运用土壤水盐运移模型优化棉花微咸水膜下滴灌制度

Optimization of mulched drip-irrigation with brackish water for cotton using soil-water-salt numerical simulation

为优化设计棉花微咸水膜下滴灌灌溉制度,利用HYDRUS建立含根系吸水项的土壤水盐运移数值模拟模型,并用田间试验资料进行参数识别和模型验证。用验证认可的数值模型优化设计棉花微咸水膜下滴灌和非生育期洗盐灌溉制度,并预测棉花生育期水盐运移规律和长期效应。结果表明:模型仿真度较高、运行速度较快;T检验说明土壤含水率和电导率模拟值与实测值均无显著差异;模型参数中形状系数α、n对含水率影响较大,纵向弥散度DL对电导率影响较大;当地膜下滴灌适合生育期一膜双管、低额高频灌溉,并结合非生育期1年1次或2年1次大水漫灌洗盐,20a的模拟结果显示此灌溉制度下不会引起土壤次生盐渍化。

In order to optimize the program of mulched drip-irrigation with brackish water for cotton,a soil water and salt numerical model with the root water uptake item was built by using HYDRUS.The parameters were identified and model was verified using the data of field experiments.The verified model was used to set up proper irrigation program of mulched drip-irrigation at cotton growth season and the flood irrigation at non-growth season for leaching soil salt,and to predict soil water and salt migration characteristics and its long-term effect.The results showed that the simulation matched observation well and the calculation rate was fast.The simulated and observed soil water and salt had no significant difference by T test.The parameters α and n had more notable influences on soil water than other parameters,while the longitudinal dispersivity D L had notable influence on soil salt.The proper program of mulched drip-irrigation in the study area is that two pipes are set up for one tarp with low irrigation water quantity and high irrigation interval combined with once flood irrigation during non-growth season for one or two years.Twenty-year simulation showed that the irrigation program would not result in soil secondary salinization.