Biochar stimulates nitrogen loss in anoxic soil through ammonium oxidation coupled with iron reduction
Bo Yi,
Qichun Zhang,
Steven J. Hall,
Xiang Zou,
Wenjuan Huang,
Wenjuan Yu,
Qinsi He,
Peiyu Cao,
Jing Hou,
Jiuwei Song,
Hongjie Di,
Chaoqun Lu
Affiliations
Bo Yi
Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, State Key Laboratory of Soil Pollution Control and Safety, Zhejiang University, Hangzhou, PR China; Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA
Qichun Zhang
Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, State Key Laboratory of Soil Pollution Control and Safety, Zhejiang University, Hangzhou, PR China; Corresponding author.
Steven J. Hall
Department of Plant and Agroecosystem Sciences, University of Wisconsin-Madison, Madison, WI, USA
Xiang Zou
Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, State Key Laboratory of Soil Pollution Control and Safety, Zhejiang University, Hangzhou, PR China
Wenjuan Huang
Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA
Wenjuan Yu
State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou, Zhejiang, PR China
Qinsi He
College of Water Conservancy and Civil Engineering, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia, PR China
Peiyu Cao
Department of Global Development, College of Agriculture and Life Sciences, Cornell University, Ithaca, NY, USA
Jing Hou
Department of Statistics, Iowa State University, Ames, IA, USA
Jiuwei Song
Yancheng Teachers University, Yancheng, Jiangsu, PR China
Hongjie Di
Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, State Key Laboratory of Soil Pollution Control and Safety, Zhejiang University, Hangzhou, PR China
Chaoqun Lu
Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA
Anaerobic ammonium oxidation coupled with iron (Fe) reduction, known as Feammox, is an important nitrogen (N)-cycling pathway in anoxic soils. Biochar, widely employed as a soil amendment, has been reported to influence N dynamics through its redox-active moieties, but the effects on Feammox of biochar produced with different pyrolysis temperatures remain poorly understood. We conducted a slurry incubation in rice-paddy soil with 15N-isotope tracing to examine the impact of biochar pyrolyzed at 300 °C and 600 °C on Feammox under different Fe availability conditions (addition of ferrihydrite, goethite, or no Fe). Biochar pyrolysis temperature and Fe availability impacted rates of Feammox. Specifically, adding biochar pyrolyzed at 600 °C to soil at a 2 % mass ratio stimulated N loss through Feammox by 0.03 to 0.07 μg N g−1 soil d-1, likely by facilitating electron transfer via its surface redox-active moieties. Feammox was highly correlated with Fe reduction despite contributing only a small fraction to overall Fe reduction. Feammox rates were greatest with ferrihydrite addition and lowest with no Fe addition, and correlated with the abundance of a known Feammox bacterium (Acidimicrobiaceae bacterium A6). In contrast, biochar pyrolyzed at 300 °C did not stimulate Feammox, likely due to a lack of electron shuttling capacity. Overall, our findings highlight a stimulation effect of biochar pyrolyzed at high temperature on promoting N loss as dinitrogen, underscoring its potential utility for environmentally-friendly removal of excess N from anoxic soil.
