Table Talk: Information That Powers Open Fields

Open Fields is Cloudpoint's offering for assessing farmland value using ArcGIS Pro. In addition to using GIS data layers such as parcels, land use classification, and soils, the tool uses data tables provided on an annual basis by the Illinois Department of Revenue (Publication 122-Instructions for Farmland Assessments). The tables, and how they relate to farmland assessment in Open Fields, are described below.

Table 1: Certified Values for Assessment Year

The Certified Values table changes annually and lists the Agricultural Economic Value, the Equalized Assessed Value, and the Certified Value per acre for the assessment year as it corresponds to the Average Management Productivity Index. Each year, the values are certified by the Farmland Assessment Technical Advisory Board. Open Fields uses the Certified Value (CV) and Productivity Index (PI) attributes in calculations and output for a Farmland Assessment Report.

Table 2: Productivity of Illinois Soils Under Average Management

The Productivity of Illinois Soils table is an extensive list (20 pages!) of Illinois soil types and their codes, the subsoil rooting designation, and the associated Productivity Index (PI). The entirety of this table is built into the Open Fields tool and is also a factor in the Farmland Assessment Report output.

Table 3: Slope & Erosion Adjustment Table

The Slope and Erosion Adjustment Table is another important factor for determining farmland assessment with Open Fields, and is a table that is built directly into the tool.

This table provides values to use to adjust the Productivity Index (PI) based on a Midslope value (from the Soils GIS data), as well as if the soil is subject to slight, moderate, or severe erosion. The Subsoil Rooting category from Table 2 determines whether to use the Favorable or Unfavorable sections of this table.

There are other tables within Publication 122 that accompany Table 3 and are used to determine the adjustment for slope and erosion.

The table above lists Letter Codes that are associated with certain Soil Codes in the Soils GIS data when the Midslope value equals the value in the far right column. That Percent Slope value is used to reference which line to use in Table 3 for the slope adjustment.

The table below shows a number value that is associated with a Letter Code above in the Soil Code in the Soils GIS data, and a description of the degree of erosion.

For example, Birkbeck silt loam-233B2.

Using Table 2, it is determined that this soil type has a Favorable designation for Subsoil, and that the PI is 108.

Using the Slope and Erosion charts, "B" means that the Percent Slope to use is 3, and the degree of erosion, 2, is moderate.

With that information, Table 3 shows that the slope and erosion adjustment factor for a Percent Slope of 3 in the Favorable category is .95. The Adjusted PI calculates to 103.

Rather than a person reading through tables and doing the math, Open Fields makes these calculations in seconds, and outputs the information in a nicely formatted report!

If you would like to learn more about Open Fields and how it can assist with your farmland assessments, contact us today!