Precision Agriculture

1
Precision Agriculture

• Site-specific crop management
• Farming by the foot
• Farming by soil
• Variable rate agriculture
• Prescription farming
• Information agriculture

2
Concepts

• Vary management inputs according to actual needs
  in the field
• Field is not one uniform unit
• Should increase production efficiency economic
  returns
• Inputs applied only where needed
• Friendly to the environment

3
Yield-limiting Factors

• Nutrients
• Water
• pH
• Insects

• Weeds
• Disease
• Salinity
• Toxicity

4
Yield-limiting Factors

• Water is the most limiting factor to crop yields
• Nitrogen is the second
• Other nutrients or factors may limit yields if
  water and nitrogen are met
• Weather
• Water - related to soil depth
• Nutrient-holding capacity

5
Precision Agriculture Components

• Global Positioning Systems
• Geographic Information Systems
• Variable Rate Technology
• Infra-red Thermometry
• Multi-spectral Technology
• Electrical Conductivity Sensors
• Harvest Yield Monitors

6
Global Positioning Systems (GPS)

• Network of satellites (developed by DOD) that
  allows
• Position identification (within 1 to 10 m)
• lattitude
• longitude
• Elevation (about 10 x less precision)

7
GPS, continued

• Minimum of three satellites required to fix
  position
• Differential correction requires a base station
  at a known reference position to estimate
  introduced error
• Reduces error to a meter or less

8
Geographic Information Systems

• Software required to store and analyze the
  geo-referenced data
• Allows
• organization
• analysis
• interpretation (limited)
• visual presentation (stacked maps)

9
Variable Rate Technology

• Equipment with the ability to change the
  application rate and mixture as it moves across
  the field
• Uses on-board computer GIS with recommendation
  map of field
• Uses GPS to determine location in field

10
Variable Rate Technology

• For weed control, sprayers can be outfitted with
  sensors to see plants (weeds) growing in the
  interrow (furrow)
• When they see the weeds, they emit a signal to
  turn on the nozzle for a couple seconds
• Decreases herbicide requirement

11
Variable Rate Technology

• Adjust pesticide application rates to match soil
  types
• Adjust pesticide rates for specific problem areas

12
Variable Rate Technology

• Research continues into VRT planters that can
  adjust seeding rate according to soil potential
• Some are researching planters that can plant
  different hybrids as well

13
Infra-red Thermometry

• Used for years by DOD, now applied to agriculture
• The temperature of a crop canopy is indicative of
  stress
• Available from
• satellite
• low-platform fly-overs (aircraft)
• mounted to center pivot

14
Multi-spectral Technology

• Expanding the infra-red concept to include other
  wavelengths
• Yields more information, but little data is
  currently available for interpretation
• Colors may indicate yield potential or certain
  stresses insects, nutrients, etc.

15
Electrical Conductivity (EC) Sensors

• EC has long been used
• These sensors are disks pulled through the field,
  linked with an on-board computer, GPS, and GIS
• Generate EC map of field
• Provide much information, but interpretative
  ability is limited

16
Harvest Yield Monitors

• Available for combines
• Cotton yield monitors still need work
• Combine on-board computer, GPS, and GIS to create
  a yield map of field
• Requires some adjustment for speed lag

17
Soil Sampling

• Standard 1 sample for 10 to 40 ac
• Georeferenced soil sampling
• Grid or cell
• 0.25 to 2.5 acres per sample (10 to 30 per
  sample)
• Once every 5 to 7 years
• Variable rate fertilizer recommendation

18
Soil Sampling Directed

• Directed sampling Soil maps, yield maps or EC
  maps can be used
• May be more efficient and cost-effective
• Between intensive sampling years

19
Soil Sampling Grid Point

• Establish grids
• 2.5 acre cells, but varies
• Smaller grids increase precision and cost
• Collect 8 - 10 cores within 3 m (10 ft) diameter
  of each node
• Composite cores to get one sample
• Georeference sample using GPS

20
Scouting

• Scouting for weeds, insects, diseases, etc., can
  be geo-referenced
• All data can be incorporated into GIS map layers
  for that field
• Allows directed spraying, sampling, etc.

21
Soil Variability Short term

• Stable soil properties
• Texture
• Soil organic matter
• Dynamic soil properties
• Moisture
• Temperature
• pH
• Nutrients

22
Soil Variability Sources

• Natural
• Geological processes
• Pedological processes
• Anthropogenic
• Fertilizer Lime applications
• Manure application
• Cropping tillage systems
• Irrigation

23
Soil Variability Scales

• Micro-scale Less than 2.5 cm (1 in)
• Small-scale A few meters (yards)
• Horizons (layers in a soil)
• Soil Series (types)
• Field
• County
• Region, etc.

24
Challenges Technology

• Technology has advanced beyond knowledge
• Do not have enough information to interpret some
  data collected
• Many hypotheses, few facts or developed relations
• How much technology is enough?
• What sampling density is adequate?

25
Challenges Economics

• Annualize costs of soil samples
• Expensive equipment (yield monitors, etc.)
• Potentially decrease input costs, but may only
  redistribute them
• Can returns justify investments?
• May require using consultants (for both economics
  and technology