A recent study from DuPont Pioneer outlined the continuous-corn yield penalty, and the causes for that penalty. Over a six-year period, the study found that continuous corn yields, on average, 25 bushels per acre fewer than corn that follows soybeans.
The key culprit? Lack of nitrogen availability in the soil. In fact, limited nitrogen accounts for 85 percent of the continuous-corn yield penalty, with the number of years of corn planted and weather rounding out the top three causes. The study found that an average of an additional 10 pounds of nitrogen per acre was needed to achieve optimum yield results; however, those optimum yield results were still lower than corn following soybeans.
That’s not to say continuous-corn systems can’t be managed well. The DuPont Pioneer study found that highly productive soils, combined with a strong focus on residue management, are the keys to minimizing the yield penalty. Continuous corn allows for a buildup of residue over time, leading to pest and disease vulnerabilities, lower soil temperatures and less moisture, and lower rates of nitrogen mineralization.
Intensely managing the soil nutrition in a continuous-corn system is critical. Granular fertilizers that release nutrients over time help maintain nutrient availability throughout the growing season. Premium fertilizers, such as MicroEssentials® and Aspire™, combine major fertilizer components (such as N, P and K) with micronutrients. Using these premium products and managing corn residue will help reduce the yield penalty in continuous-corn systems.