title: Biochar applied at an appropriate rate can avoid increasing NH3volatilization dramatically in rice paddy soil.
abstract: Biochar application can increase carbon sequestration and reduce greenhouse gases emissions in paddy soils. However, its influence on ammonia (NH3) volatilization is neglected. This soil column study was conducted using two biochars (wheat straw pyrolyzed at 500 °C and 700 °C) with two application rates (0.5 wt% and 3 wt%) to evaluate their impact on NH3volatilization from rice paddy. Results showed that biochar application did not change NH3volatilization fluxes pattern after N fertilization. Four biochar treatments recorded higher NH3volatilization (20.50-31.88 kg N ha-1) compared with the control (18.65 kg N ha-1). Especially, two 3 wt% biochar treatments had significantly 40.8-70.9% higher NH3volatilization than control. After the basal and first supplementary fertilization, the floodwater pH values were 7.61-7.79 and 7.51-7.76 under biochar treatments, higher than control (7.37 and 7.16, respectively). Meanwhile, after three split N fertilizations, the pH of surface soil received biochar increased by 0.19-0.45, 0.19-0.39, and 0.01-0.21 units, in comparison with the control soil. Furthermore, 3 wt% biochar treatments had higher floodwater and surface soil pH values than 0.5 wt% biochar treatments. Higher NH4+-N and lower NO3--N concentrations of surface soil under biochar application were observed compared with control at tillering stage, whereas they were at similar level at jointing stage. The increased NH3volatilization at 3 wt% biochar treatments is attributed to increased pH of surface floodwater and soil, and reduced nitrification processes induced by biochar application. Biochar should be applied at lower rate to rice paddy soil, considering the NH3volatilization.
authors.affiliation: Institute of Agricultural Resources and Environment, Jiangsu Academy of Agriculture Sciences, Nanjing, 210014, China; State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China. Electronic address: jaasfengyang@163.com.
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China; Collaborative Innovation Center of Sustainable Forestry in Southern China of Jiangsu Province, Nanjing Forestry University, Nanjing, 210037, China. Electronic address: ww018150@163.com.
authors.forename: Haijun
authors.initials: H
authors.lastname: Sun
authors.affiliation: Institute of Agricultural Resources and Environment, Jiangsu Academy of Agriculture Sciences, Nanjing, 210014, China. Electronic address: njxuelihong@gmail.com.
authors.forename: Lihong
authors.initials: L
authors.lastname: Xue
authors.affiliation: Institute of Agricultural Economics and Information, Jiangsu Academy of Agriculture Sciences, Nanjing, 210014, China. Electronic address: liusyang@126.com.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Institute of Agricultural Resources and Environment, Jiangsu Academy of Agriculture Sciences, Nanjing, 210014, China. Electronic address: 434533037@qq.com.
authors.forename: Qian
authors.initials: Q
authors.lastname: Gao
authors.affiliation: School of Environmental and Resource Sciences, Zhejiang A&F Univerisity, Lin'an, Hangzhou, 311300, China. Electronic address: kkping111@163.com.
authors.forename: Kouping
authors.initials: K
authors.lastname: Lu
authors.affiliation: Institute of Agricultural Resources and Environment, Jiangsu Academy of Agriculture Sciences, Nanjing, 210014, China. Electronic address: lzyang@issas.ac.cn.
authors.forename: Linzhang
authors.initials: L
authors.lastname: Yang
mesh_terms: D000641:Ammonia / Q000032:analysis / Q000737:chemistry*; D002606:Charcoal; D012275:Oryza; D012989:Soil Pollutants / Q000737:chemistry*; D014908:Triticum; D014835:Volatilization
chemical_list: D012989:Soil Pollutants; C540010:biochar; D002606:Charcoal; D000641:Ammonia
keywords: Biochar; NH(3) volatilization; NH(4)(+)-N; Paddy soil; pH