title: Different effects of biochar and a nitrification inhibitor application on paddy soil denitrification: A field experiment over two consecutive rice-growing seasons.
abstract: Biochar and nitrification inhibitors are increasingly being proposed as amendments to improve nitrogen use efficiency (NUE). However, their effects on soil denitrification and the major N loss in rice paddies over an entire rice-growing season are not well understood. In this study, using intact soil core incubation combined with N2/Ar technique, the impacts of biochar and a nitrification inhibitor (Ni), 2-chloro-6-(trichloromethyl)-pyridine, on rice yield and soil denitrification, as well as ammonia (NH3) volatilization, were investigated over two rice-growing seasons in the Taihu Lake region of China. Field experiments were designed with four treatments: N0 (no N applied), N270 (270kg N ha-1applied), N270+C (25tha-1biochar applied) and N270+Ni (2-chloro-6- [trichloromethyl] -pyridine, 1.35kgha-1N applied). Compared with single application of N fertilizer alone (N270), biochar (N270+C) and Ni (N270+Ni) applications increased rice yields by 4.2-5.2% and 6.2-7.3%, respectively. The cumulative N2-N and NH3-N losses in different treatments varied from 11.9 to 21.8% and from 11.5 to 22.0% of the applied N, respectively. Compared with the single application of N fertilizer, the Ni application increased total NH3emission by 4.0-20.6% and significantly decreased total N2-N emission by 9.7-19.4% (p<0.05), while the biochar application increased total NH3and N2-N emissions by 8.6-17.9% and 3.3-9.7%, respectively. Overall, the biochar application resulted in an 11-15% higher net gaseous N than the Ni application. Although the biochar application may increase the rice yield and consequently the plant N uptake, it also promoted N loss more than Ni. Therefore biochar may not be good for maintaining soil fertility over a long period. Instead, applying Ni may be an optimal practice to ensure food security, while decreasing gaseous N loss, for rice production in the Taihu Lake region of China.
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China; Changshu Agro-ecological Experimental Station, Chinese Academy of Sciences, Changshu 215555, China.
authors.forename: Shuwei
authors.initials: S
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; Changshu Agro-ecological Experimental Station, Chinese Academy of Sciences, Changshu 215555, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Shan
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; Changshu Agro-ecological Experimental Station, Chinese Academy of Sciences, Changshu 215555, China.
authors.forename: Yongqiu
authors.initials: Y
authors.lastname: Xia
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China; Changshu Agro-ecological Experimental Station, Chinese Academy of Sciences, Changshu 215555, China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Tang
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China; Changshu Agro-ecological Experimental Station, Chinese Academy of Sciences, Changshu 215555, China.
authors.forename: Longlong
authors.initials: L
authors.lastname: Xia
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; Changshu Agro-ecological Experimental Station, Chinese Academy of Sciences, Changshu 215555, China.
authors.forename: Jinghui
authors.initials: J
authors.lastname: Lin
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; Changshu Agro-ecological Experimental Station, Chinese Academy of Sciences, Changshu 215555, China. Electronic address: yanxy@issas.ac.cn.
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Yan
keywords: Biochar; Denitrification; N(2)/Ar technique; NH(3) volatilization; Nitrification inhibitors; Rice paddies