Effect of Soybean Seeding Rate and Row Width on Agronomic Characteristics and Yield for June Plantings

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January 18, 2021

Effect of Soybean Seeding Rate and Row Width on Agronomic Characteristics and Yield for June Plantings - 2020 

 

TRIAL OBJECTIVE

  • Agronomists and University specialists typically recommend increasing soybean seeding rates when planting later than normal.1 

  • In late-planted soybean crops, higher seeding rates can increase the efficiency of available sunlight since later plantings have less time to grow vegetatively prior to the beginning of pod production.2 

  • Narrow rows help speed crop canopy development and can reduce weed pressure.3 

 

 

RESEARCH SITE DETAILS

 

  • This trial was conducted at Bayer Crop Science FOCUS sites at Roanoke, Illinois (2019 and 2020) and Newark, Illinois (2019). 

  • Ten maturity group (MG) 2.2 to 2.9 soybean products were planted in June. 

  • Seeding rates included 60,000, 80,000, 100,000, 120,000, 140,000 and 160,000 seeds/acre. 

  • Four replications were planted at each location. 

  • The 2019 growing season was very cool and wet through early June, delaying planting for many growers. Hot and dry conditions were prevalent in July and August, and excessive rainfall returned in September and October. 

  • In 2020, there was sufficient moisture in the early portion of the growing season and drought conditions throughout August and into early September. 

  • All soybean products planted in this trial were treated with the same seed treatment. 

 

UNDERSTANDING THE RESULTS

  • Although the highest average yield was achieved at a seeding rate of 160,000 seeds/acre in 30-inch rows, the most profitable configuration in this study was a seeding rate of 100,000 seeds/acre in 20-inch rows. 

  • The highest return on investment (ROI) occurred at a seeding rate of 160,000 seeds/acre for 30-inch rows and 100,000 seeds/acre for 20-inch rows. 

  • Overall, lodging scores were low; however, standability decreased as seeding rates increased. 

  • Overall, disease prevalence was low; however, incidence increased slightly as seeding rates increased. 

 

 
image Figure 1. Average soybean yield and profitability of ten soybean products (MG 2.2 to 2.9) by seeding rate and row spacing across locations and years.
image Figure 2. Lodging incidence relative to row width and seeding rate for six soybean products (MG 2.2 to 2.8) at Roanoke, IL (2020).
image Figure 3. Average incidence of disease development (visual) by row width and seeding rate for six soybean products (MG 2.2 to 2.8) at Roanoke, IL (2020).

KEY LEARNINGS

  • The results support prior studies:
    • When planting soybean seed in June in 30-inch rows, the average return on investment and yield was highest at 160,000 seeds/acre. Since this was the highest seeding rate in the study, it is possible that higher seeding rates may increase yield.
    • When planting soybean seed in June in 20-inch rows, maximum profitability was obtained by planting at a seeding rate of 100,000 seeds/acre, but yield was maximized at 140,000 seeds/acre.
    • Lodging and disease prevalence are generally less when planting late but become more problematic with increased seeding rates.
 
 
Sources: 

1 De Bruin, J.L. and Pedersen, P. 2008. Soybean seed yield response to planting date and seeding rate in the upper Midwest. Agronomy Journal. Volume 100, Issue 3. 

Ball, R.A., Purcell, L.C., and Vories, E.D. 2000. Optimizing soybean plant population for a short-season production system in the southern USA. Crop Science. Volume 40, Number 3. 

Harder, D.B., Sprague, C.L., and Renner, K.A. 2007. Effect of soybean row width and population on weeds, crop yield, and economic return. Weed Technology. Volume 21, Issue 3. 

 

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JANUARY 29, 2020

Effect of Soybean Seeding Rate and Row Width on Yield in Late Plantings  - 2019

TRIAL OBJECTIVE

 

  • Agronomists and universities typically recommend increased seeding rates when planting soybeans later than normal.1

  • Increased populations in later plantings allow more efficient use of available sunlight since later-planted soybeans have less time to grow vegetatively prior to reproduction.2

  • Narrow-row soybean plantings decrease the time required for the crop to reach canopy closure and can result in lower weed pressure.3

 

RESEARCH SITE DETAILS

  • This trial was conducted at Bayer Crop Science FOCUS sites in Woodford and Kendall Counties, Illinois.

  • Six soybean varieties (ranging from 2.4-2.9 relative maturity) were planted in June.

  • Seeding rates ranged from 60,000 to 160,000 seeds/acre.

  • Two planting configurations were tested, 20-inch and 30-inch rows. 

  • Four replications of this trial were planted at each location.

  • The 2019 growing season was very cool and wet through early June, leading to delayed planting for many growers. Hot and dry conditions were prevalent in July and August, and excessive rainfall returned in September and October.

 

UNDERSTANDING THE RESULTS

 

  • Although the highest yield in this study was achieved at a seeding rate of 160,000 seeds/acre in 30-inch rows, the most profitable configuration was a seeding rate of 100,000 seeds/acre in 20-inch rows.

  • 160,000 seeds/acre were required to receive the highest return on investment (ROI) in 30-inch rows, whereas the highest ROI was achieved at 100,000 seeds/acre in 20-inch rows.

KEY LEARNINGS

 

  • These results support those of previous studies.1,2 When planting soybeans in June in 30-inch row spacing in this study, both ROI and overall yield were highest at a seeding rate of 160,000 seeds/acre.  Since this was the highest seeding rate in the study, it is possible that increasing the seeding rate even higher would continue to improve yield.

  • However, when planting soybeans in June in 20-inch rows in this study, maximum profitability was obtained by planting at a seeding rate of 100,000 seeds/acre, but the highest yields were obtained at a seeding rate of 140,000 seeds/acre.

     

Sources:

1 De Bruin, J.L. and Pedersen, P. 2008. Soybean seed yield response to planting date and seeding rate in the upper Midwest. Agronomy Journal. Volume 100, Issue 3.

2Ball, R.A., Purcell, L.C., and Vories, E.D. 2000. Optimizing soybean plant population for a short-season production system in the southern USA. Crop Science. Volume 40, Number 3.

3Harder, D.B., Sprague, C.L., and Renner, K.A. 2007. Effect of soybean row width and population on weeds, crop yield, and economic return. Weed Technology. Volume 21, Issue 3.

 

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