Review of research on methane and nitrous oxide emissions from manure storage across Canada from 1990 to 2023

In 2022, Canadian greenhouse gas (GHG) emissions related to manure management were estimated at 7.8 Mt carbon dioxide equivalent, with methane (CH 4 ) emissions primarily from swine and nitrous oxide (N 2 O) emissions mainly from beef production. Because Canada’s agriculture spans diverse climates and livestock types, this estimate carries uncertainty that further research could reduce. This study reviewed 144 Canadian articles published between 1990 and 2023 to compare the current state of research associated with emissions of CH 4 and N 2 O from manure storage across Canada. Among these articles, 140 addressed CH 4 , 72 addressed N 2 O, including 68 for both gases. Research location counts (39 in Alberta, 39 in Quebec, and 34 in Ontario) reflected estimated CH 4 , but not N 2 O emissions. The emissions from liquid manure and solid manure were measured primarily through chamber (46) and incubation (43) methodologies. Dairy was the most studied livestock group, but further research is still needed, as CH 4 emissions continue to increase, along with N 2 O emissions from poultry manure. Mitigation practices for beef manure in Eastern Canada warrant further research, given the region’s humid temperate climate and its relative contribution to GHG emissions. Digesters (55) and composting (22) dominate mitigation studies, implying promise, while other practices remain understudied.