Biogas slurry application could potentially reduce N2O emissions and increase crop yield

The huge excrement quantity from the increasing large-scale livestock stressed the ecological, environmental deterioration. As a major benefit for handling livestock manure, the slurry of biogas (BS) is developed during the production of biogas that might increase plant productivity. However, nitrous oxide (N2O) emissions from BS are considered a significant danger to the environment due to global warming potential. Furthermore, applying different proportions of BS combined with chemical fertilizer (CF) on N2O productions in the North China Plain (NCP) remains unclear. Herein, two sequential field trials were performed by maize-wheat rotations to substitute the CF by BS and reduce N2O emissions while keeping the crop yield stable. Four treatments were conducted, including T1, T3, T6, and CK. A total of 226.5 kg N ha(-1) used in the maize-wheat rotation system. Additionally, different ratios of BS (100%, 80%, and 50%) combined with CF were used in wheat season in the tillering stage. Results showed integrated applications of BS with CF have potential for reducing N2O emission. Our findings showed that the maximum grain yield of CF was 6250 kg ha(-1), which might be achieved by applying 38% BS and 62% of CF. This ratio yielded 1.03 kg ha(-1) N2O emissions, which was 15% lesser than the N2O emission of CK, 1.21 kg ha(-1). Considering whole growing period of wheat biogas treatments significantly reduced the cumulative N2O emissions from 17% to 26% compared to CF. To achieve maximum yield and minimum N2O emissions, an optimum 38% BS ratio has been suggested. The integrated use of BS and CF provided the greatest grain yield because of necessary nutrients provided by both slurry and CF. Consequently, N2O emissions reduced based on frequency and type of fertilizer. In conclusion, 38% ratio of BS combined with 62% CF would be a suitable approach to mitigate N2O emission and simultaneously increase crop yield in NCP. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The integrated application of BS and CF shows potential in reducing N2O emissions, achieving maximum yield and minimum N2O emissions by optimizing the ratio of BS and CF. The study suggests that in wheat rotations, a ratio of 38% BS combined with 62% CF can reduce N2O emissions while maintaining stable crop yield.