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MULTI-YEAR REPLICATED SOYBEAN HIGH YIELD INPUT STUDY

BY Dairyland Seed Agronomy Team
Introduction

Typically, 60-75 percent of soybean flowers and/or pods abort in response to soybean plant stressors.  Stress may be imposed on a soybean plant from poor weather, herbicides, insects, inadequate fertility, compaction, drainage, disease, inappropriate population/row width, poor sunlight quality etc.  The objective is to discover reasonable, consistent agronomic practices that will reduce soybean plant stress, therefore improving flower and pod retention and increase seed size which should translate into improved soybean yield.

This project will focus primarily on suppressing disease and insect pressure at critical growth stages for soybeans (R1-R6).  Disease is considered to be the #1 stressor for soybeans in the Eastern Corn Belt.

Disease and insects will be managed through genetics, seed treatment and foliar applied fungicide/insecticide at critical growth stages.

This study was conducted for four years at the Dairyland Research Farm, Wabash, Indiana.

Methods: 2020 Crop Year
  • DSR-3587E treated with Lumigen Soybean seed treatment with high rate Ilevo
  • 15” rows @150,000, 4 replications, 6 Treatments, Planted May 3, 2020
  • Glyphosate + Mn EDTA by R2 will be applied to entire plot and used as a check.
Treatments:  2020
  1. Check (Glyphosate + Mn EDTA)
  2. 60# N (R3)
  3. Aproach Prima & Cobalt  (R2), (Fungicide & Insecticide)
  4. Aproach Prima & Cobalt (R4), (Fungicide & Insecticide)
  5. Treatment 3 & 4 (combined)
  6. Treatment 5 & 2 (Combined)
2020 Results, 4 Reps     

Treatment

Average Yield All Reps

1

64.16

2

64.31 (+.15)

3

61.98

4

63.20

5

67.58 (+3.42)

6

65.94 (+1.78)

            
Statistical analysis 2020, LSD (0.10) =2.98 For Treatment #5  
Methods: 2018 Crop Year
  • DSR-3434R2 Treated
  • 15” rows
  • Planted 5/10/18 @ 160,000
Treatments: 2018
  • Check
  • Thio-sul 4 gal. 3x2
  • 60# N at R2
  • Priaxor (fungicide) R2
  • Cobalt (insecticide) R2
  • Priaxor (fungicide) R4
  • Cobalt (insecticide) R4
  • All above treatments combined

2018 Results, 4 Reps 

Treatment

Average Yield All Reps

1 Check

80.1

2

78.08

3

82.82 (+2.72)

4

78.37

5

79.31

6

86.18 (+6.08)

7

78.16

8

88.43 (+8.33)

Methods: 2017 Crop Year
  • 365R2 Treated
  • 15” rows
  • Planted 4/22/2018 @ 160,000
Treatments: 2017
  • Check
  • 40# N @ R2
  • Priaxor (fungicide) @ R2
  • Cobalt (Insecticide) @ R2
  • Priaxor (fungicide) @ R4
  • Cobalt (insecticide) @ R4
  • All treatments combined
2017 Results, 3 Reps

No response to inputs!

Treatment

Average Yield All Reps

1 Check

66.24

2

62.94

3

62.94

4

64.90

5

63.75

6

63.63

7

63.39


Methods: 2016 Crop Year
  • DSR-3250
  • 15” rows
  • Planted @ 160,000

Treatments: 2016
  • Check
  • Manganese EDTA @ R1
  • Cobra (herbicide) @ R1
  • 40# N @ R2
  • Stratego (fungicide) @ R2
  • Cobalt (insecticide) @ R2
  • Stratego (fungicide) @ R4
  • Cobalt (insecticide) @ R4
  • 300# N Plus all of the above treatments

2016 Results, 5 Reps 

Treatments

Average Yield All Reps

1 Check

77.06

2

76.74

3

73.75

4

81.49 (+4.43)

5

74.16

6

81.20 (+4.14)

7

76.13

8

75.43

9

79.20 (+2.14)

                                                                                                                    
Summary

There is a slight positive yield trend with this multi-year data toward an R2 application of nitrogen in 2016, 2018 and 2020. Each had wet environments prior to R2 growth stage.  The positive yield gain with a R2 application of nitrogen seemingly occurs in years with an early wet period prior to the R2 growth stage.  Soybeans exposed to an early wet period often have reduced and compromised root systems.  The root systems may be reduced from a lack of oxygen and/or infection from fungal pathogens.  A common result of a reduced and unhealthy root system includes reduced nitrogen fixing rhizobium nodulation.Soybeans begin maximizing nitrogen intake at growth stage R2-3.  The reasoning behind an R2 application of nitrogen in this research is to supplement the soybeans with a minimal nitrogen rate to supply the needed nitrogen at R2-3, until the nitrogen fixing rhizobium redevelops on newer regenerated healthy roots and provides the needed nitrogen through the end of the growing season.  Healthy, well-nodulated soybeans do not seem to benefit from an R2 application of N.

With 4 years of research there has not been any one treatment that has consistently from year to year shown economic benefit.  In 2017, no treatments showed economic benefit.  However, there is a slight trend for a R2 N application.

In summary, due to the unpredictability of the environment during the growing season it seems unlikely at this time that any one treatment will always give a positive return.  Making wise economic management decisions should be based on historical, current and forecast environmental conditions along with an effective scouting program to detect crop threats early enough to take corrective action.

Brian Weller
Brian Weller
Western Region
507.456.3034
Dan Ritter
Central Region
219.863.0583
Branden Furseth
Northern Region
608.513.4265
Rod King
Eastern Region
574.596.6721
Terry Jones
Eastern Region
419.630.3115
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