干旱区膜下滴灌棉田灌溉制度及土壤水盐运移规律研究

以棉花各生育期适宜土壤含水率上、下限差值为灌水控制指标,设置3水平灌水处理,开展膜下滴灌大田试验,分析研究适宜试验区棉花生长、水分利用效率高的灌溉制度及膜下滴灌棉田土壤水盐运移规律。结果表明:适宜土壤含水率上、下限差值形成的灌溉制度,决定了土壤水盐运移规律、盐分分布和积累特征。总体表现为:空间上土壤水分分布与滴灌带间距呈负相关系,盐分分布则相反,0~40 cm深度土壤水分在灌后重分布,盐分在滴灌水分的淋洗作用下定向运移,至湿润体边缘积聚。综合分析关键点与主根层的土壤水盐时间序列变化,T2处理(385 mm/18次)主根层0~40 cm深度水分处于棉花生长的适宜含水率范围,并形成淡化脱盐区,对盐分的调控最佳。T2处理棉田产量最高,为6 083 kg/hm~2,水分利用效率为1.05 kg/(mm·hm~2),为适宜的灌溉制度。

Study on Irrigation Scheduling and Soil Water-salt Transport Law under Mulched Drip-irrigation in Arid Area

Based on the upper and lower limit of appropriate soil moisture content at each growth stage of cotton, with the difference value of appropriate soil moisture content as irrigation control index, 3 different irrigation level treatments was set up to carry out cotton field trials under drip-irrigation.The soil water-salt transport law and irrigation scheduling appropriate for local cotton growth and high WUE under mulched drip-irrigation was studied, and the yield-increasing effect was evaluated.The experimental results show that the irrigation scheduling obtained from difference of appropriate soil moisture content determines soil water-salt transport law, distribution and accumulation characteristics.The overall performance is that the soil water distribution and drip irrigation belt distance is negatively correlated;soil salt and water distribution has opposite relationship, the soil water redistributes after irrigation, salinity directionally moves under the irrigation leaching to accumulate in the edge of the wetting front.Through comprehensive analysis of the soil water and salt changes in time series of the key point and main rot layer, it is found that the soil moisture of main root layer of 0~40 cm depth of T2 (385 mm/18 times) treatment is in the appropriate moisture content range for cotton growing, the desalination zone is formed, and the salt-control effect is the best;different irrigation scheduling has certain influence on cotton yield, the T2 treatment can obtain highest cotton yield of 6 083 kg/hm 2 and WUE of 1.05 kg/(mm·hm 2), so it is the appropriate irrigation scheduling.