Precision Farming: A Comprehensive Approach

Authors: Robert "Bobby" Grisso, Extension Engineer, Biological Systems Engineering; Mark Alley, Extension Agronomist & Professor, Crop & Soil Environmental Sciences; Phil McClellan, President, MapTech, Inc., Blacksburg, VA; Dan Brann, Extension Grain Specialist, Crop & Soil Environmental Sciences; and Steve Donohue, Extension Agronomist & Professor, Crop & Soil Environmental Sciences; Virginia Tech

Publication Number: 442-500, posted August 2002

Table 2. Guide to interpreting (or detecting) variability within a yield map (or field). Visual observations from a yield map can be seen as having uniform or irregular patterns (from Lotz, 1997).

Pattern Description/Explanation

Uniform Patterns
With Direction of Application

• change in planting date
• change in hybrid/variety
• change in chemical application
• selected rescue treatment
• chemical skips and misapplications
• equipment errors
• poor straw/chaff distribution
• compaction

Against Direction of Application

• drain tile patterns
• historically different fields
• old traffic patterns
• manure applications
• pipelines/phone lines underground
• previous compaction

Irregular Patterns
Irregular Line

• topography changes
• herbicide drift
• border shading effects
• insect infestation from bordering lands
• improper manure application
• waterways

Irregular Area/Patch

• change in soil type
• drainage patterns
• weed infestations
• soil fertility changes
• previous crop activity
• disease infestations
• herbicide carryover
• historic occurrences
• insect infestations
• changes in organic matter
• animal damage
• wet areas

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