河北省低平原地区主要作物农田水分盈亏分析

AN ANALYSIS OF FIELD-WATER BUDGET OF THE MAIN CROPS ON THE LOW PLAIN IN HEBEI PROVINCE

本文计算了河北省低平原地区主要农作物的需水量,根据农田水量平衡方程估算了冬小麦、夏玉米和棉花整个生长期的水分盈亏及其在地区上的差异,分析了作物需水关键期的水分状况。

According to the observed data of water consumption (E) of the main crops in the prefectures of Shijiazhuang, Xinxiang and Dezhou and in Beijing, evapotranspiration coeffcient of crops (a) in Penman’s formula is determined by calculating evaporativity from the water surface (E0) : a = 0.78 for winter wheat, a = 0.72 for cotton and a = 0.78 for corn. A formula, E = aE0, is adopted to estimate water consumption of the crops in their growing pa-riod in the low plain of Hebei province. The estimated water consumption is as follows ; 400-470 nim for wheat ;613-708 mm for cotton and 350-405 mm for corn.In successive rotation of wheat and corn, an annual amount of water deficit in wheat field is about 242 mm, while in monoculturellt, It is reduced approximately to 164 mm. water deficit for one-crop farming of cotton and corn amounts to 107 mm and 39 mm respectively.water deficit for winter wheat in Cangzhou and the eastern part of Lang-fang exceeds 180 mm, while it is decreased to less than 140 mm in Handan and southern Xingtai. The areas seriously suffered from water shortage are located in southern Changzhou and the western part of Xintai and Hengshui. As for the areas of Wenan Dacheng and Qingxian Counties, water deficit becomes less serious.From April to May is a period of the highest water consumption of wheat and the sowing time of cotton and other spring sowing crops. But in this period precipitation is the lowest. Therefore, a complementary amount of water is required in irrigation.