华北平原灌溉农田的土壤水量平衡和水分利用效率

华北平原农业面临的主要问题是水资源短缺,地下水位持续下降。通过一维土壤水量平衡模型模拟了华北平原不同灌溉方式下农田耗水量和土壤水分深层渗漏的变化,并分析了作物的产量和水分利用效率。结果显示在正常的灌溉条件下,冬小麦季地下水的采补差额超过了200mm,某生育期一定程度的水分亏缺(返青期、拔节期或灌浆期)能明显减少冬小麦的耗水量,但没有明显减少作物的产量。因此,在一定程度上减少灌溉是可行的,但仍不能达到地下水资源的采补平衡。从长远来看,华北平原维持可持续的地下水灌溉开采,应减少冬小麦的种植面积、增加低耗水经济作物的比例。

Soil-Water Balance and Water Use Efficiency on Irrigated Farmland in the North China Plain

Water resource shortage is becoming a major problem in the North China Plain, especially in groundwater resource because groundwater table is persistently declining. A Soil-Water-Balance approach was used to simulate crop evapotranspiration (ET) and soil water recharge (D) at Luancheng Agro-ecosystem Stationin the North China Plain, and grain yield (GY) and water use efficiency (WUE) for wheat (Triticum aestivum L.) and maize (Zea mays L.) were investigated under different irrigation schedules. Results indicate that ground-water mining of about 200 mm/a from the rapidly depleting aquifer system supplies the deficit under normal soil water condition in winter wheat season. Reversing ground-water declines due to irrigation will mean either reducing the irrigated area, reducing grain yields, or both, which suggests that it is suitable to reduce wheat-cropped areas. Although severe SWD decreases both ET and GY of wheat and maize, slight SWD for winter wheat during a stage from green turn to grain-filling stage did not evidently reduce GY. SWD, severe or slight, all significantly reduced ET, which mainly depended on the different irrigation amounts. Thus, it is possible to reduce ET somewhat instead of reducing GY. In a long way, in order to keep sustainable ground-water mining, the cropped area of winter wheat needs to decrease, while it is very crucial to increase the area of economic crops with low water consumption.