Managing the continuous corn yield penalty with crop and residue management

Corn (Zea mays L.) grown in rotation with soybean [Glycine max (L.) Merr.] generally yields more than corn grown continuously, with the latter designated the continuous corn yield penalty (CCYP). Due to global food security concerns and corn’s versatility in food products, animal feed, and biofuel/bioenergy feedstocks, production of corn must increase with the projected increasing world population. As a result, yield per area or the area in corn production must increase, which could result in more corn following corn acres. Primary causative factors contributing to the CCYP are soil nitrogen availability, residue accumulation, and the weather. Therefore, the objective of this research was to evaluate and determine management practices that could help relieve the yield penalty associated with production of continuous corn compared to when rotated with soybean. This research encompasses two research areas: What are the effects of hybrid selection, enhanced fertility, and population on corn yield and can these factors reduce the CCYP? Enhanced fertility improved grain yield across rotations and there was a 40 to 60% greater yield response to intensive management in continuous corn versus the corn-soybean rotation, suggesting intensified management as a method to mitigate the CCYP. With select hybrids, intensive management reduced the CCYP by 30 to 80%. Yield advantages to corn rotated with soybean were achieved through both more numerous and heavier kernels. Agronomic management and hybrid selection helped alleviate the CCYP demonstrating continuous corn can be managed for better productivity. Can the CCYP be alleviated by mechanical and chemical residue management in combination with an intensive agronomic input system? As grain yield level increased, stover biomass production increased, resulting in additional residue to be managed post-harvest, reinforcing the need to manage crop residue in not only continuous corn but also in high grain yield environments. Sizing down the stover material at harvest improved overwinter residue decomposition. Stress induced by continuous corn was not detected through crop assessments until the R2 reproductive stage. Intensive inputs resulted in additional early season above- and below-ground biomass compared to standard inputs and increased grain yield. Crop rotation, downsized residue, high input agronomic management, and hybrid selection all enhanced final grain yield