Introduction to Precision Ag

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Introduction to Precision Ag

• Michael Spiess
• Department of Plant Science
• California State University, Fresno

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Its About Crop Yield VARIABILITY!

• Measuring
• Analyzing
• Managing

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Sources of Crop Yield Variability

• Soil
• Texture
• Salinity
• Fertility
• Compaction
• Organic Matter

• Disease
• Pests
• Water Management
• Weather
• Crop Genetics

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Its About Management

• Farming by the Square Foot

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Building Blocks ofPrecision Agriculture
A smorgasbord of technologies.
Direct Remote Sensing
Variable Rate Technology
Yield Monitors
Precision Navigation
Global Positioning Systems
Geographic Information Systems
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Precision Farming Cycle
Data Collection
Analysis
Farming
Management Decisions
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What is GIS?

• Maps Data

• Layers

• History

• Analysis by Location

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Why is GIS Important?

• Most data has a spatial component.
• GIS provides a method to
• Analyze the spatial component,
• Display the data spatially,
• And retrieve data spatially
• GIS is a MANAGEMENT TOOL
• Store traditionally collected data such as soil
  samples
• Foundation for Precision Ag.

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Farm GIS Layers

• Layers for
• Fields (Crop, Plant Date)
• Soil Map (Soil Type, Soil Class, S.I.)
• Fertility (N,P,K,.)
• Yield Maps
• Aerial Photos
• Remote Sensing Data
• As Applied Maps
• Pump Locations (yields, pwl, last test, pump)
• Irrigation Distribution (pipe type, size)
• Streets (Name, size) and Buildings

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Data Management Issues

• GIS data is valuable!
• GIS is an Information System and it requires
• Organization
• Regular Backup
• Management of Hardware and Software

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GPS
Global Positioning Systems
Geographic Information Systems
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What is GPS?

• Global Positioning System
• A satellite based positioning system
• Three Segments
• Space Segment - 24 satellites
• Control Segment (Military)
• User Segment (GPS Receiver)

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GPS Constellation
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User Segment

• Units receive transmission from Satellites
• Cost between 100 and 25000 (depends on
  accuracy)
• Must be line of sight with satellites

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How does it work?

• Position of satellites is known.
• The speed of the radio signal from each satellite
  is known
• Very accurate timing allows the calculation of
  the distance from each satellite.
• Using triangulation, the position of the receiver
  is calculated.

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GPS
http//wwwhost.cc.utexas.edu/ftp/pub/grg/gcraft/no
tes/gps/gps.html
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Differential GPS (DGPS)

• Used to correct for GPS errors
• Uses a ground station at a known location
• Ground station measures error of GPS signal by
  comparing the known location with the GPS
  location
• In real-time, the error transmitted to DGPS unit
  and position is corrected.

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Differential GPS (DGPS)
http//wwwhost.cc.utexas.edu/ftp/pub/grg/gcraft/no
tes/gps/gps.html
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Accuracy

• Usually given as the radius for percent of
  readings (50, 68, 95)
• GPS with Selective Availability off 13 m
• DGPS 1-3 m
• RTK GPS (2 cm)

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Example Accuracy
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Yield Monitoring
Yield Monitors
Global Positioning Systems
Geographic Information Systems
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Yield Monitoring

• Measuring yield on the fly
• Small Areas 100-1000 square feet
• Crops
• Grains
• Cotton
• Potatoes, sugar beets
• Peanuts
• Tomatoes

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Yield Maps
Field 18Yield 2.25 Bales/Acre
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Direct Remote Sensing
Direct Remote Sensing
Yield Monitors
Global Positioning Systems
Geographic Information Systems
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Remote Sensing

• Typically sensing from aircraft or satellite
• Sensing of visible and invisible electromagnetic
  spectra
• Commonly Blue, Green, Red, Near IR
• Typically 1m to 15m resolution
• Used to
• detect plant stress
• base mapping
• grape harvest
• map soil texture

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Sample 2m Data
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Direct Sensing

• Sensor is in direct contact
• Soil Conductivity
• Veris
• Electromagnetic sensors (Geonics EM-38)
• Soil moisture

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Soil Conductivity
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Grid Sampling

• Example Nitrate Nitrogen
• Max 115
• Min 9
• Mean 47
• SD 30

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Precision Guidance
Direct Remote Sensing
Yield Monitors
Precision Guidance
Global Positioning Systems
Geographic Information Systems
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Precision Guidance

• Tractor guidance at the centimeter level using
  GPS
• Benefits that may be achieved
• Increased speed of operation
• Operates at night and in fog
• Reduced cost of tractor ownership
• No guess row
• Reduce chemical cultivation costs
• Beds can be located over buried drip
• Increased field efficiency (0 overlap)

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Technologies

• RTK GPS (2 cm)
• Portable or Fixed based stations for correction.
• Manufacturers
• Beeline
• IntegriNautics (AutoFarm)
• Trimble

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Issues in Guidance and Operation

• Accuracy of the GPS
• Location of the antenna with respect to the
  ground
• Guidance between GPS readings (1/sec,
  5mph7ft/sec)
• Setup of tractor and implements
• System management to insure repeatability

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Variable Rate Technology
Direct Remote Sensing
Variable Rate Technology
Yield Monitors
Precision Navigation
Global Positioning Systems
Geographic Information Systems
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What is VRT/VRA?

• Also called Variable Rate Application (VRA)
• Site specific application of materials
• Used for
• Fertilizer and Soil Amendments
• Seeding
• Herbicide and Pesticides
• Material can be liquid or dry

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VRA Methods

• Application Maps (GIS)
• Requires GPS location
• Method of creating map (software)
• Ex. Use soil sampling data to create a variable
  rate application map.
• Sensor
• rate is varied by sensor on the applicator.

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Economic Issues

• PA technologies can be expensive to implement
• Return on investment will vary highly by
  individual situation
• Not all technologies are suited for a given crop
• Some benefits are easy to identify, others are
  not.