摘要:本文总结了中国科学院遗传与发育生物学研究所农业资源研究中心围绕华北典型地区冬小麦-夏玉米一年两熟开展的节水灌溉研究。在位于华北中北部的中国科学院栾城农业生态系统试验站的定点试验结果显示，从1980年到2017年，在充分灌溉条件下冬小麦产量增加55.7%、夏玉米产量增加59.7%。冬小麦生育期耗水（ET）从400 mm增加到465 mm；玉米耗水年平均稳定在375 mm左右；年耗水量从777.0 mm增加到834.4 mm；满足冬小麦、夏玉米生育期耗水条件下，年灌溉需水量平均300 mm，必须减少灌溉用水和田间耗水，才能解决区域地下水超采问题。研究发现在限水灌溉条件下，冬小麦拔节期1次灌溉可显著促进作物营养生长和根系生长，利于后期土壤水分高效利用，在维持作物稳产基础上，比充分灌溉年节水165.2 mm。研究发现进一步利用小定额灌溉技术，通过增加灌水频率、缩减次灌水量，可增加有限水对作物的有效性，实现作物根系、土壤水分和养分在空间上的耦合，进一步提升有限灌溉对作物的增产作用。只考虑维持播种时良好土壤水分条件、生育期不进行灌溉的最小灌溉模式，与充分灌溉模式相比，产量减少28%，但可节约灌溉水69%，田间耗水减少43%，水分利用效率提高13%，年耗水量维持在560 mm左右。相对于减熟制节约灌溉水措施，冬小麦-夏玉米一年两季最小灌溉模式总产量高于两年3作5.5%～12.0%，年耗水量低于两年3作10%～13%，可显著消减减熟制带来的休闲期土壤蒸发损失。因此，实施冬小麦、夏玉米生育期节水灌溉，如最小灌溉、关键期灌溉，可大幅度降低灌水量和作物生育期耗水量，同时又能维持一定的生产能力，是华北实施地下水限采措施下应优先考虑的技术选择。
Abstract:This paper summarized the researches of Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences on water-saving irrigation for winter wheat and summer maize at the Luancheng Agro-Ecosystem Experimental Station, Chinese Academy of Sciences, a typical farming area in the North China Plain (NCP). The results from long-term field studies showed that for the period from 1980 to 2017, yield of winter wheat was increased by 55.7% and that of summer maize by 59.7% under fully irrigated conditions. Water consumption (ET) of winter wheat was increased from 400 mm to 465 mm, ET of summer maize was relative stable at about 375 mm. Annual ET was increased from 777.0 mm in the 1980s to 834.4 mm in the 2010s. The annual irrigation water demand was averagely around 300 mm. Therefore, it was necessary to reduce irrigation water use to conserve local groundwater resources. Under limited irrigation, one irrigation of winter wheat at jointing stage significantly increased vegetative and root growth of this crop, which was beneficial for the efficient use of soil water at later stages of crop growth. Under this critical stage irrigation schedule, annual ET was reduced by 165.2 mm, while grain production remained stable at relative higher level. Results also showed that by reducing irrigation amount per application and increasing irrigation frequency under limited irrigation, the combined effects of interaction of crop root, soil water and soil nutrient at the topsoil layer could increase water availability to the crop and thereby increase grain production and water use efficiency. A minimum irrigation (MI) schedule was developed for more serious water shortage regions, which was to maintain good soil moisture conditions at the time of sowing and no other irrigation being applied during the other growth periods. As compared with full irrigation, yield was reduced by 28%, but irrigation water use was reduced up to 69%, reduction in ET was by 43% and water use efficiency increased by 13%. Annual ET was reduced to 560 mm and annual irrigation water use was reduced to 120 mm. Significant reduction in irrigation water use was achieved as compared with the full irrigation schedule. As compared with the reduction in cropping intensity (RCI) measure (changing annual double cropping of winter wheat and summer maize to three crops every two years), MI schedule could fully use the rainfall resources and reduce soil evaporation consumption during fallow period under RCI. Yield of winter wheat and summer maize for MI under double cropping system was 5.5%-12.0% higher than that for RCI, with annual ET of 10%-13% less. Based on results from the long-term field experiment, the implementation of water-saving irrigation schedule such as MI and critical irrigation scheduling significantly reduced irrigation water use and at the same time maintained stable grain production. Therefore, water-saving irrigation schedule under double cropping of winter wheat and summer maize was recommended as one of the important measures for solving the problem in groundwater overdraft in the NCP.
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