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The coupling interaction of NO2− with NH4+ or NO3− as an important source of N2O emission from agricultural soil in the North China Plain

Author:
Zhang, Yuanyuan, Guo, Guangxia, Wu, Hai, Mu, Yujing, Liu, Pengfei, Liu, Junfeng, Zhang, Chenglong
Source:
The Science of the total environment 2019 v.692 pp. 82-88
ISSN:
0048-9697
Subject:
agricultural land, agricultural soils, ammonium, denitrification, fertilizer application, genes, greenhouse gas emissions, intermediate product, nitrates, nitric oxide, nitrification, nitrites, nitrogen cycle, nitrous oxide, nitrous oxide production, nitrous-oxide reductase, China
Abstract:
NO₂⁻ plays a crucial role in regulating N₂O formation from the soil, while how it affects the production of soil N₂O is still not well understood. In this study, N₂O and NO emissions from an agricultural field of the North China Plain (NCP) were comparatively investigated under five different fertilizer treatments (NH₄⁺, NO₃⁻, NO₂⁻, NH₄⁺ + NO₂⁻ and NO₃⁻ + NO₂⁻). Additionally, soil NH₄⁺, NO₂⁻ and NO₃⁻ concentrations and the abundance of functional genes associated with nitrogen cycling were also analyzed in the incubation experiment. The results showed that the N₂O average fluxes from the complex treatments of NO₂⁻ + NO₃⁻ were 1.4–2.4 times the sum of those from the separate treatments of NO₂⁻ and NO₃⁻ whereas from the complex treatments of NO₂⁻ + NH₄⁺ were a factor of 1-1.4 larger than those from the separate treatments of NO₂⁻ and NH₄⁺, indicating the coupling interaction of NO₂⁻ with NH₄⁺ or NO₃⁻ makes a remarkable contribution to N₂O emission from the soil. Significant reduction of the activity of N₂O reductase was found in the soil with the addition of NO₂⁻, which favored the accumulation of N₂O formed through nitrification of NH₄⁺ and denitrification of NO₂⁻, resulting in relatively high N₂O emissions from the complex treatments. As the intermediate product of nitrification and denitrification, NO₂⁻ produced is also expected to interact with NH₄⁺ or NO₃⁻ to promote N₂O emission from the soil, especially during fertilization events when NO₂⁻ is easily accumulated due to the acceleration of the nitrification and denitrification processes.
Agid:
6536900