Effect of soil water deficit on evapotranspiration crop yield.pdf

Agricultural Water Management 64 (2004) 107–122 Effect of soil water deficit on evapotranspiration, crop yield, and water use efficiency in the North China Plain Yongqiang Zhang a,b,? , Eloise Kendy c,1 , Yu Qiang a , Liu Changming a , Shen Yanjun d , Sun Hongyong b,2 a Hydrology and Water Resources Branch, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Building 917, Datun Road, Anwai, Beijing 100101, PR China b Shijiazhang Institute of Agricultural Modernization, CAS, 286 Huaizhong Road, Shijiazhuang 050021, PR China c Department of Biological and Environmental Engineering, Cornell University, Riley Robb Hall, Ithaca, NY 14853, USA d Graduate School of Science and Technology, Chiba University, 1-33 Yayoi, Inage, Chiba 263-8522, Japan Accepted 11 June 2003 Abstract In the North China Plain (NCP), excessive groundwater pumping is a serious problem. In this study, different groundwater irrigation schedules were applied. A simple soil water balance approach was introduced to evaluate crop evapotranspiration (ET) and water use efficiency (WUE). Under normal irrigation scheduling, groundwater mining occurs at a rate of over 200 mm per year from a rapidly depleting aquifer system. Severe soil water deficit (SWD) decreases grain yield (GY) of wheat (Triticum aestivum L.) and maize (Zea mays L.), while slight SWD in a growth stage from spring green up to grain-filling winter wheat did not evidently reduce GY and WUE. A se- vere or slight SWD significantly reduces ET, which mainly depends on irrigation amounts. Thus, it is possible to reduce ET somewhat without significantly decreasing GY. ET was correlated to GY in a parabolic function, and maximum yield for winter wheat occurred when optimal ET for win- ter wheat was about 447 mm. It was important for wheat and maize to be irrigated before sowing ? Corresponding author. Tel.: +86-10 fax: +86-10 E-mail addresses: zhangyq@igsnrr.ac.cn (Y. Zhang), ek65@cornell