• Research has indicated that corn yield has a positive correlation with seeding rate until a threshold is reached. Further increases beyond this threshold negatively impacts yield and/or economic return for the product.^1,2 Defining the seeding rate threshold for a corn product is difficult as it’s highly affected by management practices and the environmental conditions during the growing season.

• However, knowing this threshold is critical as it forms the basis upon which other management practices are based.

• The objective of this trial was to evaluate the yield potential and standability of DEKALB® corn products to seeding rate.

• All weed control, insect control, and irrigation inputs were applied per local standards.
• Eight DEKALB® corn products were planted on bedded single rows with 38-inch row spacing at 17,500, 22,500, 27,500, 32,500, 37,500, and 42,500 seeds/acre. 
  • DKC65-95 brand, VT Double PRO® Technology
  • DKC65-99 brand, Trecepta® Technology
  • DKC66-18 brand, VT Double PRO® Technology
  • DKC67-37 brand, SmartStax® Technology
  • DKC67-44 brand, VT Double PRO® Technology
  • DKC67-94 brand, Trecepta® Technology
  • DKC69-99 brand, Trecepta® Technology
  • DKC70-27 brand, VT Double PRO® Technology
• 240 lb of nitrogen was applied as 32% liquid UAN.
• The trial was conducted as a single replicate strip plot and each plot was approximately 0.6 acre.  
• All data was collected using Precision Planting® 20/20 SeedSense® via Climate Fieldview™ Platform. Yields were corrected to 15.5% in the analysis.

• Not all products in this demonstration responded the same to seeding rate in either yield or standability. Individual product response to increasing seeding rate varied across corn products but followed an upward trend in average yield (Figure 1). Generally, corn seeding rates are most favorable in the 33,000 to 38,000 range for most of the tested products in this demonstration.
  • Across all corn products, the return on investment (ROI) for a 10,000 seeds/acre increase in seeding rate was $10.54/acre (Table 1).
  • Of the eight products tested, six of them responded favorably to higher seeding rates with a range of $9.00 to$56.00/acre for a 10,000 seeds/acre increase in seeding rate (Table 1).
  • The average ROI for these six products was $20.42/acre over seed costs (Table 1).
  • The remaining two products showed either lodging issues or little yield response to increasing seeding rate. This led to a negative average ROI of -$19.10/acre for greatly increasing seeding rate (Table 1).
  • It is important to note that while these returns on investment are from one season of data, the average yield results based on seeding rate are similar to other SLC research in previous years.

• Knowing the optimal seeding rate of a corn product can help maximize yield potential. 

• Our observations at SLC showed that corn products can and do respond favorably to higher seeding rates. However, high plant populations can result in lodging and exacerbate harvest difficulties. Conversely, full yield potential may not be realized with lower than optimal seeding rates. 

• Growers should carefully evaluate each new corn product planted for its response to population in both standability and yield with multiple years and locations used for reference. 

• Seeding rate should be adjusted based on field yield potential levels and soil types, as well as the potential return on investment. 

• The cost of seed corn is one of the largest variable input costs for most corn growers.³ Minimizing that cost includes wise selection of seeding rates. This research can help growers evaluate DEKALB corn product seeding rates for their operations. 

• Contact your local Field Sales Representative or Technical Agronomist for planting recommendations for the current situation and year.  

Sources: 

¹Fromme, D.D., Spivey, T.A., and Grichar W.J. 2019. Agronomic response of corn (Zea mays L.) hybrids to plant populations. International Journal of Agronomy. Vol 2019. https://doi.org/10.1155/2019/3589768.  

²Nielsen, R.L., Camberato, J., and Lee, J. 2019. Yield response of corn to plant population in Indiana. Agronomy Department. Purdue University. http://agry.purdue.edu.  

³Langemeir, M.R., Dobbins, C.L., Nielsen, R.L., Vyn, T.J., Casteel, S., Johnson, B. 2019. Purdue crop cost and return guide. Purdue Extension. ID-166-W. http://ag.purdue.edu.  

Websites verified 09/29/2020.  3013_R1_20