Nkoa, R., Kendall, K. and Deen, W. 2014. Ecozone dynamics of crop residue biomass, macronutrient removals, replacement costs, and bioenergy potential in corn-soybean-winter wheat cropping systems in southern Ontario. Can. J. Plant Sci. 94: 981-993. In light of frequent price hikes of imported fuels and the everlasting growth in the world's crude oil consumption, producing energy from renewable, non-fossil sources, such as crop residues and dedicated energy crops, has gained an unprecedented attraction across developed countries. This study aimed at assessing the dynamics of crop residues biomass, NPK removals, bioenergy potentials, in southern Ontario. Two surveys were carried out across 20 counties, and data were analyzed using one-way classification random and three-way crossed classification mixed effects models, respectively. Corn stover was estimated at 7.5 t ha^-1 yr^-1, equivalent to 139.7×10⁹ J ha^-1 yr^-1, and NPK-removal rates of 53, 4, and 62 kg ha^-1, respectively. For wheat, the straw biomass was estimated at 4.3 t ha^-1 yr^-1, equivalent to 79.4×10⁹ J ha^-1 yr^-1, and NPK removal rates of 28, 3, and 35 kg ha^-1, respectively. Soybean straw biomass was estimated at 3.1 t ha^-1 yr^-1, equivalent to 24.76×10⁹ J ha^-1 yr^-1, and NPK-removal rates of 33, 5, and 35 kg ha^-1, respectively. Overall, cutting corn and winter wheat stalks at ground level rather than at 15 cm above ground yielded higher residue biomasses, which did not statistically translate into higher NPK removal rates due to lower NPK concentrations in the stubbles.