Annual soybean yields have increased nationwide and in Illinois by 10.9 and 13.6 kg haˉ¹
yearˉ¹respectively, over the last 15 years (USDA NASS). This increase has come from a
combination of genetic improvements, the introduction of biotechnology, and improved cultural practices. Selective breeding has also improved grain composition, increased pest tolerance, and increased yield potential. The utilization of newer biotechnology techniques has also allowed soybean breeders to insert traits into soybean germplasm. This has subsequently simplified weed management for soybean growers. While the yield potential of soybean is genetically determined, achieving full yield potential also requires an optimum environment. Therefore, a soybean grower’s best opportunity to maximize yield is proper cultivar selection, and the maintenance of adequate fertility and other environmental conditions to the best of their ability. Ever since soybean has been a major crop, there has been ongoing research to determine that optimum environment. In general, aside from cultivar selection and adequate fertility, manipulation of soybean planting date, seeding rate, row spacing, and weed control are
major agronomic factors that are routinely studied as they can significantly influence yield potential and economic return. This research considers previous efforts and advances our understanding of the process between competing plants with in a soybean canopy.