Selecting a Hybrid and Seeding Rates
Selecting a Hybrid
The next step is selecting the proper corn hybrid for the field, taking into account the range of possible growing conditions and resulting yield potential of field areas. Your local Pioneer sales professional is a valuable resource to help identify the right product for your growing environment.
Selecting Seeding Rates
Corteva Agriscience researchers conduct thousands of field research trials at hundreds of locations annually across North America to help understand grain yield response to planting rate for Pioneer® brand hybrids. In addition, many growers have their own data on variable planting rates gathered from as-planted and yield data. Decades of Corteva Agriscience research have shown that corn yield response to seeding rate within a commercially relevant range can usually be well-described by a quadratic function. Grain yield will increase with seeding rate up to an optimum point and then decline as seeding rate is increased above the optimum due to a higher rate of barrenness and extended anthesis-silking intervals (Jeschke et al., 2009). The optimum seeding rate can vary based on hybrid genetics. Figure 2 shows an example of quadratic response functions for two hybrid families with the same CRM that have been shown to differ in their response to plant population in Corteva Agriscience research trials.
Figure 2. Economic optimum planting rates of two Pioneer brand hybrid families with similar comparative relative maturity at a 250 bu/acre yield level.
Seeding Rate Response to Productivity
Yield response to seeding rate by productivity level is the critical factor for creating variable-rate seeding prescriptions. The population required to maximize yield increases as yield level increases. When grouped by yield level, results from Corteva Agriscience plant population trials showed that the economic optimum seeding rate increased from approximately 31,000 seeds/acre at the 150 bu/acre yield level to over 39,000 seeds/acre at the 240 bu/acre yield level (Figure 3). An Iowa State University study comparing corn yield response to plant population across soils with different corn suitability ratings found similar results. The most productive soils tended to have a higher optimum population for maximum yield (Woli et al., 2014).
Figure 3. Corn grain yield response to seeding rate at nine yield levels, average of all hybrids tested over a six-year period. Dots indicate the economic optimum seeding rate within each yield level.
The increase in optimum seeding rate by yield level has been shown to be roughly linear within the range represented by research data (Figure 3).
Economic and Agronomic Optimum Rates
It is important to note that suggested seeding rates produced via the Pioneer Planting Rate Estimator and Granular Variable Rate Seeding Tools are based on economic optimum rates that consider both the revenue from yield and the cost of additional seed. This provides the most useful information for optimizing return on seed investment. When comparing recommendations from different companies, farmers need to understand the economic and genetic assumptions that affect each recommendation.