In general, corn yield potential has continued to improve in the United States. Research has shown that corn yield has a positive correlation with planting density until a threshold is reached, beyond which yield decreases.1 Defining the optimal density threshold for each corn product is difficult as it’s highly affected by management practices and the environmental conditions during the growing season.
Understanding the threshold is critical as it forms the basis for management decisions, such as nitrogen rate. The objective of this trial was to determine the optimum yield response of corn products to different seeding rates.
Thirteen DEKALB® corn brand blends were selected to represent the northeast, northwest, central, southeast, and southwest growing regions of Iowa. Products were planted at 30,000, 35,000, and 40,000 seeds/acre.
Tillage, weed control, and nitrogen management were the same for all products at the respective locations.
The trial was conducted in 30-inch row spacing, with 10-ft x 30-ft plots per product and seeding rate at various replications based on the product (Figure 1).
In 54% (7 out of 13) of the products, yield increased as seeding rate increased with the highest seeding rate (40,000 seeds/acre) having the highest yields.
With the remaining products, yields were similar between the 35,000 and 40,000 seeds/acre seeding rates in three products (e.g. DKC58-34RIB brand blend), whereas yields decreased in the other three products (e.g. DKC63-90RIB brand blend) above the 35,000 seeds/acre seeding rate.
Yields were lowest at the lowest seeding rate (30,000 seeds/acre) in all products except for DKC55-33RIB brand blend for this trial.
Several factors should be considered when selecting the seeding rate for a corn product. Key among these factors are plant standability, nitrogen fertility, and economic feasibility.
In the current market environment, a 5 bu/acre yield increase is required for every 5,000 seeds/acre increase in seeding rate. Only 38% (5 out of 13) of the products tested produced an economic yield at the highest seeding rate (e.g. DKC50-08RIB and DKC61-98RIB brand blends).
Crop yield response to operation inputs can be highly variable, often substantially impacted by the environmental conditions during the growing season. Growers should consider testing new products and concepts on a small scale on their farm to see how it fits in their operation.
Bayer Crop Science uses an innovative planter technology called the Genetic Environment Narrative (GEN) planter to characterize corn product performance by evaluating yield response to plant density across different environments. The GEN planter provides the ability to simultaneously plant multiple corn products and quickly and accurately change planting populations as it moves across a field. These unique planting capabilities generate over one hundred thousand detailed yield observations each season across diverse growing conditions. This provides data to optimize product management recommendations for key corn growing regions in the United States. Please visit the population optimizer tool at https://www.dekalbasgrowdeltapine.com/en-us/dekalb/tools/optimize-my-seed.html for plant density recommendations for your region.
Growers are also advised to consult their trusted agronomists and dealers in selecting the best products for their operation.
Nielsen, R.L. 2013. Thoughts about seeding rate for corn. Department of Agronomy, Purdue University. https://www.agry.purdue.edu/ext/corn/news/timeless/SeedingRateThoughts.html