Nitrogen inputs are more important than denitrifier abundances in controlling denitrification-derived N2O emission from both urban and agricultural soils

Hui-Juan Xu; Xiao-Ru Yang; Shun Li; Xi-Mei Xue; Shuai Chang; Hu Li; Brajesh K Singh; Jian-Qiang Su; Yong-Guan Zhu

doi:10.1016/j.scitotenv.2018.10.001

Nitrogen inputs are more important than denitrifier abundances in controlling denitrification-derived N₂O emission from both urban and agricultural soils

Sci Total Environ. 2019 Feb 10;650(Pt 2):2807-2817. doi: 10.1016/j.scitotenv.2018.10.001. Epub 2018 Oct 2.

Authors

Hui-Juan Xu¹, Xiao-Ru Yang², Shun Li³, Xi-Mei Xue², Shuai Chang⁴, Hu Li², Brajesh K Singh⁵, Jian-Qiang Su⁶, Yong-Guan Zhu⁷

Affiliations

¹ Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
² Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
³ Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Center for Applied Geosciences, University of Tübingen, Tübingen 72074, Germany.
⁴ Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China.
⁵ Hawkesbury Institute for the Environment, University of Western Sydney, Penrih 2751, New South Wales, Australia; Global Centre for Land-Based Innovation, University of Western Sydney, Penrith 2751, New South Wales, Australia.
⁶ Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China. Electronic address: jqsu@iue.ac.cn.
⁷ Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; State Key Lab of Urban and Regional Ecology, Research Center for Eco-environmental Sciences, Beijing 100085, China.

PMID: 30373058
DOI: 10.1016/j.scitotenv.2018.10.001

Abstract

Cities are increasingly being recognized as important contributors in global warming, for example by increasing atmospheric nitrous oxide (N₂O). However, urban ecosystems remain poorly understood due to their functional complexity. Further, few studies have documented the microbial processes governing the N₂O emissions from urban soils. Here, a field study was performed to assess in situ N₂O emissions in an urban and agricultural soil located in Xiamen, China. The mechanisms underlying the difference in N₂O emission patterns in both soils were further explored in an incubation experiment. Field investigations showed that N₂O emission (3.5-19.0 μg N₂O-N m^-2 h^-1) from the urban soil was significantly lower than that from the agricultural soil (25.4-18,502.3 μg N₂O-N m^-2 h^-1). Incubation experiments showed that the urban soil initially emitted lower denitrification-derived N₂O because of the lower nirS (encoding nitrite reductases) abundances, whereas overall N₂O accumulation during the incubation was mainly controlled by the initial nitrate content in soil. Nitrate addition in a short period (5 days) did not change the total bacterial and denitrifier abundances or the soil bacterial community composition, but significantly altered the relative distribution of some key genera capable of denitrification. Although the urban soil exhibited lower N₂O emission than its agricultural counterpart in this study, the expanding urban green areas should be taken into account when building N₂O emission reduction targets.

Keywords: Denitrification; Denitrifier; Illumina sequencing; Nitrous oxide; Urbanization.