The greenhouse gas (GHG) sources and carbon (C) sinks of Ontario’s agricultural soils and the impacts of management practices and potential strategies to reduce emissions and increase sinks are not well-quantified. In addition, there is a need to determine the economics behind different practices to better inform future program design. The objective of this review was to provide a synthesis of the science on the efficacy and cost-effectiveness of best management practices (BMPs) at mitigating GHG emissions and increasing sinks from soils, landscapes, climates and production systems relevant to Ontario.