Study On Water Consumption Law And Irrigation Schedule Optimization Of Cotton Under Mulch Drip Irrigation In Kashgar River Irrigation Area In Southern Xinjiang

Object:The Kashgar River Basin is located in the west of Tarim Basin in Xinjiang Uygur Autonomous Region of China.Most of the water resources in the basin are supplied for agricultural irrigation.However,due to the lack of local suitable irrigation systems,water use efficiency is low.The existing studies are mostly concentrated in the northern Xinjiang or Tarim River basin,and there are few studies on the irrigation system of the Kashgar River basin in the southern Xinjiang.For this reason,this study explored the water demand law of cotton growth period under different mulch drip irrigation systems in the irrigation area of the Kashgar River basin through two consecutive years of field fixed-point observation and experiment,clarified the multi-dimensional information response characteristics of soil moisture,cotton yield,quality,etc.,and constructed the cotton mulch drip irrigation system suitable for the region through model simulation.This study can provide theoretical basis for the determination of scientific and reasonable irrigation mode and irrigation system for cotton in the irrigation area of the Kashgar River Basin,and provide technical support for the rational use of existing water resources in the irrigation area and the improvement of local water resource utilizationMethods:In this study,the experiment of drip irrigation under cotton mulch was carried out at Buhala Water Pipe Station(Kashgar City,Kashi County)in the Kashgar River Basin from 2021-2023 for two consecutive years.Different lower limits of irrigation soil moisture content were set at different stages of the growth period,Reduced irrigation(100%,90%and 80%)and reduced irrigation(90%and 80%)were set up in the whole growth period and in the bud stage,flower and boll stage and boll opening stage,and furrow irrigation treatment was added,with a total of 10 treatments.The soil moisture change during the whole growth period of cotton is continuously and dynamically monitored by using the intelligent moisture and Trime,and the farmland evapotranspiration,water consumption characteristics of cotton in different growth periods,cotton yield,quality and water use efficiency are calculated.The root zone water quality model(RZWQM2)will be calibrated and calibrated through the field measurement results,and the cotton yield and evapotranspiration under different application scenarios will be simulated and predicted,Combined with field experiment and model simulation,the water consumption law and suitable irrigation schedule of cotton under mulch drip irrigation in Kashgar River irrigation area were obtained.Results:(1)Compared with furrow irrigation,drip irrigation can effectively reduce the evapotranspiration by10.86%-70.86%.In the whole growth period,the evapotranspiration and crop coefficient of cotton under drip irrigation treatment show a trend of first increasing and then decreasing.Deficiency irrigation at the bud stage,flowering and boll stage and boll opening stage is conducted according to 90%field capacity,which has the best effect on reducing crop coefficient.Deficiency irrigation at the bud stage or boll opening stage has no significant impact on crop coefficient.Not sufficient irrigation at 80%throughout the entire growth period is not conducive to reducing soil conductivity.(2)Compared with furrow irrigation,the lint percentage of drip irrigation increased by 3.30%-6.61%at the same 100%irrigation,and the seed index of 80%irrigation treatment at the bud stage and boll opening stage increased by 0.31%-14.14%compared with other treatments.The yield of 90%irrigation treatment in the whole growth period was 7.93%-10.18%higher than that of 90%irrigation treatment only in the boll opening period.Only reducing irrigation at the boll opening stage can maintain a high cotton boll weight;80%irrigation during the whole growth period is conducive to the improvement of cotton quality.(3)The calculation results of the model indicate that the highest and low yields appear in the scenarios of130%incremental irrigation group and 70%reduced irrigation group respectively.Through comparison of different hydrological year quotas,it was found that the experimental irrigation quota per mu decreased by72.31 m~3-32.74 m~3.Based on the RZWQM2 model,the optimal irrigation water volume for full irrigation and 10%and 20%water saving under the premise of ensuring the yield is 290.28mm,229.81mm and213.24mm respectively.Conclusion:Under 100%irrigation condition,drip irrigation ditch irrigation can reduce 10.86%-70.86%evapotranspiration and increase 3.30%-6.61%cotton lint percentage in the whole growth period.The cotton evapotranspiration and crop coefficient under drip irrigation treatment show a trend of first increasing and then decreasing.At the flowering and boll stage,full irrigation is conducive to soil salt leaching,and the soil conductivity of 80%irrigation treatment at the bud stage and boll opening stage remains at a low level.Compared with other treatments,the yield of 90%irrigation treatment increased by 4.67%-15.78%,and the irrigation amount decreased by 12.16%-27.75%.Based on the RZWQM2 model,the irrigation water volume for full irrigation and 10%and 20%water saving under the premise of ensuring the yield is 290.28mm,229.81mm and 213.24mm respectively.