title: Biochar decreases nitrogen oxide and enhances methane emissions via altering microbial community composition of anaerobic paddy soil.
abstract: Biochar application to agricultural soil is an appealing approach to mitigate nitrous oxide (N2O) and methane (CH4) emissions. However, the underlying microbial mechanisms are unclear. In this study, a paddy soil slurry was incubated anaerobically for 14d with biochar amendments produced from rice straw at 300, 500, or 700°C (B300, B500, and B700) to study their influences on greenhouse gas emissions. Illumina sequencing was used to characterize shift of soil bacterial and archaeal community composition. After peaking at day 1, N2O emission then sharply decreased to low levels while CH4started to emit at day 3 then continually increased with incubation. Compared to control soil (57.9mgkg-1soil), B300, B500, and B700 amendments decreased N2O peak emission to 17.9, 1.28, and 0.59mgkg-1, mainly due to increased soil pH. In contrast, the amendments enhanced CH4production from 58.2 to 93.4, 62.6, and 63.4mgkg-1at day 14 due to increased soil dissolved organic carbon. Abundance of denitrifying bacteria (e.g., Bacilli, 7.07-13.6 vs. 16.9%) was reduced with biochar amendments, especially with B500 and B700, contributing to the decreased N2O emissions. However, larger pore size of B500 and B700 (surface area of 68.1 and 161m2g-1) than B300 (4.40m2g-1) favored electron transfer between bacteria and iron minerals, leading to increased abundance of iron-reducing bacteria, (e.g., Clostridia, 48.2-50.6 vs. 33.3%), which competed with methanogens to produce CH4, thereby leading to lower increase in CH4emission. Biochar amendments with high pH and surface area might be effective to mitigate emission of both N2O and CH4from paddy soil.
authors.affiliation: Laboratory for Agricultural Wastes Treatment and Recycling, Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu 210014, People's Republic of China.
authors.forename: Ning
authors.initials: N
authors.lastname: Wang
authors.affiliation: Laboratory for Agricultural Wastes Treatment and Recycling, Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu 210014, People's Republic of China. Electronic address: czhizhou@hotmail.com.
authors.forename: Zhi-Zhou
authors.initials: ZZ
authors.lastname: Chang
authors.affiliation: Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, Fujian 361021, People's Republic of China.
authors.forename: Xi-Mei
authors.initials: XM
authors.lastname: Xue
authors.affiliation: Laboratory for Agricultural Wastes Treatment and Recycling, Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu 210014, People's Republic of China.
authors.forename: Jian-Guang
authors.initials: JG
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, People's Republic of China.
authors.forename: Xiao-Xia
authors.initials: XX
authors.lastname: Shi
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, People's Republic of China; Soil and Water Science Department, University of Florida, Gainesville, FL 32611, United States.
authors.forename: Lena Q
authors.initials: LQ
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, Jiangsu 210023, People's Republic of China. Electronic address: hongboli@nju.edu.cn.
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: Li
mesh_terms: D002606:Charcoal; D008697:Methane / Q000032:analysis*; D009609:Nitrous Oxide / Q000032:analysis*; D012275:Oryza; D012988:Soil Microbiology
chemical_list: C540010:biochar; D002606:Charcoal; D009609:Nitrous Oxide; D008697:Methane
keywords: Biochar; Greenhouse gases; Microbial communities; Paddy soil