Soybeans for Improved Soil Health: Determination of Lower than Predicted Contribution of Pulse Crop Residues to Greenhouse Gas Emissions and Improved N Uptake and Yield of following Wheat and Corn

The primary goal of this research is to gain a better understanding of the beneficial role that soybean has in improving the nutrient-use efficiency, soil health, and environmental footprint of cropping systems in Manitoba. Using a field study we will provide the information necessary to correct the estimate of contribution of legume crop residues such as soybean to N₂O emissions. Current contributions we expect are too high and overestimate the environmental footprint of soybean. The field study will also provide further determinations of the amount of BNF by soybean in Manitoba. Lastly, the study will provide further determinations of the contribution of soybean to N uptake of spring wheat and grain corn. A stable isotope labelling (15N) approach will be used to track soybean N for contributions of residue N2O emissions, BNF and N credit to following crops. The study is paired with one in Saskatchewan in which similar questions are asked but with lentil, pea and chickpea as the pulse crops. This study is four years in duration to provide two cycles of soybean-spring wheat/corn cropping and determinations.