A Comparison of Yield Monitors versus Weigh Wagons

for On-Farm Corn Hybrid Evaluation

Corn Breeding 101: A Lesson in Basic Corn Genetics. Tom Bechman September 2014.

Dekalb Area Agricultural Heritage Association, Inc.

grain O vator 8GOV125. Four Star Manufacturing. Lewisburg, Tennessee

Grain Weigh GW-150Par-Kan Company. Silverlake, Indiana

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Hyb

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d B

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d D

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Weigh Wagon Grain Cart Seed Tender

Challenges with Traditional Strip Trials

• Small plot area harvested

• Similar weights measurements

• Wind

• Non representative grain sampling

• Measuring wheel error

• Transcription error

• Growers losing interest

The Yield Book

Product Yield Moisture % Test Weight $ per Acre

Hybrid A 151.3 12.2 59.5 $ 870

Hybrid B 130.1 14.6 59.3 $ 748

Hybrid C 143.3 12.5 57.5 $ 824

Hybrid D 131.4 12.4 58.5 $ 756

Hybrid E 110.3 11.6 56.9 $ 634

The Reality

The actual harvested area for Hybrid A is 0.213 acres

1748 - 1678 = 70 pounds or 1.25 bushels

Product Weight Length Width Yield Moisture % Test Weight

Hybrid A 1748 464 240 151.3 12.2 59.5

Hybrid B 1678 504 240 130.1 14.6 59.3

Hybrid C 1804 504 240 143.3 12.5 57.5

Hybrid D 1652 504 240 131.4 12.4 58.5

Hybrid E 1374 504 240 110.3 11.6 56.9

Hyb

rid

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d B

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d D

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Small Plot Area Harvested

Similar Weight Measurements

Wind

Hyb

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A

Hyb

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B

Hyb

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C

Hyb

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D

Hyb

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E

Hyb

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Non-Representative Grain Sampling

Measuring Wheel Error

Transcription ErrorMeasurement Harvest Report Form Computer

Today’s Farmer

iPad

Combine Operation

Yield Monitor

Auto Steer

Smart Phone

Grain Cart Scale

Tank Camera

Global Positioning System

Yield monitors provide a simpler and accurate method for on farm hybrid evaluation that overcomes existing

challenges with traditional weigh wagon methods.

Hypothesis

Literature Review

• Darr et al. (2011) Distinguishing a 3 to 9 percent difference is possible.

• Risius (2014)A combine yield monitoring system should be able to provide an adequate representation of actual yield of harvested grain.

• There is very limited research completed in this area. There are few studies from the late 1990s and early 2000s; however, these are not current with advances in yield monitor accuracy.

Objectives

• Compare corn hybrid testing using yield monitor versus weigh wagons.

• Statistically analyze the data using the correlation coefficient and regression analysis to determine predictability of yield monitors.

• Determine if a yield monitor matches a weigh wagon in ranking the top yielding 25% of corn hybrids in a plot.

Materials and Methods

• Combine mounted yield monitor technology, weigh wagon, hand held moisture tester, measuring wheel.

• Measure and compare weight, moisture content, and yield.

• Six site years (two plots per year for three years).

• 195 total comparisons.

• Excel analysis for correlation coefficient and regression.

• Compare top 25% of hybrids for yield.

Summary of Trials

Location YearWeigh Method Entries Rows

Length (feet)

Row Space

(inches)Area Harvested per plot (acres)

Wessington 2012 Grain Cart 12 12 2679 30 1.85Woonsocket 2012 Seed Tender 25 8 440 30 0.20Hitchcock 2013 Grain Cart 43 8 1090 30 0.50Wolsey 2013 Seed Tender 52 6 625 30 0.22Hitchcock 2014 Grain Cart 54 8 1080 30 0.50Yale 2014 Grain Cart 9 8 2354 30 1.08

Results and Discussion

Location Year EntriesCorrelation Coefficient Regression Analysis

Wessington 2012 12 0.923 Y=-43.487+(1.030*X)

Woonsocket 2012 25 0.934 Y=39.951+(0.952*X)

Hitchcock 2013 43 0.984 Y=-516.138+(1.142*X)

Wolsey 2013 52 0.972 Y=-304.134+(1.123*X)

Hitchcock 2014 54 0.941 Y=1.855+(1.034*X)

Yale 2014 9 0.982 Y=150.724+(0.965*X)

Weighted Average 195 0.959

Summary Chart of the Correlation Coefficient

and Regression Analysis for Weight

Y =weight from the yield monitor in poundsX = weight from the weigh wagon pounds

Results and Discussion

Location Year EntriesCorrelation Coefficient Regression Analysis

Wessington 2012 12 0.008 Y=11.243+(0.015*X)

Woonsocket 2012 25 0.864 Y=6.399+(0.510*X)

Hitchcock 2013 43 0.948 Y=3.776+(0.782*X)

Wolsey 2013 52 0.957 Y=2.058+(0.761*X)

Hitchcock 2014 54 0.931 Y=5.899+(0.656*X)

Yale 2014 9 0.963 Y=-0.801+(1.116*X)

Weighted Average 195 0.878

Summary Chart of the Correlation Coefficient

and Regression Analysis for Moisture

Y = grain moisture percent from yield monitorX = grain moisture percent from traditional tester (GAC2000 or mini GAC Plus)

Results and Discussion

Location Year EntriesCorrelation Coefficient Regression Analyses

Wessington 2012 12 0.989 Y=4.152+(0.925*X)

Woonsocket 2012 25 0.910 Y=-13.034+(1.029*X)

Hitchcock 2013 43 0.963 Y=-10.034+(1.130*X)

Wolsey 2013 52 0.878 Y=-24.458+(1.094*X)

Hitchcock 2014 54 0.992 Y=2.537+(0.975*X)

Yale 2014 9 0.977 Y=1.195+(0.966*X)

Weighted Average 195 0.944

Summary Chart of the Correlation Coefficient

and Regression Analyses for Yield

Y = grain yield from yield monitor in bushels per acreX = grain yield from traditional calculations in bushels per acre

Results and Discussion

Location Year Entries

Top 25% Weigh Wagon

Top 25% Yield

Monitor % MatchWessington 2012 12 3 3 100%Woonsocket 2012 25 6 4 64%Hitchcock 2013 43 11 8 74%Wolsey 2013 52 13 12 92%Hitchcock 2014 54 14 13 96%Yale 2014 9 2 2 100%Average 195 49 42 86%

Top 25% of hybrids

Conclusions

Yield monitors can provide similar data compared to traditional weigh wagon methods.

• The larger sample size that is attainable with a yield monitor improves confidence in the results and wind is not a factor.• Moisture is tested throughout a strip rather than one sample, therefore a more representative measurement is evaluated.• GPS measures acres more accurately than a measuring wheel.• Data collection occurs immediately and accurately with the computer.• Corrections can occur if incorrect calibrations are determined.• Growers appreciate the simplicity and accuracy. There is a renewed interest in on farm testing.

Conclusions

The high correlation coefficient value suggests that yield monitors can be used effectively in on farm evaluation with the following suggestions:

• Ensure the yield monitor is properly calibrated.• Harvest a large plot area for increased accuracy.

Conclusions

In-Combine Hybrid Evaluation

Best Practices

Best Practices

Best Practices

Corrections?

Bushels production 24449.6 versus 30000.0

Acknowledgments

• Thank you to my cooperators, Sales Agronomists, Dr. Roger Elmore, Dr. Andrew Lenssen, and my managers.