2021
Soybean Yield Response to Planting Populations in Delaware
Contributor/Checkoff:
Category:
Sustainable Production
Keywords:
DiseaseField management Pest
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Jarrod Miller, University of Delaware
Co-Principal Investigators:
Project Code:
PLSC43292521014/PLSCDA2114
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:

Many agronomic practices and standards need periodic evaluation. Evaluations of soybean population across the United States observe that lower populations do not necessarily result in lower yield. While Delaware results may be like those of other regions, this climate and soil types will still have an interaction with plant population. This study observed yield results from five different planting populations between 60,000 and 180,000 seeds per acre for full-season and double-crop soybeans. Additional treatments were added to include 15- and 30-inch row spacing, as well as irrigation and rainfed plots. Statistical analysis of results evaluates yield response to planting populations and other practices.

Key Benefactors:
farmers, agronomists, Extension agents

Information And Results
Project Deliverables

Results will be shared through the Delaware Agronomy Blog and reported to the Delaware Soybean Board.

Final Project Results

Updated December 3, 2023:
Many agronomic practices and standards need periodic evaluation. Soybean population studies are being evaluated across the United States and observing that lower populations do not necessarily result in lower yield. While Delaware results may be like those of other regions, our climate and soil types will still have an interaction with plant population. This study observed yield results from 5 different planting populations between 60-180,000 seeds per acre. Additional treatments were added to include row spacing (15 and 30”) as well as plots that were irrigated and rainfed at our variable rate irrigation research farm in Harbeson, DE. Plots were planted in May 2022 and harvested with a plot combine in November 2022.

For the 2022 dataset, there was no difference in populations (maturity group 4.3) for full season soybeans ranging from 60-180,000 seeds per acre. Yields ranged from 62-68 bushels per acre based on populations averaged across row spacing and irrigation status. This certainly gives flexibility for Delaware farmers in lowering seeding rates in an era of higher costs. However, this represents one year at one site, and local on-farm seeding rates should be performed by each producer. Row spacing remains best for full season soybeans at 15 inches, with a 10 bushel advantage. This was only based on one variety, however this matches most nationwide research.

Irrigation remains one of the best methods for Delaware farmers to remain competitive for higher soybean yields, providing a 25-bushel advantage averaged across all row spacings and populations. The interesting observation from this study is that there was no interaction with population, so lower populations on rainfed and irrigated fields have similar differences to higher populations under the same scenarios. This type of work should be performed annually to keep up with varying weather conditions.

View uploaded report PDF file

Many agronomic practices and standards need periodic evaluation. Soybean population studies are being evaluated across the United States and observing that lower populations do not necessarily result in lower yield. While Delaware results may be like those of other regions, our climate and soil types will still have an interaction with plant population. This study observed yield results from 5 different planting populations between 60-180,000 seeds per acre. Additional treatments were added to include row spacing (15 and 30”) as well as plots that were irrigated and rainfed at our variable rate irrigation research farm in Harbeson, DE. Plots were planted in May 2022 and harvested with a plot combine in November 2022.

For the 2022 dataset, there was no difference in populations (maturity group 4.3) for full season soybeans ranging from 60-180,000 seeds per acre. Yields ranged from 62-68 bushels per acre based on populations averaged across row spacing and irrigation status. This certainly gives flexibility for Delaware farmers in lowering seeding rates in an era of higher costs. However, this represents one year at one site, and local on-farm seeding rates should be performed by each producer. Row spacing remains best for full season soybeans at 15 inches, with a 10 bushel advantage. This was only based on one variety, however this matches most nationwide research.

Irrigation remains one of the best methods for Delaware farmers to remain competitive for higher soybean yields, providing a 25-bushel advantage averaged across all row spacings and populations. The interesting observation from this study is that there was no interaction with population, so lower populations on rainfed and irrigated fields have similar differences to higher populations under the same scenarios. This type of work should be performed annually to keep up with varying weather conditions.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.