Effectively Using GPS in Management

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Effectively Using GPS in Management

• Terry Griffin Jess Lowenberg-DeBoer
• Site Specific Management Center
• Purdue University

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Motivation

• Objective of on-farm trials is different from
  research trials
• Farmers want to make the best economic decisions
  for their operation
• Most farmers do not care about underlying
  mechanisms or whether results are generalizable
• For on-farm trials we need to shift focus away
  from research to farm management decision making

Photo Farmphotos.com
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Issues in Yield Data Analysis

• Why spatial analysis is important
• Quality yield monitor data
• Cleaning data
• On-farm comparisons
• Good experimental design
• Good research question
• Who offers quality spatial analysis?

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Spatial Analysis A Definition

• Spatial statistics assume that data is spatially
  correlated and explicitly includes that in the
  analysis. This is in contrast to the usual
  assumption of independent observations.
• Most yield monitor and other site-specific data
  is spatially correlated. If that correlation is
  not accounted for in the analysis, results will
  be biased and misleading.
• Yield monitor data with appropriate spatial
  analysis can lead to more reliable decision
  making with limited replications.

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Eyeballing vs Spatial Analysis

• The most common analysis for yield monitor data
  is eyeballing the maps to identify patterns.
• The human brain is good at finding visual
  patterns.
• It finds them whether they are there or not.
• Spatial analysis reduces the subjectivity in
  analysis of yield monitor and other precision
  agriculture data

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Spatial Effects in Point Patterns by location
not necessarily by value
Random
Clustered
Uniform/regular
Quiz!
Clustered!
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Data Quality

• Under certain conditions, harvester unable to
  make accurate measurements
• Remove erroneous data with protocol
• www.purdue.edu/ssmc
• Yield Editor software (USDA-ARS)

http//www.fse.missouri.edu/ars/YE/YE_Reg.ASP
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Flow Delay 8 seconds Start Pass Delay 8
seconds Max Velocity 6 mph Min Velocity
3.5 mph Smooth Velocity 20 Maximum Yield
330 bu Minimum Yield 50 bu STD Filter
plus/minus 3
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On-Farm Comparison Examples Using Spatial Analysis

• Soybean seeding rate in Montgomery County
• Nitrogen timing in Fayette County

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Example On-Farm Trial

• Central Indiana soybean seeding rate trial
• 80, 100, 120, 140, and 160K seeds per acre
• 4 replications in 1700 foot strips
• 30 inch rows
• Planter tractor has RTK-GPS auto-guidance
• End result is more reliable information
• A production recommendation
• Not a map

Photo Griffin Twilight Farms
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• Raw yield monitor data
• As-is from the combine
• No cleaning or filtering

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Yield data in GIS after removing erroneous
observations
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Yield data in GIS after removing erroneous
observations
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Yield monitor data used in analysis
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Rate trial 80K to 160K seeds per acre
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Major soil
Secondary soil
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2004 Soybean Seeding Rate Study
Major soil 100K profit max
Secondary soil 150K yield max
Secondary soil 120K profit max
Can reduce input costs by lowering seeding
population from 130K to about 100K on most of
the field, increasing planting timeliness
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On-farm Nitrogen Timing Study

• N-Timing study example
• Treatment A Preplant 100 of N at planting
• Treatment B Sidedress 100 of N at sidedress
• Treatment C Split 5050 planting and
  sidedress

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Raw yield monitor data
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Cleaned and filtered yield monitor data
With Yield Editor from USDA-ARS
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Proposed N timing experimental design

Preplant N
Corn following corn

Split N
Sidedress N
Corn following soybean
Split N
Preplant N
Split N
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N timing experimental design and field layout

Split N
Corn following corn

Sidedress N
Split N
Corn following soybean
Preplant N
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Soil A
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Soil B
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Corn Response to N Timing
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Economic Results of N Timing using custom
application rates
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On-Farm Research Results

• Split application highest yield AND profit
• On-farm tests provide reliable information

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On-Farm Experimentation Summary

• Spatial analysis converts farm-level data to farm
  management decision making
• Verify regional recommendations
• Fine-tune farm-level response
• More confidence in results and decisions

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Suggestions for On-Farm Trials

• Experimental designs include each treatment on
  each zone
• Electronically record as much as possible
• Must have planned comparison
• testable question
• data mining techniques not yet developed

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Extensions Role

• Support on-farm field-scale research
• Suggest appropriate experimental design
• Guide selection of treatments
• Facilitate spatial analysis
• Teach interpretation of analysis results
• Assist farm management decision making
• Make regional recommendations that often serve as
  a starting point for on-farm testing

Photo Griffin Twilight Farms
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Purdue Offers Spatial Analysis at the Top Farmer
Crop Workshop

• Participants bring on-farm trial data
• Spatial Analysis team analyzes data
• Farmers taught to interpret results
• The 39th Annual Top Farmer Crop Workshop planned
  for July 16-19, 2006
• Winter Yield Monitor Data Workshop
• November 14, 2005

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Summary

• Most farmers do on-farm comparisons.
• need reliable information for decision-making
• Spatial analysis converts data to information
• Extension can coordinate these relationships
• Winter Top Farmer Yield Monitor Workshop
• November 14, 2005
• Research supported by NCR USDA-SARE graduate
  student research grant

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• Jess Lowenberg-DeBoer
• 765.494.4230
• lowenbej_at_purdue.edu
• Terry Griffin
• twgriffi_at_purdue.edu
• 765.494.4257
• Site-Specific Management Center
• www.purdue.edu/ssmc
• Top Farmer Crop Workshop
• www.agecon.purdue.edu/topfarmer

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Software tools

• ESRI ArcGIS
• Yield Editor (USDA-ARS)
• GeoDa

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Free Software

• Yield Editor USDA-ARS (Drummond, 2005)
• http//www.fse.missouri.edu/ars/YE/YE_Reg.ASP
• GeoDa University of Illinois (Anselin, 2005)
• https//www.geoda.uiuc.edu/
• ArcGIS or ArcView GIS ESRI (Redlands, CA)
• http//www.esri.com

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Free ArcView 3.X Extensions

• XTools
• http//arcscripts.esri.com/details.asp?dbid11526
  
• Minnesota DNR
• http//www.dnr.state.mn.us/mis/gis/tools/arcview/
• Jenness Enterprises
• http//www.jennessent.com/arcview/arcview_extensio
  ns.htm
• SpaceStat ArcView Extension TerraSeer (Anselin)
• http//www.terraseer.com/products/spacestat.html