How nitrification-related N2O is associated with soil ammonia oxidizers in two contrasting soils in China?

Liuqing Yang; Gaodi Zhu; Xiaotang Ju; Rui Liu

doi:10.1016/j.scitotenv.2020.143212

How nitrification-related N₂O is associated with soil ammonia oxidizers in two contrasting soils in China?

Sci Total Environ. 2021 May 20:770:143212. doi: 10.1016/j.scitotenv.2020.143212. Epub 2020 Nov 24.

Authors

Liuqing Yang¹, Gaodi Zhu², Xiaotang Ju³, Rui Liu⁴

Affiliations

¹ Beijing Key Laboratory of Farmyard Soil Pollution Prevention-control and Remediation, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
² College of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou 311300, China.
³ College of Tropical Crops, Hainan University, Haikou 570228, China; Beijing Key Laboratory of Farmyard Soil Pollution Prevention-control and Remediation, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China. Electronic address: juxt@cau.edu.cn.
⁴ Beijing Key Laboratory of Farmyard Soil Pollution Prevention-control and Remediation, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China. Electronic address: rliu@cau.edu.cn.

PMID: 33257072
DOI: 10.1016/j.scitotenv.2020.143212

Abstract

As a key process contributing to N₂O emissions, nitrification is regulated by soil microbes and mainly affected by soil pH, NH₃ availability, temperature and O₂ availability. Current knowledge gaps include how nitrification-related N₂O is associated with soil microbes in different pH soils. In the current study, a microcosm incubation experiment was conducted with two contrasting soils of different pH (5.08, 8.30) under controlled conditions. The soils were amended with ammonium sulphate ((NH₄)₂SO₄, 50 mg N kg^-1) combined with or without nitrification inhibitors and incubated under 20 °C, 65% water hold capacity (WHC) for three weeks. N₂O fluxes, mineral nitrogen (N) concentrations and ammonia oxidizers populations were measured during the incubation to investigate the correlations of nitrification-related N₂O with ammonia oxidizers. The nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) was used to inhibit nitrification albeit to various inhibition effects with different soils. Acetylene (0.1% v/v C₂H₂), an inhibitor of AOA and AOB ammonia monooxygenase (AMO), was used to distinguish N₂O emissions by nitrifiers and denitrifiers. 1-octyne (5 μM aqueous), a selective specific AOB inhibitor, was used to assess the relative contributions of AOA and AOB to N₂O emissions. The results showed that N₂O yield for AOA and AOB varied with soil pH. AOB was the key microbial player in alkaline soil, contributing about 85% of nitrification-related N₂O. Conversely, about 78% of nitrification-related N₂O was contributed by AOA in acidic soil. Furthermore, there was a significant and positive relationship between mineral N (NO₂^-, NO₃^-), AOA and AOB populations and nitrification-related N₂O in alkaline soil. However, in acidic soil, NO₃^- concentration and AOA had significantly positive relationships with nitrification-related N₂O. To conclude, soil pH was a key factor affecting the contribution of ammonia oxidizers to nitrification-related N₂O emissions. AOA-related N₂O production dominated at low pH (5.08), while AOB-related N₂O was favored in alkaline soil (pH 8.3).

Keywords: Ammonia oxidizers; Nitrification inhibitors; Nitrification-related N(2)O emissions; Soil pH.

MeSH terms

Ammonia*
Archaea
China
Nitrification*
Oxidation-Reduction
Soil
Soil Microbiology

Substances

Soil
Ammonia