Corn Yield Response to Seeding Rate

• 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.

   

• Sixteen Kruger Seeds™ 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 62.5% (10 out of 16) of the products, yield increased as seeding rate increased such that the highest seeding rate (40,000 seeds/acre) produced the highest yields (e.g. K9701DP brand blend).

• With the remaining products, yields were highest at 35,000 seeds/acre in four products (e.g. K1204SS brand blend) and similar at the 30,000 and 35,000 seeds/acre seeding rates in K0109SS and K0807SS brand blends.

• Yields were lowest at the lowest seeding rate (30,000 seeds/acre) in 81% of the products tested. 

   

• 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. More than 60% (10 out of 16) of the products tested yielded an economic return at the highest seeding rate (e.g. K0518DD brand blend). With the remaining products, three (19%) were economical at 35,000 seeds/acre (e.g. K1611DP brand blend) and three were most economical at 30,000 seeds/acre (e.g. K0807SS brand blend).

• 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.  

• Growers are also advised to consult their trusted agronomists and dealers in selecting the best products for their operation.

¹Nielsen, 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

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