| During two consecutive years (1998-1999) a field experiment was conducted in Minqin, Gansu province, NW China. The main objective of this study was to determine irrigation principle and techniques with water saving and efficiency for intercropping, especially for spring wheat / corn intercropping under arid conditions. The main results achieved as follows.(1) Intercropping is the most potential for increasing grain yield in arid regions. In this study, a new irrigation method for intercropping, Divided Crop Irrigation (DCI), has been presented based on the features of the spatial variability in intercropping fields, that is one crop alternating with another crop, and the principles of precision irrigation. Furthermore, a divided crop drip irrigation (DCDI) method for intercropping has been developed through applying drip irrigation to the DCI.(2) The remarkable characteristics of the DCDI is high water use efficiency and great effect of water saving. The results showed that the grain yield of the component of spring wheat in the intercropping came up to 7000 - 7600 kg/ha, the WUE reached 1.2 - 1.6 kg/m3, and the grain yield of the corn component was 6000 - 9080 kg/ha, the WUE 1.0-1.7 kg/m3, under the condition of DCDI for the intercropping in the arid region. Meanwhile, there was a 48% to 61% reduction of irrigation water in the DCDI for the intercropping as compared with surface irrigation method.(3) In this study, soil evaporation between the crop rows and the dynamic processes in the spring wheat / corn intercropping field under the conditions of DCDI was measured by using mico-lysimeter. Therefore, the data of soil evaporation and the proportions between soil evaporation and transpiration for the two crops have been obtained. The results showed that, under the condition of high grain yield, the soil evaporation between the rows of spring wheat in a growing season was 1080 to 1380 m3/ha and the soil evaporation of corn was 2430 to 2730 m3/ha,...
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