２年的大田试验研究表明，在黄土高原半干旱区，春小麦农田有限灌溉的关键时期为３叶期到孕穗期之间，但由于该地区降水变率很高，不同降水年型有限灌溉的关键时期和增产效果有很大差异，实际的需水关键期和作物生理的需水关键期往往不相吻合．对半干旱地区的有限灌溉对策及作物的耗水过程和产量形成过程进行了讨论． Two years of field experiments show that in the semi-arid region of the Loess Plateau, the critical period for limited irrigation of spring wheat farmland is between the three-leaf stage and the booting stage. However, due to the high precipitation variability in this area, the key to limited irrigation of different precipitation years Period and production efficiency are very different, the actual critical period of water demand and crop physiology critical period of water often do not match. The limited irrigation measures in semi-arid areas and the process of water consumption and yield formation of crops are discussed.