By Benjamin Agyei
Key Points
- Developed an optimal hybrid relative maturity (RM) map under typical corn planting times in Michigan.
- Hybrid RM that maximized profits was typically lower than the RM that maximized yield for most Michigan locations.
- The RM that maximized yield and profits changes based on planting date.
- If corn is planted early (late April to early May in south central Michigan), use RMs that are 5–10 units greater than what is usually planted.
- If corn is planted in late May, use the baseline RM recommendations to ensure corn has enough time to dry down.
- For plantings in June, use RMs that are around 5 units lower than what is usually planted.
- For growers in northern locations, use lower end of our recommendations for adjusting RM based on planting date.
- Kernel weight does not change after black layer is formed, so corn can be left in the field for additional dry down if needed, but extended field drying can increase risk of harvest losses.
Introduction
Corn is widely grown in Michigan and other northern states because soils in this region are naturally fertile, with high organic matter and water holding capacity. Seasonal precipitation average is also about 30 inches, which is generally considered sufficient given that corn typically requires about 22 to 30 inches of water from planting until physiological maturity.
In recent years, a lot of weather-related changes have occurred in this region. One example is the expansion in the frost-free season length due to the later occurrence of the first fall frost and the earlier occurrence of the last spring frost. For Michigan corn growers, this observation is important as it presents a unique opportunity to make strategic agronomic changes.
While changes in weather have created new opportunities, they have also created additional challenges. The frequency and intensity of severe storms have increased in recent years. Most of these extreme storms occur in the spring; hence, they often leave fields flooded for several days, forcing growers to delay planting. In fact, the number of workable field days has decreased in some locations due to these wet conditions. A recent example was the 2019 growing season, where many acres were planted more than a month later, while several others were left unplanted.
Growers are also dealing with significant market shocks in recent years. While corn prices have declined, input costs continue to rise. It has therefore become more critical than ever for growers to understand how to effectively use the growing season length to maximize yield and profitability.
Planting date and hybrid relative maturity (RM) are the two most important management decisions that impact yield and profits. There is limited control over when corn can be planted because it depends on field conditions. Additionally, planting into non-ideal conditions (cold and wet) is not recommended as corn is less forgiving than soybeans (Singh et al., 2026).
Source : msu.edu