地下地膜截水墙——一种新的节水农业技术

UNDERGROUND PLASTIC SHEET WALL A New Water_Saving Agricultural Technique

简要分析了西北黄土梯地和四川紫色土旱坡地土壤水侧向运移的特点，介绍了地下地膜截水墙阻断土壤水分侧向运移、保持耕地土壤水分、抗旱增产的基本原理和建设技术。陕北米脂黄土梯田的试验结果表明，该技术可以有效地减少梯田梯坎蒸发，增产效益显著（５７７％～８８６％）。该技术也非常合适解决四川丘陵区紫色土旱地季节性干旱问题。

An underground platic wall,which is vertically set up across a field to interrupt lateral movement of soil moisture,is able to reduce soil moisture losses and to prevent droughts in nonirrigated field. In the semiarid Loess Plateau,annual precipitation ranges between 400 mm～600 mm and 50 %～70% of it loses by ground evaporation in non_irrigated field. Soil moisture laterally moves from the terrace field to the terrace banks mostly as capillary water because of severe evaporation on the banks.For a terrace with width of 5 m and bank height of 2.7 m,at least 50% of the soil moisture losses by ground evaporation occur on the banks.An underground plastic sheet wall is set up nearby the downslope bank and at the toe of the upslope bank to interrupt lateral movenent of soil moisture from the field to the banks.An experiment in a terrace field in Mizhi,Shaanxi Province,in 1998, shaw that potato production in the trail plots with underground plastic sheet walls of 0.5 m～1.5m in depth was 57.7 %～88.6 % higher than that in the trail plot without the walls. In the humid Sichuan Hilly Basin where annual precipitation is about 1000 mm,soil moisture laterally moves downslope mostly as throughflow on sloping cultivated land. For a sloping field with a slope of 5°,thoughflow explains about 12% of the precipitation.An underground sheet wall is set up across slope in a sloping field,should reaches the inpermeable layer.The wall can interrupt throughflow to build up a micro_underground reservoir.This technique is effective to prevent seasonal droughts and can intercept 50% of the throughflow and increase crop production by 0.6～0.75 t/hm 2 in non_irrigated field at least.