Ecological and physiological implications of nitrogen oxide reduction pathways on greenhouse gas emissions in agroecosystems
2019
Yoon, Sukhwan | Song, Bongkeun | Phillips, Rebecca L. | Chang, Jin | Song, Min Joon
Microbial reductive pathways of nitrogen (N) oxides are highly relevant to net emissions of greenhouse gases (GHG) from agroecosystems. Several biotic and abiotic N-oxide reductive pathways influence the N budget and net GHG production in soil. This review summarizes the recent findings of N-oxide reduction pathways and their implications to GHG emissions in agroecosystems and proposes several mitigation strategies. Denitrification is the primary N-oxide reductive pathway that results in direct N₂O emissions and fixed N losses, which add to the net carbon footprint. We highlight how dissimilatory nitrate reduction to ammonium (DNRA), an alternative N-oxide reduction pathway, may be used to reduce N₂O production and N losses via denitrification. Implications of nosZ abundance and diversity and expressed N₂O reductase activity to soil N₂O emissions are reviewed with focus on the role of the N₂O-reducers as an important N₂O sink. Non-prokaryotic N₂O sources, e.g. fungal denitrification, codenitrification and chemodenitrification, are also summarized to emphasize their potential significance as modulators of soil N₂O emissions. Through the extensive review of these recent scientific advancements, this study posits opportunities for GHG mitigation through manipulation of microbial N-oxide reductive pathways in soil.
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