Variable Rate Seeding

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Variable Rate Seeding
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Corn Variable Rate Seeding Suggested Practices
Pioneer, Inc.

• Based on yield experiences in Midwest

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Variable Rate Seeding Tips

• Establish final populations of 28,000 to 32,000
  plants per acre except in areas where expected
  yield levels are consistently below 100 bu./acre.
  
• Look for areas in fields that consistently have
  poor plant survival and consider increasing
  seeding rates in these areas (wet, compacted or
  steeply sloping areas).
• Leave uniform seeding rate strips in fields
  planted with a variable rate seeding plan. Be
  sure to check the yields of side-by-side,
  variable rate and uniform rate strips at harvest.

http//www.pioneer.com/growingpoint/default_en.jsp
Variable Rate Seeding Success Requires Patience
and Practice
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Variable Rate Seeding Tips

• Conduct a "split-planter" comparison of a
  variable versus a uniform seeding rates.
• Modern hybrids are more tolerant of
  higher-than-optimum populations.
• Don't make large changes in your seeding rate
  choices based on one or two years worth of data.
• Keep planters properly maintained and calibrated.

http//www.pioneer.com/growingpoint/default_en.jsp
Variable Rate Seeding Success Requires Patience
and Practice
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Midwest Corn Yield Response
http//www.pioneer.com/usa/agronomy/corn/1106.htm
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2002 IMPACT Variable Rate Seeding Study
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Objectives

• Evaluate the operation of the John Deere SeedStar
  system
• Determine the value of varying seeding rate

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SeedStar Principles

• Map based create using JDMap software
• Hydraulic drive for planter
• Automatic adjustment of seeding rate to match map

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Variable Seeding Justification

• Match plant population to yield potential
• Adjust for stand establishment problems
• Decrease seed cost

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Site Description

• IMPACT Center Brazos Valley near Snook
• Irrigated
• Highly variable soils
• Corn following cotton

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Experimental Design

• Alternating passes of fixed and variable rates to
  facilitate paired comparisons
• Three replications
• Five treatments 4 fixed, 1 varying

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Seeding Rates

• Selected on combination of stand establishment
  and yield potential
• Fixed 25, 28, 31, 34k seed/ac
• Variable 4 above rates assigned by polygon

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Seed Rate Polygons

• Area 1 (25,000) - sandy soil, moderate yield
  potential
• Area 2 (28,000) deep silt, highest yield
  potential
• Area 3 (31,000) clay, moderate yield potential
• Area 4 (34,000) poorly drained clay, past stand
  problems, lower yield potential

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Operational Evaluation
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Seeding Map Creation
Graphic courtesy of John Deere Co.
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Seeding Map Creation

• JDMap expects seeding polygons to be drawn from
  yield maps
• Import limited to digitized NRCS soils data
• To use photo and conductivity, had to trick the
  software

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Field Operation

• Easy to select fixed or map operation
• Limited problem with planter height sensor
  preventing seeding
• Provided map of actual seeding rate for
  comparison to target
• Actual tracked target rate well

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Monitor shows current performance and allows easy
selection of preprogrammed seeding rates.
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Results of Seeding Rate Treatments
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Yield Data Collection

• Weighing trailer for grain weight from each
  treatment
• Yield mapping on combine (typical accuracy lt 3
  error)

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Yield Means Trailer Weight
Yield given as pounds since moisture content for
each load was unknown.
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Yield Means (bu/ac)
Means with the same letter are not significantly
different.
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Treatment Paired Comparisons
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Same Rate Paired Comparisons
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Stand Establishment
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Seed Cost Implications

• Variable rate resulted in 31,258 seed/ac average
• No cost reduction compared to nominal rate of
  31,000 seed/ac

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Conclusions

• Operational
• Software limited by data sources for creating
  seed rate polygons
• Field performance was as expected after initial
  learning

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Conclusions

• Seed rate impact on yield
• Rate polygons did not accurately match yield
  pattern
• In 2002, 25,000 seed/ac was optimum rate

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Conclusions

• Seed rate impact on yield
• Variable rate generally matched target rate in
  each area
• Paired comparisons of adjacent treatments showed
  a wide range with no trend

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Conclusions

• Impact on plant stand
• Increasing seed rate on soils with problem
  history improved population

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Conclusions

• Impact on seed cost
• Variable rate treatment averaged near the nominal
  seed rate. No reduction in seed cost for this
  field.

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Summary

• No value to varying seeding rate based on
  polygons used in 2002
• Evaluation will continue with revisions in
  application plan