Soybeans will be planted at the UD Warrington Irrigation Research farm. There will be 5 planting populations between 60-180k seeds per acre separated by 30k between each treatment (60, 90, 120, 150, 180k). For each treatment there will be 5 replications, planted on 15 inch rows in plots 10 feet wide and 100 feet long. Full season soybeans will be plated by Mid-May and double crop soybeans will be plated in late June or early July. Plots will be monitored by a drone throughout the season.

Plots will be harvested in between October to November for both full season and double crop soybeans. The results will be analyzed statistically as a randomized complete block design with two factors (population*planting timing).

1) Plant full and double crop soybeans at five rates between 60-180,000 seeds per acre.
2) Evaluate yield response to planting populations.

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

Updated July 30, 2021:
Soybeans were planted at 60-180k seeds per acre at the Warrington Irrigation research farm in Harrington, DE. Due to additional space available, plots were planted on both 15 and 30 inch rows. Herbicide applications have been made as needed. Plots have been monitored by drone imagery throughout the summer and will be harvested in the late fall.

Updated January 1, 2022:
Soybean plots were harvested in November 2021. Plots have been monitored by drone imagery prior to and after harvest to observe any presence of weeds in the plots. Data has been summarized for winter meetings.

Updated November 16, 2022:
Data from this project is erroneous due to a plot combine error. However, overall patterns at both 15 and 30-inch rows indicate that planting rates of 90-120 k seeds/acre may be sufficient for irrigated full-season beans in Delaware. Past research has shown increased yield with 15-inch rows, and the same absolute values were observed here at every planting population besides 180k seed/acre. This project will be repeated in 2022 to provide more consistent results and recommendations.

View uploaded report

Updated April 6, 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

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

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.

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 similar to those of other regions, our climate and soil types will still have an interaction with plant population. This study will observe yield results from 5 different planting populations between 60-180,000 seeds per acre.