Reducing nitrate (N) leaching is important for reducing pollution sources to groundwater worldwide. For the annual double cropping system of winter wheat and summer maize in the North China Plain (NCP), irrigation management in the dry winter wheat growing season affects the water balance in the summer rainy maize growing season and therefore influences the water drainage and N leaching from the crop root zone. Measurement data from a field experiment with three irrigation schedules for winter wheat and maize from 2006 to 2009 were used to calibrate and validate the APSIM model (Agricultural Production Systems sIMulator). The evaluated model was used to simulate the long-term effects of different irrigation schedules for the winter wheat season on N leaching during the summer maize season from 1981 to 2018, and to investigate strategies with minimum irrigation to maintain crop yield while reducing N leaching. Simulation results showed that when irrigation application to winter wheat was less than twice (total irrigation amount being less than 140 mm during the growing season), soil water depletion by winter wheat was greater than 130 mm for the top 2 m soil profile, which led to a significant reduction in drainage and N leaching during the summer rainy season. The average drainage during the summer maize season varied from 1 mm up to 134 mm following rainfed to five irrigations during the winter wheat season. The average N leaching corresponding to the drainage changes varied from 0.6 kg/ha to 67.1 kg/ha. The results indicated that the reduction in irrigation water use during the dry season significantly increased soil water use, allowing more rainfall to be stored in the root zone soil profile without being leached during the rainy season. Although the reduction in irrigation water use reduced the yield of winter wheat, using moderate irrigation scheduling (one or two irrigations) significantly improved water use efficiency for grain yield with only a small yield penalty. Therefore, reducing the N leaching potential by increasing soil water use through irrigation management is an effective measure in the NCP.

减少硝酸盐（N）的淋洗对于减少全世界地下水的污染源非常重要。对于华北平原冬小麦和夏玉米的年度双季种植系统，冬小麦干燥季节的灌溉管理会影响夏季多雨玉米生长季节的水分平衡，从而影响排水和氮素淋失。从作物根部区域开始。使用2006年至2009年的冬小麦和玉米三个灌溉计划的田间试验的测量数据来校准和验证APSIM模型（Agricultural Production Systems sIMulator）。该评估模型用于模拟1981年至2018年夏季玉米季节不同灌溉计划对夏季玉米氮素淋溶的长期影响，并研究最少灌溉的策略，以维持作物产量同时减少氮的淋失。模拟结果表明，当冬小麦灌溉量少于两次（生长季节总灌溉量小于140 mm）时，在前2 m的土壤剖面上，冬小麦的土壤耗水量大于130 mm，这导致大大减少了夏季雨季的排水和氮淋失。夏季玉米季节的平均排水量从雨养后的1毫米到134毫米不等，而冬小麦季节则为五次灌溉。对应于排水变化的平均氮淋失量从0.6千克/公顷到67.1千克/公顷不等。结果表明，旱季灌溉用水量的减少显着增加了土壤用水量，可以将更多的降雨存储在根区土壤剖面中，而在雨季期间不会被淋洗。尽管减少灌溉用水减少了冬小麦的产量，但采用适度的灌溉计划（一两次灌溉）可显着提高谷物产量的水分利用效率，而收成损失却很小。因此，通过灌溉管理增加土壤水的使用量来减少氮的淋溶潜力是NCP的一项有效措施。