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Developing Infrastructure for Implementing Adaptive Management Practices for Corn on a Large Scale in

Iowa

Tracy BlackmerPeter Kyveryga

www.isafarmnet.comAdvancing Agricultural Performance®

Iowa Soybean Association On-Farm Network®

Precision Ag Tools

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The high price of nitrogen fertilizer/grain combined with the complexity of N dynamics makes it desirable to improve N management.

2008 Aerial Image

Precision Ag Tools

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2008 Aerial Image

Precision Ag Tools

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Started as a variable rate project to identify areas needing more or less N.

The results were such that improvements are needed at a whole field level before we target a subfield level.

Precision Ag Tools

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Precision ag tools help collect an unprecedented amount of data.

Replicated Strip Trials

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Replicated strip trial example.

N-50 refers to “normal” rate and 50 lbs N/a less.

Replicated Strip Trial Report

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Replicated strip trial example.

Page 1 Aerial image

Replicated Strip Trial Report

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Replicated strip trial example.

Page 2 Grain yield map

Replicated Strip Trial Report

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Replicated strip trial example.

Page 3 Treatment position map

Replicated Strip Trial Report

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Replicated strip trial example.

Page 4 Summary statistics

Fertilizer N Grain Yield

--------lb N/acre-------- -----------------bu/acre-------------------

2001 C-SB 80 130 176.8 175.6 -1.2 

2002 C-SB 70 120 192.5 195.4 2.9 

2003 C-C 130 180 166.6 166.2 -0.4 

2004 C-SB 60 110 199.7 206.1 6.4C-C 110 160 172.0 178.3 6.3

2005 C-SB 60 110 191.8 197.6 5.8C-C 110 160 182.1 193.9 11.9

2006C-C 120 150 188.4 192.5 4.12007 C-C 125 150 177.1 182.1 5.0

 

Year Rotation Low Rate High Rate Low Rate High Rate Diff.

 

Case Study: Grower Evaluation

Additional Analysis

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Yield increase from an additional 50 lbs N/a as affected by rainfall

Rainfall has a big impact on N management.

This should be factored into the evaluations. y=-6.02+1.22 x,

r2=0.52

Cummulative spring rainfall, in

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cre

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Nitrogen Evaluations

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# Guided Stalk Sampling# Replicated Strip Trials# Scouting Network# Watershed Programming

Over 1,000 guided stalk sample fields.

Over 150 N replicated strip trials.

End of Season Stalk Nitrate Test

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Stalk samples collected from 6-14 inches above ground after physiological maturity.

End of Season Stalk Nitrate Test

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Stalk samples collected from 6-14 inches above ground after physiological maturity.

Replicated Strip Trials

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Data collectedAerial ImageryGrain yieldStalk nitrate

Stalk Testing the Strip Tests

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Calibration data is consistent with recommendations.

Guided Stalk Sampling

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How do you represent this field?

Guided Stalk Sampling

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Four stalk nitrate samples

Three by soil map units

One sample based on image “deficiency”

Additional Analysis

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N

© 2007 Iowa Soybean Association

Stalk Nitrate Levels(By Category)

#0 Low (< 250 ppm)

Marginal (250 - 700 ppm)

Optimum (700 - 2,000 ppm)

High (> 2,000 ppm)

#0

#0

#0

Soil Survey138B

GSS2007_475

TM

AdvancingAgricultural Performance

#0

#0

#0

#069

2058

13991170

162B

162C

163E3163C

163D2

162C

163B

163E3

2007 Stalk Nitrate Samples

0 300 600 900 1200 1500 1800 2100 Feet

Trial Results

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Statewide Analysis

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The distribution of stalk nitrate samples across Iowa in 2007

DeficientMarginal

Optimal

Excess

Applying adaptive management results in feedback data. One outcome is a “benchmark”

The benchmark can:

• provide a status of management to the public• track impact of programming• Impact regulations

Guided Stalk Sampling

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The benefit is multiplied by focusing on results in a group – not just an individual.

Group Results

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Guided Stalk Sampling Group

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Summary of stalk nitrate samples

Management practice

Sam

ple

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tag

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Differences between management practices are often observed at a group level.

Statewide Analysis

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The distribution of N forms is fairly well distributed.

For Additional Results

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