Agriculture is a large source of greenhouse gas (GHG) emissions but changing management practices to those more beneficial to the environment could help mitigate climate change as long as they are economically and environmentally viable. This study examines the environmental (public) and economic (private) effects of adopting ten different beneficial management practices on a representative corn farm in Ontario, Canada. The study integrates changes in GHG emissions in carbon equivalents (CO2e) and changes in profit from changes in costs and revenues in two dimensions to reveal the scope and scale of different kinds of practices. 4R nitrogen management practices are smaller in scale compared to cropping practices and, therefore, have smaller potential costs and benefits. Land use changes, from practices including biomass, afforestation, crop rotation and cover cropping, have larger impacts on soil sequestration and carbon-equivalent GHG reduction, but with significantly greater costs. Seven practices were found to, at least partially, be economically and environmentally beneficial. The adoption of no-till and N-rate reduction is firmly positive, whereas the production of biomass has the largest potential economic and environmental gains. Crop rotation and diversification and cover cropping can be mutually beneficial, as can changing N-application practices. The use of inhibitors may be economically beneficial if yield gains outweigh purchase costs.