Canada's Progress in Understanding N2O and other GHGs Emissions from Manure-amended Soils

The application of manure to soil is a major source of greenhouse gas (GHG) emissions in the agricultural sector. However, current estimates of GHG emissions from this source in Canada may not accurately reflect the true extent of these emissions, as there is a lack of sufficient coefficients. This knowledge gap can have significant implications for the estimation of national GHG emissions in the National Inventory Report. To address this issue, this study aims to systematically quantify the studied regions, research scopes, techniques, livestock types, management, field crops, and sources of GHG (CO2, N2O, CH4) in the published articles. We searched the Scopus database (Elsevier) using the following formula: (TITLE-ABS-KEY (canad*) OR AFFILCOUNTRY (Canada) AND TITLE-ABS-KEY (manure OR slurry OR compost OR litter OR excreta OR “animal waste” OR “livestock waste”) AND TITLE-ABS-KEY ("greenhouse gas" OR CO2 OR CH4 OR N2O) OR TITLE-ABS-KEY ("carbon dioxide" OR methane OR "nitrous oxide")) AND PUBYEAR > 1990. We retrieved 1151 articles published between January 1, 1990, and May 31, 2022. After excluding data articles, reviews, and articles that did not address GHG emissions, we analyzed 141 articles. Our findings indicate that studies of GHG emissions from manure-amended soils have increased by 66% after 2011 compared to before 2011. Single-year and multiple-year studies were equally represented. However, only 37% of studies estimated year-round GHG emissions. Furthermore, the provinces of British Columbia, Ontario, and Quebec accounted for 68% of the studies. Dairy and beef cattle manure were the most frequently studied livestock types, accounting for 70% of the studies. Swine and poultry manure were studied less often. Carbon dioxide and nitrous oxide emissions were estimated in 94% and 87% of the studies, while fewer measurements of ammonia or soil methane. Our study provides a systematic analysis of previous studies on GHG emissions from manure-amended soils in Canada. These findings can be compared to the sources of emissions to identify data gaps for accurate estimation of national GHG emissions from the agricultural sector. Further analysis will be presented during the presentation.