Yield-scaled N₂O emissions in a winter wheat–summer corn double-cropping system
2012
Qin, Shuping | Wang, Yuying | Hu, Chunsheng | Oenema, O. (Oene) | Li, Xiaoxin | Zhang, Yuming | Dong, Wenxu
Emissions of nitrous oxide (N₂O) from agricultural soils contribute to global warming and stratospheric ozone depletion. Applications of fertilizer nitrogen (N) increase N₂O emission, but also increase agricultural production. Here, we report on the responses of crop yield, N₂O emission and yield-scaled N₂O emission (N₂O emission per unit N uptake by grain and aboveground biomass) to different N fertilizer rates in a winter wheat–summer corn double-cropping system in the North China Plain. Soil N₂O emission measurements were carried out for two years in a long-term field experiment, under semi-arid conditions with four flood irrigations events per year. Our results indicated that N₂O emissions were linear functions and yield-scaled N₂O emissions were cubic functions of N fertilizer application rate. Yield-scaled N₂O emissions were lowest at application rates of 136 kg N ha⁻¹ yr⁻¹. Using a quadratic-plateau model, it was found that maximal crop yields were achieved at an application rate of 317 kg N ha⁻¹ yr⁻¹, which is 20% less than current practice. This level is suggested to be a compromise between achieving food security and mitigation N₂O emissions.
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