农田水盐运移与作物生长对亏水滴灌的响应和模拟研究

Response and Simulation of Farmland Water-Salt Transport and Growth of Crops to Deficit Drip Irrigation

为探究西北干旱地区农田水盐运移与作物生长对亏水滴灌的响应以及层状土壤中水分溶质运移和作物生长耦合模型(Layered soil water-solute transport and crop growth model,LAWSTAC)的适用性,设置3种水分处理W100、W70、W40,分别表示灌溉需水量的100%、70%和40%,于2018年在农业农村部作物高效用水武威科学观测实验站进行了大田试验。结果表明:在制种玉米生长苗期,单次灌水后,浅层(0~20 cm)土壤含盐量降低;经全生育期灌溉后,灌水量越大,浅层脱盐和深层积盐现象越明显。3种水分处理下灌水量越多的处理,制种玉米叶面积指数(LAI)和最终地上生物量越高,作物长势越好。LAWSTAC模型能较好地模拟农田水盐运移和制种玉米的生长过程;各处理LAI模拟值与实测值之间的决定系数R^2均为0.99,RMSE为0.20~0.87 cm^2/cm^2;各处理地上生物量的模拟值与实测值的R^2均为0.99,RMSE为1.62~3.57 t/hm^2,说明LAWSTAC模型可以较为准确地模拟制种玉米LAI、地上生物量的动态变化。0~80 cm土层贮水量的模拟结果表明,各处理R^2为0.41~0.61,RMSE为12~21 mm;0~80 cm土壤盐分质量浓度的模拟结果表明,各处理R^2为0.53~0.60,RMSE为1.37~2.56 g/L,效果较好。因此,LAWSTAC模型可为当地复杂土壤条件的农田进行生产力的初步预测与评估。

The research was based on a developed model for farmland watersalt transport and crop growth(LAWSTAC).In order to explore the response of farmland water and salt transport and crop growth to deficient drip irrigation and test the applicability of LAWSTAC model in the northwest arid region,field experiment was carried out in the Wuwei Experimental Station for Efficient Water Use in Agriculture,Ministry of Agriculture and Rural Affairs in 2018.Three treatments were considered in the experiment,including three irrigation levels,i.e.,100%,70%and 40%of full irrigation(i.e.,W100,W70 and W40),respectively.The results showed that salinity in shallow(0~20 cm)soils was reduced after the irrigation during the seedling period of seed-maize production.For the whole growth period,the greater the irrigation amount was,the more obvious the phenomenon of desalination in upper layer and salt accumulation in deeper layer was.Larger irrigation generally resulted in higher plant leaf area index(LAI)and higher final above-ground biomass of the seed-maize under the three irrigation levels.The LAWSTAC model can well simulate the farmland watersalt transport and the growth of seed-maize.The values of determination coefficient(R^2)of the simulated and measured LAI were 0.99,and the values of root mean square error(RMSE)were between 0.20 cm^2/cm^2 and 0.87 cm^2/cm^2.The values of R^2 of the simulated and measured aboveground biomass were 0.99,and the values of RMSE were between 1.62 t/hm^2 and 3.57 t/hm^2.It was demonstrated that the LAWSTAC model can accurately simulate the dynamic changes of LAI and aboveground biomass of seed-maize.LAWSTAC model was validated for simulating soil water storage in 0~80 cm soil layer under different treatments with 0.41<R^2<0.61 and 12 mm<RMSE<21 mm respectively.Under all treatments,the soil water salinity of 0~80 cm soil depth was simulated well with 0.53<R^2<0.60 and 1.37 g/L<RMSE<2.56 g/L.Therefore,the LAWSTAC model can be used for the preliminary prediction and evaluation of the productivity of farmland with complex soil conditions.