Soybean Yield and Profit Potential According to Seeding Rates in Limited Irrigation
February 3, 2025
TRIAL OBJECTIVE
- Growers are looking to reduce input costs by reducing soybean seeding rates while still obtaining profitable yields.
- The objective of this trial was to evaluate the effects of soybean seeding rate on yield and revenue when produced under limited irrigation.
RESEARCH SITE DETAILS
- The trial was arranged as a randomized complete block design with four replications and one treatment factor:
- Soybean seeding rate
- 80,000 seeds/acre
- 100,000 seeds/acre
- 120,000 seeds/acre
- Soybean seeding rate
- Field operations, cover crop seeding rate and planting time, fertilizer, herbicide, irrigation, and precipitation information are listed in Table 1.
- Total seed weight, test weight, and moisture content were collected with a plot combine and yield per acre was calculated later.
- Statistical analysis was performed using Fisher’s Least Significant Difference (LSD).
UNDERSTANDING THE RESULTS
Soybean Grain Yield
- Soybean yields from plots planted at 120,000 seeds/acre were greater than yields from plots planted at either 100,000 or 80,000 seeds/acre.
- The plots planted at the 120,000 seeding rate yielded 3.3 and 3.9 bushels/acre more than the plots planted at the 100,000 and 80,000 seeding rates, respectively.
- There was no significant difference in grain yield between the 100,000 and 80,000 seeds/acre seeding rates.
- Soybean final stand count was at least 24.8% lower than the target seeding rate. As the seeding rate increased, the percent reduction in final stand count also increased (Table 2).
- Lower seeding rates (80,000 and 100,000 seeds/acre) resulted in higher yields per thousand seeds compared to the 120,000 seeds/acre rate. However, the 120,000 seeds/acre rate resulted in a higher yield per area, or bu/acre (Figure 1 and Table 2).
- Based on an average seed cost of $68/unit (1 unit = 140,000 seeds), the cost of each seeding rate, and a $10.00/bu cash price, the 120,000 seeds/acre rate resulted in $29 more profit per acre than planting at 100,000 seeds/acre, and $13 per acre more than the 80,000 seeds/acre rate (Table 3).
KEY LEARNINGS
- Soybean plants compete with each other in the seed row. This trial found evidence of competition at all seeding rates based on the final population stands. Thus, it is imperative to consider competition when planning seeding rates.
- Even though the yield per thousand seed was higher in lower populations, that did not translate to a higher yield per acre. In fact, the highest yield and profitability was found with the highest tested seeding rate (120,000 seeds/acre).
- Previous research from the Gothenburg Learning Center showed that higher soybean seeding rates planted into wet soil conditions improved grain yield. However, in this trial, the lower 80,000 seeds/acre rate generated more profit per acre than the 100,000 rate, so a higher rate may not always provide insurance for a higher profit margin.
- Soybean product selection and seeding rate performance can vary according to location. Please contact your local Bayer seed provider for local recommendations.
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Always read and follow pesticide label directions, insect resistance management requirements (where applicable), and grain marketing and all other stewardship practices.
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