|VAN ZWIETEN, LUCAS - New South Wales Agriculture|
|KAMMANN, CLAUDIA - Justus-Liebig University|
|SINGH, B - New South Wales Agriculture|
|CAYUELA, MARIA LUZ - University Of Sevilla|
|CLOUGH, TIM - Lincoln University - New Zealand|
|KIMBER, STEPHEN - New South Wales Agriculture|
|JOSEPH, STEPHEN - University Of New South Wales|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 7/14/2014
Publication Date: 3/1/2015
Citation: Van Zwieten, L., Kammann, C., Singh, B.P., Cayuela, M., Clough, T., Spokas, K.A., Kimber, S., Joseph, S. 2015. Biochar effects on gaseous losses of N2O and CH4. In: Biochar for Environmental Management: Science and Technology II. Routledge: Abingdon, UK, p. 489-520.
Technical Abstract: The flux of N2O from soil is controlled by both biological and abiotic processes resulting in production and consumption. In a recent review by Butterbach-Bahl et al., (2013), key processes that contribute to N2O formation in soils included: 1) chemical decomposition of hydroxylamine during autotrophic and heterotrophic nitrification, 2) chemodenitrification of soil nitrite and abiotic decomposition of ammonium nitrate in the presence of light, humidity and reacting surfaces, 3) nitrifier-denitrification within the same nitrifying micro-organism, 4) coupled nitrification–denitrification by distinct micro-organisms (production of nitrate by nitrite oxidizers, which is immediately denitrified in situ by denitrifiers), 5) denitrification conducted by organisms capable of using nitrogen oxides as alternative electron acceptors under O2-limiting environmental conditions, 6) co-denitrification of organic N compounds with NO, and 7) nitrate ammonification or dissimilatory nitrate reduction to ammonium. The relative contribution of each to total N2O emissions depends on the soil characteristics (texture, available carbon, pH, microbial activity), temperature and soil water. The hypotheses that biochar reduces emissions of N2O will be tested via a meta-analysis of published data, and we further build on our understanding of the underlying processes where biochar may impact GHG flux. We review the literature on the impacts of biochar on CH4 processes in soil and also explore the role of pyrolysing biomass in reducing soil emissions of N2O. This Chapter aims to guide further work in this field to reduce the uncertainty in analysis of biochar on GHG impacts.