Water-saving effect under adjustment of cropping systems and optimization of water and nitrogen in high yield regions of North China

Abstract: Winter wheat-summer maize double cropping is an important rotation system mainly practiced in the North China Plain. Crop yield and water use efficiency in this rotation system are influenced by rainfalls. Winter wheat yield was restricted by limited precipitation and irrigation in spring. To study water-saving rotation system and measures, a 2-year field experiment was conducted in the high yield regions of the North China Plain by adjusting cropping systems and optimizing water and nitrogen management strategies. Six rotation cropping systems, including convention (Con), optimum (Opt), No-Tillage (No-T), water saving I (WS I), water saving II (WS II) and water restoration (WR), were designed to investigate the crop yield, crop water consumption and irrigation water-use efficiency. The Con treatment as CK was a double cropping system of winter wheat interplanted with summer maize, which was conducted with conventional agricultural practice. Both Opt and No-T treatments were the double cropping system of winter wheat rotated with summer maize, and conducted with water and nitrogen optimization measures. WS I and WS II treatments were the three-crops in two years system, and combined with water and nitrogen optimization measures. The former was winter wheat-summer maize-spring maize rotation and the latter was winter wheat-summer soybean-spring maize rotation. The WR treatment was one crop (spring maize) in a year system and was also conducted with water and nitrogen optimization measures. Compared with the double cropping system of winter wheat interplanted with summer maize, the system of winter wheat rotated with summer maize by water and nitrogen optimization, the results presented a high level of production and low level of crop water consumption with the irrigation water-use efficiency improved by 52%-54%. Compared with the double cropping system, either the three crops in two years system or the one crop in a year system, significantly decreased crop water consumption, improved the irrigation water-use efficiency by 58%-172% and decreased the production by 16%-27%. In conclusion, it is feasible to change the winter wheat / summer maize double cropping system into winter wheat rotated with summer maize system under water and nitrogen optimization strategies in the North China Plain. Considering the fact of severe water shortages in this region, the three-crops in two years system may be a useful mode of planting to obtain the highest possible crop yield.