Insight into the microbial nitrogen cycle in riparian soils in an agricultural region

Chunjian Lyu; Xiaojie Li; Huibin Yu; Yonghui Song; Hongjie Gao; Peng Yuan

doi:10.1016/j.envres.2023.116100

Insight into the microbial nitrogen cycle in riparian soils in an agricultural region

Environ Res. 2023 Aug 15;231(Pt 1):116100. doi: 10.1016/j.envres.2023.116100. Epub 2023 May 11.

Authors

Chunjian Lyu¹, Xiaojie Li¹, Huibin Yu¹, Yonghui Song², Hongjie Gao³, Peng Yuan¹

Affiliations

¹ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
² State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; College of Water Sciences, Beijing Normal University, Beijing, 100875, China. Electronic address: songyh@craes.org.cn.
³ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; College of Water Sciences, Beijing Normal University, Beijing, 100875, China. Electronic address: gaohj@craes.org.cn.

PMID: 37172685
DOI: 10.1016/j.envres.2023.116100

Abstract

Riparian zones are considered as an effective measure on preventing agricultural non-point source nitrogen (N) pollution. However, the mechanism underlying microbial N removal and the characteristics of N-cycle in riparian soils remain elusive. In this study, we systematically monitored the soil potential nitrification rate (PNR), denitrification potential (DP), as well as net N₂O production rate, and further used metagenomic sequencing to elucidate the mechanism underlying microbial N removal. As a whole, the riparian soil had a very strong denitrification, with the DP 3.17 times higher than the PNR and 13.82 times higher than the net N₂O production rate. This was closely related to the high soil NO₃^--N content. In different profiles, due to the influence of extensive agricultural activities, the soil DP, PNR, and net N₂O production rate near the farmland edge were relatively low. In terms of N-cycling microbial community composition, the taxa of denitrification, dissimilatory nitrate reduction, and assimilatory nitrate reduction accounted for a large proportion, all related to NO₃^--N reduction. The N-cycling microbial community in waterside zone showed obvious differences to the landside zone. The abundances of N-fixation and anammox genes were significantly higher in the waterside zone, while the abundances of nitrification (amoA&B&C) and urease genes were significantly higher in the landside zone. Furthermore, the groundwater table was an important biogeochemical hotspot in the waterside zone, the abundance of N-cycle genes near the groundwater table was at a relative higher level. In addition, compared to different soil depths, greater variation in N-cycling microbial community composition was observed between different profiles. These results reveal some characteristics of the soil microbial N-cycle in the riparian zone in an agricultural region and are helpful for restoration and management of the riparian zone.

Keywords: Agricultural non-point source; Nitrogen cycle; Riparian zone; Soil metagenome.

MeSH terms

Denitrification*
Nitrates / analysis
Nitrification
Nitrogen
Nitrogen Cycle
Soil Microbiology
Soil*

Substances

Soil
Nitrates
Nitrogen