半干旱黄土高原集水农业的气候学基础

Climate basis of rainwater-harvesting agriculture in the semiarid Loess Plateau of China

水分不足是半干旱黄土高原旱地农业农田生产力水平的主要制约因素通过对甘肃黄土高原半干旱区自然降水和土壤水分等农业气候因子的动态分析，发现5，6月间降水低谷与7～9月丰水季节交替重复出现是本区正常的天气现象．这一降水低谷引起土壤水份低值槽现象，造成夏粮作物的“卡脖旱”，严重影响产量在该区发展集水农业，雨季蓄积雨水，于次年5～6月间干旱季节进行补偿性灌溉，充分利用两季雨水，消除土壤水份低值槽现象，从而达到增产目的。因此，从气候学角度讲。

Insuffcient water is the main factor that limits the field productivity of dryland in semiarid Loess Plateau. By means of analysis on the natural precipitation and soil water, the authors suggest that it is a normal climate phenomenon that the precipitation trough(extremely low value) in May-June altermating with the peak value from June to September. This precipitation tough leads to the low value of soil water, which usually results in the critical drough of the summer crops, and reduces the yield. harvesting rainfalls in raining season and irrigating in the next May-June, can raise the use efficiency of rainwater as well as reduce the soil water deficit, thus increases the yield. Therefore based on the climatic theory, to develop rainwater-harvesting agriculture is necessary and feasible in the semiarid Loess Plateau of China.