关键词: 稻油轮作, 氮肥运筹, 作物产量, 系统能值产量, 氮素积累量, 氮肥利用率, 氮素表观平衡

Abstract:

【Objective】The rice-rapeseed rotation is a typical paddy-upland rotation cropping pattern in the Yangtze River Basin of China. The seasonal wet-dry alternation in soil affects the transformation of soil nitrogen and the application effect of nitrogen fertilizers. From the perspective of annual rotation, this study explored the differences in the effects of nitrogen fertilizer management on crop yield and nitrogen distribution in the rice-rapeseed rotation system, so as to provide a scientific basis for the efficient utilization of annual nitrogen fertilizer in the rice-rapeseed rotation system.【Method】The field experiment was located in Wuhan, Hubei Province, and was founded in 2012. This study selected 11 consecutive rice-rapeseed rotation years from 2012 to 2023 to conduct the experiment, four nitrogen fertilizer treatments were designed in the experiment: (1) no nitrogen application in both the rapeseed and rice seasons (N0-0); (2) applying 150 kg N·hm^-2 of nitrogen fertilizer in both the rice and rapeseed seasons (N150-150); (3) adding 75 kg N·hm^-2 of nitrogen fertilizer to the rice season on the basis of treatment (2) (N225-150); (4) adding 75 kg N·hm^-2 of nitrogen fertilizer to the rapeseed season on the basis of treatment (2) (N150-225). The related indicators such as crop yield, annual system energy yield, yield components, nitrogen accumulation and soil nitrogen supply capacity were analyzed.【Result】There were differences in the response of yield and nitrogen accumulation to nitrogen fertilizer management between rapeseed and rice. When the nitrogen application rate was N150-150 in both rice and rapeseed seasons, compared with no nitrogen application, the yields of rapeseed and rice increased by an average of 207.1% and 92.4%, respectively, and the nitrogen accumulation increased by an average of 253.2% and 114.7%, respectively. Compared with the N150-150 treatment, further application of nitrogen fertilizer during the rice season increased rice and rapeseed yields by 9.6% and 6.6%, respectively, while application of nitrogen fertilizer during the rapeseed season increased yields by 4.4% and 23.7%, respectively. Nitrogen application mainly increased crop yield by increasing the number of siliques per plant in rapeseed, the number of effective panicles per area in rice, and the number of grains per panicle, with rapeseed having a higher yield increase effect. In addition, from the analysis of the annual nitrogen fertilizer yield-increasing effect in the rotation system, compared with the application of 150 kg·hm^-2 of nitrogen in both rice and rapeseed seasons, the system energy yield and nitrogen accumulation of the rotation system under N225-150 treatment increased by 8.4% and 13.5%, respectively, and those under N150-225 treatment increased by 10.6% and 18.4%, respectively; at the same time, the annual nitrogen fertilizer utilization rate in the rice season with additional nitrogen application was 2.7 percentage points lower than that in the rapeseed season with additional nitrogen application, which might be related to the fact that the soil basic nitrogen supply in the rice season was 91.1% higher than that in the rapeseed season, resulting in a lower demand for high nitrogen input.【Conclusion】Therefore, in actual production, the annual nitrogen allocation should be adjusted according to the crop nitrogen requirements and soil nitrogen supply characteristics of the rotation system. In the rapeseed season, the nitrogen fertilizer application could be appropriately increased to achieve high yield, while in the rice season, the soil nitrogen supply capacity should be fully utilized, and the nitrogen fertilizer application should be appropriately controlled to achieve stable and efficient production of the rice-rapeseed rotation system.

Key words: rice-rapeseed rotation, nitrogen fertilizer management, crop yield, system energy yield, nitrogen accumulation, nitrogen fertilizer utilization rate, nitrogen apparent balance