Yield Mapping Systems

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Yield Mapping Systems
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Yield Mapping Functions

• Measure mass harvested within a known area
• Record mass and crop attributes (moisture, et
  al.) by position
• Record operator observations of field conditions

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Potato Yield Variability
Courtesy Harvestmaster Inc.
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Status of Yield Mapping

• Commercial
• Grain
• Potatoes
• Cotton
• Belt harvested vegetables
• Tomatoes
• Grapes

• Research Dev.
• Peanuts
• Forage
• Tree fruit

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Yield Mapping System Components
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Yield Mapping Components

• Positioning system
• Operator console/data logger
• Forward travel sensor
• Mass flow sensors
• Harvest indicator

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Yield Mapping Components

• Positioning system differentially corrected GPS
  receiver
• The GPS receiver is the primary difference
  between yield mapping and monitoring.

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Deere Starfire GPS Receiver
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Yield Mapping Components

• Positioning system
• Operator console/data logger

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Ag Leader Console/Data logger
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Yield Mapping Components

• Positioning system
• Operator console/data logger
• Forward Travel Sensor

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Forward Travel Sensing

• Wheel rotation
• inexpensive
• high error in wet conditions

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Forward Travel Sensing

• Wheel rotation
• Radar
• accurate under many conditions
• moderate cost

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Forward Travel Sensing

• Wheel rotation
• Radar
• GPS indicated travel distance
• no additional cost
• inaccurate for slow moving harvesters (GPS
  velocity resolution 0.05 m/s)

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Yield Mapping Components

• Positioning system
• Operator console/data logger
• Forward Travel Sensor
• Mass Flow Sensors
• crop
• moisture

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Mass Flow Sensor Types

• Grain
• impact, weighing, optical, radio frequency
• Cotton
• optical, weighing (research)
• Vegetables, Root crops
• weighing

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Measures mass by motion of impact plate with
grain striking.
John Deere Grain Impact Sensor
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Ag Leader Impact Sensor
Measures mass from strain caused by impact of
grain
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Ag Leader Cotton Flow Sensor
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Ag Leader Moisture Sensor
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Harvestmaster Weighing Sensors
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Idler Wheel Load Cells
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Installed Idler Wheel
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Yield Mapping Components

• Positioning system
• Operator console/data logger
• Forward Travel Sensor
• Mass Flow Sensors
• Harvesting Indicator

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Harvesting Indicator

• Indicates when machine is actually harvesting and
  not just traveling in field
• Often based on position of gathering parts of
  harvester
• Controls recording of data

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Header down in recording position
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Yield Calculations

• Measure mass harvested over a period of time
• Measure the distance traveled during that same
  period
• Determine area from distance and effective
  harvest width (set by operator
• Yield mass/area

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W
Z
D
Yield Mass / W D
W-indicated width, Z-actual harvest width
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Harvester Dynamics

• Time between actual harvest and mass flow
  measurement must be corrected for accurate maps
• Delay values depend on harvester

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Grain Flow Delay
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Procedures for Accurate Yield Mapping
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Yield Mapping Operations

• Enter information needed before harvest
• field names
• yield unit test weights
• varieties
• flags

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Yield Mapping Operations

• Set up customers, field names, flags in advance
• Calibrate the system

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Calibration Procedures

• Select appropriate harvest width
• Calibrate speed sensor (ground or radar)
• Weigh loads of at least 1500 kg.
• Case/Ag Leader Grain- multiple flows
• Deere Grain/Ag Leader Cotton - single flow rate

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Yield Mapping Operations

• Set up customers, field names, flags in advance
• Calibrate the system
• Alternate passes of mapping and non-mapping
  combines

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Yield Mapping Operations

• Set up customers, field names, flags in advance
• Calibrate the system
• Alternate passes of mapping and non-mapping
  combines
• Dont record data over harvested areas

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Yield Mapping Operations

• Avoid partial cutting width situations.

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Differences between indicated and actual harvest
width result in erroneous yield estimates.
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Yield Mapping Operations

• Avoid partial cutting width situations.
• Raise header to disable data recording when
  traveling in field.

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Yield Map Creation
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Yield Map Creation and Use

• Data transfer
• Mapping Software
• Filtering Data
• Legend Selection
• Map Interpretation

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Data Transfer

• PCMCIA memory cards manually carried to computer
  today
• Future simultaneous wire-less transmission?

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Yield Mapping Software

• Vendor-supplied mapping software -
  visualization, filtering, export, archive
• GIS - import data, filtering, analysis

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Mapping Software

• Downloads files from PC card
• Creates field summaries of area harvested and
  total mass
• Displays yield data as points or surface
• Filtering based on min/max limits
• Exports data in ASCII format

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Export Formats

• Format differs for each manufacturer and crop
  type
• Two general forms
• basic - position, yield, flags
• advanced - all recorded information

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Ag Leader Grain Basic Format
Latitude -97.1464 Longitude
31.03174 Yield (bu/ac) 123.4 Moisture 13.6 Ser
ial No. 971125 Field Id F123A Load
Id L12 Grain Corn
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JDmap Grain Export Format
Longitude Latitude Flow (lbs/sec) Time (GPS
sec) Cycles Distance (in) Swath (in) Moisture
() Status Pass
Serial No. Field Id Load Id Grain
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JDmap Export File Example
-96.197128,29.593638,1.90,25968064,
1,57,288,0.00,1,1,4596, "F1 Buckmaster A","L1
", "Rice (Long)","Jefferson"
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GIS Software

• Provides visualization capability like the
  manufacturers software
• Provides additional filtering and analysis
  capability

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Filtering to Remove Inaccurate Yield Data
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Data filtering and correction

• Reject values beyond upper and lower threshold
  limits
• Realignment of non-parallel GPS values
• Shift in time to correct lag
• Delete overlaps and partial width data

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Operator error
GPS error
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Map with bad data due to operator errors
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After filtering
Before filtering
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Yield layer creation

• Automatic creation in manufacturers software
• Manual entry of exported yield files in GIS
  packages
• Automated entry of exported yield files in some
  GIS programs

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Legend Selection

• Number of classes
• Selection of class limits
• Colors

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Legend Selection

• Number of classes
• Visual filtering process to reduce the amount of
  information
• Humans have difficulty recognizing more than 10
  different classes
• 4-6 is optimum

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Legend Selection

• Selection of class limits
• Software has default methods, but these are
  generally not optimum
• Select limits that have meaning for management

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Legend Selection

• Colors
• Rainbow selection best for viewing differences
• Two color shading shows transitions

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Point vs. Contour

• Point maps show details and allow for human
  interpretation
• Contour maps show primary trends

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Point Map
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Grid map with yields averaged in each cell
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Yield Map Interpretation
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Yield maps are ...
intensive field description
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Exported yield files is 11 Mbytes.
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Yield maps are ...

• intensive field description
• information rich but difficult to interpret
• useless without supporting knowledge of the field

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Yield maps are ...

• generating many questions
• confounded with actual yield variability and both
  system and operator errors

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Yield map interpretation

• Must start at the beginning of the growing season
• tillage
• seedling emergence
• weed problems
• insect problems

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Yield map interpretation

• Must start at the beginning of the growing season
• Incorporate available information
• soil survey
• aerial photos
• past management

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Yield map interpretation

• Must start at the beginning of the growing season
• Incorporate available information
• Conduct diagnostic surveys
• soil sampling