Global nitrous oxide emission factors from agricultural soils after addition of organic amendments: A meta-analysis

• Published in: Agriculture, ecosystems & environment Vol. 236; pp. 88 - 98
• Main Authors: Charles, Anaïs, Rochette, Philippe, Whalen, Joann K., Angers, Denis A., Chantigny, Martin H., Bertrand, Normand
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 02.01.2017; Elsevier BV
• Subjects: Agricultural land; Agrochemicals; Animal wastes; Anthropogenic factors; Biosolids; Carbon/nitrogen ratio; Composting; Composts; Crop residues; Crops; Emission analysis; Farming systems; Fertilization; Fertilizers; Greenhouse gas inventory; Human influences; Intergovernmental Panel on Climate Change; Liquid manure; Meta-analysis; Modeling; Nitrogen; Nitrous oxide; Organic by-products; Organic soils; Rainfall; Redox potential; Residues; Reviews; Risk; Risk groups; Sludge; Slurries; Soil amendment; Soil analysis; Soil characteristics; Soil chemistry; Soil conditions; Soils; Solid wastes; Studies; Weighting procedure; Farming systems; Greenhouse gas inventory; Organic by-products; Fertilization; Weighting procedure; Modeling
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2016.11.021

•The meta-analysis included 38 studies (422N2O emission factors in 12 countries).•The weighted-REML showed higher synthetic-N emission factors with better N2O coverage.•We propose a global emission factor for organic inputs of 0.57±0.3% of N applied.•We encourage the use of three identified N2O risk classes of organic amendments.•Emission factors were 2.8 times greater in fine- than in coarse-textured soils. Agricultural soils receiving synthetic fertilizers and organic amendments containing nitrogen contribute a large part to anthropogenic nitrous oxide (N2O) emissions. As a source of nitrate that undergoes reduction to N2O, organic amendments also change soil C availability and redox potential, which influences the N2O emission factor (EF) of organically-amended soils. The objective of this study was to conduct a meta-analysis of N2O EF from agricultural soils receiving organic amendments. A global survey of peer-reviewed literature resulted in the selection of 38 studies including 422 observations at 43 sites in 12 countries. The analysis yielded a global EF for all organic sources, EForg, equal to 0.57±0.30%, which is lower than the IPCC default EF of 1 for synthetic fertilizers. Three groups of organic amendments with similar EFs were identified: the high-risk group including animal slurries, waste waters and biosolids (1.21±0.14%); the medium-risk group including solid manure, composts+fertilizers, and crop residues+fertilizers (0.35±0.13%); and the low-risk group including composts, crop residues, paper mill sludge and pellets (0.02±0.13%). The EF was higher when soils received organic amendments in combination with synthetic fertilizers, such as liquid manures+fertilizers (2.14±0.53%), composts+fertilizers (0.37±0.24%), and crop residues+fertilizers (0.59±0.27%). The EF was modulated by amendment (C/N ratio), soil (texture, drainage, organic C and N) and climatic (precipitation) factors. For example, EFs were on average 2.8 times greater in fine-textured than coarse-textured soils. We recommend site-specific EFs that consider organic amendment chemistry, soil characteristics, climate conditions and whether the organic amendment is applied alone or in combination with synthetic fertilizers.