Effects of irrigation amount and frequency on soil water and salt dynamics and water use efficiency of mulched drip-irrigated cotton in Southern Xinjiang

NING Huifeng; CAO Zhenxi; LI Songmin; SHI Lujian; SHEN Xiaojun; LI Yong; HAN Qisheng; ZHANG Xianbo; YANG Guang

doi:10.13522/j.cnki.ggps.2023522

Abstract：[Objective]Cotton is a major economic crop in saline-alkali regions of southern Xinjiang,where soil salinity and water availability affect crop growth and yield.Optimizing irrigation is essential for improving water use efficiency(WUE)and maintaining stable production of cotton in these regions.This paper experimentally studies suitable drip-irrigation strategies for cotton cultivated in saline-alkali soil with plastic film mulch.[Method]A field experiment was conducted from April to August 2018 to evaluate the influence of plant row spacing and irrigation methods on cotton growth.There were four irrigation-amount treatments by irrigating 45,37.5,30 mm and 22.5 mm of water in each irrigation;the irrigation interval was 10 and 7 days.In the experiment,we measured soil water and salt content in the root zone,growth and WUE of the cotton.[Result]During the first 70 days after sowing,water content in the 0-40 cm soil layer decreased with decreasing irrigation amount.At the seedling stage,soil moisture difference between wide and narrow plant row spacing was negligible,while by the bud stage,water content difference in soil below 40 cm between different row spacings became increasingly pronounced.Soil salt content in the top 0-40 cm soil layer showed minimal variation among treatments during the seedling stage,but significant differences emerged after flowering began.Salt content in the 60-100 cm soil layer steadily declined in the first 80 days post-sowing and then stabilized thereafter.Irrigation 45 mm every 10 days during the bud stage followed by 30 mm every 7 days during the flowering stage achieved the highest WUE of 1.42 kg/m3,with a seed cotton yield of(6 916.2±338.6)kg/hm2.Irrigating 45 mm every 10 days during the bud stage and 37.5 mm every 7 days during the flowering stage yielded the highest seed cotton production of(7 703.9±641.9)kg/hm2,with a WUE of 1.37 kg/m3.[Conclusion]For cotton cultivated with drip irrigation under plastic film mulch in saline-alkali soils,the optimal irrigation strategy is irrigating 45 mm every 10 days during the bud stage followed by 37.5 mm every 7 days during the flowering stage.This can effectively balance soil moisture and salinity dynamics,while maximizing water use efficiency and seed cotton yield.