Denitrification dominates dissimilatory nitrate reduction across global natural ecosystems

• Published in: Global change biology Vol. 30; no. 3; pp. e17256 - n/a
• Main Authors: Deng, Danli, He, Gang, Ding, Bangjing, Liu, Wenzhi, Yang, Zhengjian, Ma, Lin
• Format: Journal Article
• Language: English
• Published: England 01.03.2024
• Subjects: Ammonium Compounds; anammox; Carbon; Denitrification; DNRA; Ecosystem; latitude; Nitrates - analysis; Nitrogen; nitrogen loss; nitrogen retention; Oxidation-Reduction; Soil; DNRA; nitrogen loss; nitrogen retention; anammox; latitude
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/gcb.17256

Denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) are three competing processes of microbial nitrate reduction that determine the degree of ecosystem nitrogen (N) loss versus recycling. However, the global patterns and drivers of relative contributions of these N cycling processes to soil or sediment nitrate reduction remain unknown, limiting our understanding of the global N balance and management. Here, we compiled a global dataset of 1570 observations from a wide range of terrestrial and aquatic ecosystems. We found that denitrification contributed up to 66.1% of total nitrate reduction globally, being significantly greater in estuarine and coastal ecosystems. Anammox and DNRA could account for 12.7% and 21.2% of total nitrate reduction, respectively. The contribution of denitrification to nitrate reduction increased with longitude, while the contribution of anammox and DNRA decreased. The local environmental factors controlling the relative contributions of the three N cycling processes to nitrate reduction included the concentrations of soil organic carbon, ammonium, nitrate, and ferrous iron. Our results underline the dominant role of denitrification over anammox and DNRA in ecosystem nitrate transformation, which is crucial to improving the current global soil N cycle model and achieving sustainable N management. The global patterns and drivers of relative contributions of denitrification, anammox, and DNRA to soil or sediment nitrate reduction remain unknown, limiting our understanding of global nitrogen balance and sustainable nitrogen management. Our meta‐analysis indicated that denitrification contributed up to 66.1% of total nitrate reduction globally, being significantly greater in estuarine and coastal ecosystems. Anammox and DNRA accounted for 12.7% and 21.2% of total nitrate reduction, respectively. The local environmental factors controlling the relative contributions of these nitrogen cycling processes to nitrate reduction included the concentrations of soil organic carbon, ammonium, nitrate, and ferrous iron.