What is Precision Farming

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Precision Farming in the South East
NESPAL UGA BIO AG ENGINEERING
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What is Precision Farming ?

• A management strategy which identifies, analyses
  and manages within field variability for
  increased profit and reduced environmental impact
• farming by the foot, farming by satellite, site
  specific management, prescription farming...

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Technologies behind PF

• Global Positioning System (GPS)
• Yield Monitoring
• Variable Rate Technology (VRT)
• Remote sensing
• Geographic Information system (GIS)

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GPS - What is it ?

• Navigation device which lets you pinpoint your
  location on the earths surface
• accurate to within a tennis court (SA off)

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GPS - How does it Work ?

• 24 orbiting satellites emitting radio signals
• Messages picked up
  by GPS receiver

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Differential Correction

• Correcting your normal GPS to give you accuracies
  down to below 1 meter (about 3 feet)
• Achieved by using a stationary base station GPS
  or subscription to commercial satellite broadcast
  service

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Satellite
Base Station
Receiver
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What is yield monitoring ?

• Sensors mounted on the combine measuring yield as
  the crop is harvested
• Coupled with a GPS logging location, data can be
  mapped

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Grain Crops

• Corn, Wheat, Canola, Soybean

GPS
Computer display
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Peanut
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PYMS Components
Omnistar DGPS antenna
5k load cells
palmtop computer
swath width indicator
junction box
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Cotton
Emitters
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Two Ways to a Profit Map
yield map October 1998
aerial photo 08 July 1998
profit map
classified image
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What does a yield map tell you ?

• Report card for field
• Quantifies variability within a field
• directs sampling to explain yield differences

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Corn 1995
Soybean 1995
Peanut 1997
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Variable Rate Technology

• Refers to any equipment designed to allow the
  rate of farm inputs to be precisely controlled
  and varied while the machine is in operation

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VRT - Sensor Based System

• Real time sensing and control
• Bowman Scan Ray

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VRT Fertilizer spreader
Application map
Computer display
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Variable rate system
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What is Remote Sensing

• Using satellite and aerial photography to see the
  big picture
• highlights variability within a field

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• Images may be made from color or infrared film

Color film image
Infrared image
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Ground Control Points

• Ground control points are the longitude and
  latitude of a specific target
• These target locations are later used to
  georeference an image

GPS antenna
Data logger
Ground control point
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What is georeferencing ?

• matching a specific longitude and latitude to a
  targeted location
• There are usually many targets within a field

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What is the advantage to georeferencing ?

• Georeferencing allows the image to be used as a
  map within the field
• a scout may go out to a field with a GPS and
  navagate to problem areas in the photo

Weed patches
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GPS Terms

• S/A Selective Availability
• Receiver
• Differential Correction
• Lat/Lon and UTM
• Landmarks/Waypoints
• Coast Guard Beacon
• WAAS (Wide-Area Augmented System)

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Specific uses for GPS

• Differential (1 m accuracy)
• Yield Monitoring
• Variable Rate Applications
• Field Scouting
• Non-Differential (Handheld)
• Dependent on accuracy
• Dependent on receiver, clear view of satellites,
  atmospheric disturbances)
• Field Scouting

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Handheld GPS

• Initialization
• Navigation Screens
• Storing Landmarks
• Routing
• GOTO
• Tracking
• Multi-Leg Route

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Initialization

• Lets Receiver know where it is
• Input time and date data
• Must be re-initialized if receiver has travelled
  more than xx miles from home, while off
• XX - 300 miles for Magellan 315
• XX- 500 miles for Garmin GPS III Plus
• Set-up

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Landmarks/Waypoints

• Position stored in memory
• Usually input by pressing Mark button
• Can be renamed, comments and messages
• Takes time because without keyboard, spelling
  words takes a while
• Can mark position of
• Home, campsites, tree stands, fishing holes
• Field positions known to have recurrent insect,
  disease or nutrient problems.

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Routing

• GOTO
• Usually have a GOTO button
• Select waypoint/landmark and receiver begins
  providing distance and bearing to landmark
• Tracking
• Turn tracking on (always on with Garmin GPS III)
• Store tracking into a route, can then backtrack
  to first spot, following trail used to get there
• Multi-Leg Routes
• Put waypoints in route and receiver will navigate
  to each point in order

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Routing

• Informational screens, navigation screens, pages
• Magellan has up to 9 screens and Garmin has up to
  6 pages
• Each page provides information on position and/or
  distance and direction to a waypoint/landmark

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Routing

• Status Screen (page)
• Shows number of satellites tracked and their
  position in the sky

N
1
EPE Estimated position Error DOP Degree of
Precision Require 3 satellites for 2-D position
and 4 satellites if 3-D (include
altitude) Ephemeris position and speed
of satellites
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45
Horizon
12
You
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Routing

• Compass screen (page)
• Shows number of satellites tracked and their
  position in the sky

N
Heading Direction of Travel Bearing Direction
should be going if navigating to a position
W
E
N
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Routing

• Position Screen (page)
• Lat/Lon or UTM position
• Time
• Speed
• Distance traveled
• Access to secondary coordinate

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GPS Scenarios for USE

• Finding field areas of interest
• History of disease, low soil fertility, insect
  pressure
• Mark area and give location a name.

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Routing

• Navigation screen(s)
• Basically same as compass screen
• BRG Bearing to spot you want to got to
• HDG Direction you are traveling
• SPD, XTE, DST
• Plot screen (map page)
• From Plot screen, it is easy to see landmarks
  already stored, tracks if tracking history is on,
  distance to landmarks
• Zoom in and out with arrow right and left key
  (page in and out)

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Blackshear
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Blackshear