- A critical agronomic decision is the choice of soybean products and their associated optimum seeding rate. Though soybeans compensate well at different plant populations, soybean products respond differently and the search for the optimum seeding rate continues.
- The objective of this study was to determine the yield potential of soybean products at different seeding rates.
Research Site Details
- Fourteen Kruger Seeds™ brand soybean products ranging from 1.8 to 3.3 maturity group (MG) were planted at 100,000, 140,000, and 180,000 seeds/acre.
- The trial was planted in 30-inch spacing, 4 rows per product per seeding rate, and 200-ft long plots.
- Weed management consisted of a rye burndown with Roundup PowerMAX® herbicide and a post-emergence application of XtendiMax® herbicide with VaporGrip® Technology, Warrant® herbicide, and Roundup PowerMAX®.
Understanding the Results
- The decrease in plant population across the trial between the V4 and R8 growth stages was partly due to wet and rainy conditions at the research site in May and June, followed by a dry July. Such conditions result in poor seedling health and reduced crop stands.
- The seeding rate did not have an impact on lodging in most of the soybean products tested (Table 1 and 2). However, there were a few products where lodging increased with increased seeding rate (e.g. K2X-2172).
- In both the early and late MGs, yield increased as seeding rate increased, except for K2X-1862 and K2X-3353 in which the median seeding rate produced the highest yields.
- In the products in which yield increased with seeding rate, the biggest yield increase was from the 100,000 to 140,000 seeds/acre rate increase (Figure 1 and 2).
What Does This Mean for Your Farm?
- With the current soybean seed cost at $62/bag and soybean grain sold at $7.50/bu, a minimum of a 2.4 bu/acre yield increase is needed to justify a 40,000 seeds/acre seeding rate increase.
- Thus, in the early MG, 180,000 seeds/acre was both the highest yielding and most profitable seeding rate for most products in this trial. For the others, 140,000 seeds/acre was the optimum seeding rate (Figure 1).
- 180,000 seeds/acre was the highest yielding and the most profitable seeding rate for all but one product (K2X-3353) in the late MG (Figure 2).
- This is our fourth year of research into germplasm response to seeding rate. Results from the 2015-2017 trials were product-specific and did not provide a consistent trend in response to seeding rate1. The 2018 results are consistent across almost all products tested, providing a good benchmark for future decision making.
- Growers should consult their trusted agronomists and dealers in choosing the best products for their operation.
1Monsanto Learning Center at Huxley, Iowa Demonstration Reports, 2015-017.