Restoring wetlands on intensive agricultural lands modifies nitrogen cycling microbial communities and reduces N.sub.2O production potential.

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Publisher: Elsevier B.V.
Document Type: Report; Brief article
Length: 401 words

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Keywords Functional genes; Land use change; Land management; Nitrogen fixation; Denitrification; Ammonia oxidation Highlights * Land use type is the main determinant for N.sub.2O production potential in the Delta. * All processes (nitrification, denitrification, DNRA) contribute to N.sub.2O production. * Drained soils show the highest N.sub.2O production potential. * Wetland restoration will increase the potential for N.sub.2O reduction to N.sub.2. * Restored wetlands in the Delta have high nitrogen fixing potential. Abstract The concentration of nitrous oxide (N.sub.2O), an ozone-depleting greenhouse gas, is rapidly increasing in the atmosphere. Most atmospheric N.sub.2O originates in terrestrial ecosystems, of which the majority can be attributed to microbial cycling of nitrogen in agricultural soils. Here, we demonstrate how the abundance of nitrogen cycling genes vary across intensively managed agricultural fields and adjacent restored wetlands in the Sacramento-San Joaquin Delta in California, USA. We found that the abundances of nirS and nirK genes were highest at the intensively managed organic-rich cornfield and significantly outnumber any other gene abundances, suggesting very high N.sub.2O production potential. The quantity of nitrogen transforming genes, particularly those responsible for denitrification, nitrification and DNRA, were highest in the agricultural sites, whereas nitrogen fixation and ANAMMOX was strongly associated with the wetland sites. Although the abundance of nosZ genes was also high at the agricultural sites, the ratio of nosZ genes to nir genes was significantly higher in wetland sites indicating that these sites could act as a sink of N.sub.2O. These findings suggest that wetland restoration could be a promising natural climate solution not only for carbon sequestration but also for reduced N.sub.2O emissions. Author Affiliation: (a) University of Tartu, Institute of Ecology and Earth Sciences, Department of Geography, Tartu, Estonia (b) University of California, Berkeley, Department of Environmental Science, Policy and Management, Berkeley, CA, USA (c) Lawrence Berkeley National Laboratory, Berkeley, CA, USA (d) Climate and Agriculture Group, Agroscope, Switzerland (e) Stanford University, Stanford, CA, USA (f) Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, IL, USA * Corresponding author. Vanemuise st 46-241, 50410, Tartu, Estonia. Article History: Received 11 May 2021; Revised 3 August 2021; Accepted 17 August 2021 Byline: Kuno Kasak [] (a,*), Mikk Espenberg (a), Tyler L. Anthony (b), Susannah G. Tringe (c), Alex C. Valach (d), Kyle S. Hemes (e), Whendee L. Silver (b), Ülo Mander (a), Keit Kill (a), Gavin McNicol (f), Daphne Szutu (b), Joseph Verfaillie (b), Dennis D. Baldocchi (b)

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Gale Document Number: GALE|A677203764