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Flashcards in Applied Information Technologies Deck (18):

Precision vs Accuracy

  • Prescision describes how close measured values are
    • 16, 10, 6 less precise than 11, 10, 9
  • accuracy 
    • how close measured value is to correct value
    • Correct value 10, 9 more accurate than 16



  • determine position of something with satellite positional info


Guidance system

  • Used to determin position of equipment on the surface of the earth to link that position with some activity
    • soil sampling, planting, fertilization, pesticide application, harvest


Remote sensing

  • use of sensors that detect radiation such as visible, infrared and radar reflecting from the surfaces which can be related to surface properties
    • such as crop type
    • crop yield
    • crop moisture status


Geographic info systems

  • consists of data that can be put in form of maps (
    • soil series
    • crop yield 
    • soil test values
    • versus position in the field
  • ) and used in site-specific management
  • relationships among maps can also be part of GIS


Crop Management Zone

  • an area of a field or fields that recieves the same crop input such as
    • fertilizer,
    • pest managment
    • irrigation
  • separate economically from other parts of the field or fields regarding that crop input 


Variable Rate Tech (VRT)

  • Applying inputs such as
    • seed
    • pesticides 
    • fertilizers 
  • at varying rates across a field
    • rate is varied in response to some field property changing spatially
      • irrigation
      • weed pop status
      • soil test values


Differentiate Management Zone, grid, field Composite

  • zone
    • area of land that has similar properties
    • can be managed in similar manner
    • may be within fields or across several fields
  • Grid Sampling
    • sampling soil , plants in a grid (2.5 acres) within or across fields
    • assesses variability in soil and plant properties
      • Defines management zones
  • Field Composite
    • soil / plant samples taken in areas that have similar properties
    • several subsamples are taken within each area, composited 
      • single sample analyzed


Soil Texture affect on yield variability

  • texture affect on yield variability
    • as clay content increases,
      • plant nutrient + supply 
      • pH buffering
      • avail water (to a point)
      • tendency to compact 
      • increases
  • As caly content increases
    • water infiltration
    • soil aeration
    • decreases


Soil Organic Matter on yield Variability

  • source of plant nutrients
  • improves soil condition
  • impacts soil biology including pests
    • (which may use soil organic matter in their life cycle)

more organic matter is more productive


How Factor Impacts Yield Variability

Soil moisture

  • Soil Moisture must be uniformly adequete for good yields


How Factor Impacts Yield Variability


  • impacts
    • infiltration
    • runoff / erosion
  • Yield decreases are
    • often found in low areas that collect excessive water 
    • steep areas where runoff rapid, infiltration low
  • decline in productivity when soils erode


How Factor Impacts Yield Variability

Pest distribution

  • can mirror soil properties if those soil properties affect growth and development of the pest
    • extremes in soil pH, soil organic matter, or soil water relations
  • if higher levels of pests are due to soil properties, yield declines are due to pest or pests


How Factor Impacts Yield Variability

Previous Management

  • can affect yield through
    • pest populations 
    • herbicide carryover
    • soil fertility
    • soil pH 
    • soil physical conditions


How Factor Impacts Yield Variability


  • can occur in localized areas of a field where conditions favor accumulation of soluble salts, sodium or carbonates
    • in excess these cause yield declines


How Factor Impacts Yield Variability

Nutrient Status and pH

  • can vary within field
    • if differences are sufficient, crop yields affected


How Factor Impacts Yield Variability

Soil Mapping Units

  • have yield potentials
  • if mapping units differen on a field, yield could be impacted


Lattitude and longitude

  • Lattitude (N,S) longitude (E,W)
  • can be expressed in degrees, minutes and seconds (fraction of 60)
    • south latitudes and west longitudes
      • can be expressed as negative numbers alone