Crop coefficient and water-use efficiency of winter wheat/spring maize strip intercropping

Winter wheat and spring maize strip intercropping system is widely practiced in northern China. In this study, a field experiment with typical winter wheat and spring maize strip intercropping systems was carried out in 2003-2004 and 2004-2005 seasons to investigate crop coefficient (K-c, defined as the ratio of actual crop evapotranspiration to reference crop evapotranspiration) and water-use efficiency (WUE, defined as the ratio of grain yield to total actual evapotranspiration) of intercropping systems in the Huang-Huai-Hai Plain of China. Crop coefficient values of sole winter wheat varied in ranges of 0.26-0.36, 1.09-1.15 and 0.27-0.41 at initial, mid and late season in two seasons, respectively. K-c values of sole spring maize varied in 0.36-0.37, 1.18-1.19 and 0.22-0.28 at initial, mid and late season in two seasons, respectively. K-c values of winter wheat/spring maize intercropping system varied in 0.31-0.35, 1.14-1.23 at initial and middle wheat growing season, in 0.65-0.70 at wheat-maize co-growing period, and in 1.24-1.25 and 0.21-0.27 at middle and late maize growing season in two seasons, respectively. Compared to yields of spring maize and winter wheat in monoculture, total grain yield (wheat + maize) of winter wheat/spring maize intercropping system increased by 39% and 98%, respectively. Average WUE in the intercropping system was 21.72 kg ha(-1) mm(-1), which was 23% less than that of the sole maize, but 4% greater than that of the sole wheat (4%). Therefore, although winter wheat/spring maize intercropping system does not improve WUE, it may significantly raise yield, which is helpful to ensure food safety in northern China. (c) 2008 Elsevier B.V. All rights reserved.