Ma Quan, Dai Dandan, Cao Yifan, Yu Qiaoqiao, Cheng Xiyang, Zhu Min, Ding Jinfeng, Li Chunyan, Guo Wenshan, Zhou Guisheng, Zhu Xinkai
Jiangsu Key Laboratory of Crop Genetics and Physiology, Agricultural College of Yangzhou University, Yangzhou, China.
Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou University, Yangzhou, China.
Front Plant Sci. 2024 Jul 25;15:1438215. doi: 10.3389/fpls.2024.1438215. eCollection 2024.
Rice-wheat and maize-wheat rotations are major cropping systems in the middle and lower reaches of Yangtze River in China, where high nitrogen (N) inputs and low N efficiency often exacerbate resource waste and environmental pollution. Due to the changes in factors such as soil properties and moisture content, the N fate and the N utilization characteristics of wheat in different rotations are significantly different. Efficient N management strategies are thus urgently required for promoting maximum wheat yield in different rotation systems while reducing N loss. A 2-year field experiment using isotopic (N) tracer technique was conducted to evaluate the fate of N-labeled urea in wheat fields and the distribution characteristics of N derived from different sources. The wheat yield and N use efficiency under various N rates (180 and 240 kg ha, abbreviated as N180 and N240) and preceding crops (rice and maize, abbreviated as R-wheat and M-wheat) were also investigated. The results showed that N240 increased N uptake and grain yield by only 8.77-14.97% and 2.51-4.49% compared with N 180, but decreased N agronomic efficiency (NAE) and N physiological efficiency (NPE) by 14.78-18.79% and 14.06-31.35%. N240 also decreased N recovery in plants by 2.8% on average compared with N180, and increased N residue in soil and N loss to the environment. Compared with that of basal N, the higher proportion of topdressing N was absorbed by wheat rather than lost to the environment. In addition, the accumulation of topdressing N in grain was much higher than that of basal N. Compared with that in R-wheat treatment, plants in M-wheat treatment trended to absorb more N and reduce unaccounted N loss, resulting in higher yield potential. Moreover, the M-wheat treatment increased N recovery in 0-20 cm soil but decreased 80-100 cm soil compared with R-wheat treatment, indicating a lower risk of N loss in deeper soil. Collectively, reducing N application rate and increasing the topdressing ratio is an effective way to balance sustainable crop yield for a secure food supply and environmental benefit, which is more urgent in rice-wheat rotation.
稻麦轮作和玉米-小麦轮作是中国长江中下游地区的主要种植制度，该地区高氮投入和低氮效率常常加剧资源浪费和环境污染。由于土壤性质和含水量等因素的变化，不同轮作中氮素的去向和小麦对氮的利用特性存在显著差异。因此，迫切需要有效的氮管理策略，以在不同轮作系统中提高小麦产量的同时减少氮素损失。通过为期两年的田间试验，利用同位素（氮）示踪技术评估了麦田中氮素标记尿素的去向以及不同来源氮素的分配特征。同时还研究了不同施氮量（180和240千克/公顷，简称为N180和N240）和前茬作物（水稻和玉米，简称为R-小麦和M-小麦）条件下的小麦产量和氮素利用效率。结果表明，与N180相比，N240仅使氮素吸收量增加了8.77%-14.97%，籽粒产量增加了2.51%-4.49%，但氮素农学效率（NAE）和氮素生理效率（NPE）分别降低了14.78%-18.79%和14.06%-31.35%。与N180相比，N240还使植株中氮素回收率平均降低了2.8%，并增加了土壤中的氮素残留和向环境中的氮素损失。与基肥相比，追肥中较高比例的氮素被小麦吸收而非流失到环境中。此外，追肥中氮素在籽粒中的积累量远高于基肥。与R-小麦处理相比，M-小麦处理的植株倾向于吸收更多的氮素并减少未计入的氮素损失，从而具有更高的产量潜力。此外，与R-小麦处理相比，M-小麦处理增加了0-20厘米土层中的氮素回收率，但降低了80-100厘米土层中的回收率，表明深层土壤中氮素损失风险较低。总体而言，降低施氮量并提高追肥比例是平衡可持续作物产量以保障粮食供应安全和环境效益的有效途径，这在稻麦轮作中更为迫切。
