Part II: Section A
Using GIS Technology
2.2 Yield Factor Maps

Form used

To identify where grazing is occurring and flooding is a factor, and to detect any other potential impacts, the farmer should make frequent visits to the field. During these field visits, the farmer will use a handheld GPS unit and a camera to document ground-truthing data. This process was described in Part I, Section B of the manual. The information is recorded on the following form (Figure IIA-15).

Figure IIA-15: Ground-truthing data collection sheet.


Type of impact

A ground-truthing data form and its corresponding base map will be used for each field visit. The base map will indicate roughly where and which types of impacts are occurring in the field.

You should gather field data three times during the growing season:

  • Early grazing: Monitoring is conducted during late January/early February. This data includes all grazing and other impacts encountered at this time.
  • Mid-season grazing: Monitoring occurs around mid-March. Any grazing that takes place after the first monitoring will be included in this data set.
  • Late grazing: Extends from mid-March until geese depart the area (mid to late April) and includes all grazing that takes place after mid-March. Grazing at this time of the year usually is considered the most detrimental to crop production.

The data sheets for each period now must be converted into digital format. The steps needed to import a spreadsheet into ArcView GIS are explained in the following section, “Yield Mapping: Getting Yield Data into ArcView.”

With this data on yield factors, the provider should be able to create:

  • Spatial and temporal goose-grazing maps (Figures IIA-16 and IIA-17) that reflect classes of information similar to the following:
  Early grazing (through end of January/early February)
  Mid season grazing (through mid-March)
  Late grazing (through mid to late April)
  Continuous grazing (January through April)
  No grazing
  • Water damage
  • Weed invasion

Figure IIA-16: Examples of spatial maps showing timing of grazing.

Figure IIA-17: Example of spatial map showing timing and intensity of grazing.


<< previous page  
1. Introduction
2. Data Collection
- 2.1 Base Maps
- 2.2 Yield Factor Maps
- 2.3 Yield Map

3. Data Analysis
4. Findings/Summary
All information, data, design, and graphics are copyright (c) 2003 Dept of Rangeland Resources, Oregon State University. All rights reserved.