with the increase in irrigation amount. 【Conclusion】 The optimal irrigation schedule for cotton under mulched drip irrigation in the studied area is 450 mm. Although its associated water use efficiency is not the highest, it improves ecological environment, meets ecological water consumption and safeguards crop growth.