How to Use the AUM Estimator

Note: Output will be in Animal Unit Months (AUMs) for the entire parcel being estimated.

Question: Is a soil survey available for the parcel to be calculated?

If YES, download the AUM Estimator Worksheet, then follow the steps to using the AUM estimator listed below.

If NO, and the estimate is to be used for Montana Department of Revenue purposes, contact your county agricultural extension agent for an AUM estimate. If NO, and the estimate is to be used for conservation planning, the local Natural Resources Conservation Service office will provide the estimate using ecological site descriptions.

Download the AUM Estimator Worksheet

Note: The following documents should be saved to your computer and opened with Microsoft Word or Adobe Reader before filling in the worksheet.

If you encounter any problems with the file provided on this page, please contact Technical Resources at 406-587-6822.

View or download the AUM Estimator Worksheet in either of the following formats. The following documents require either Microsoft Word or Adobe Reader.

AUM Estimator Worksheet (DOC; 61 KB) Calculations must be done manually.
AUM Estimator Worksheet (PDF; 94 KB) Calculations are done automatically.

Steps to Using the AUM Estimator

Step 1. Using existing soil survey information, determine the soil map units that occur in the parcel. For sources of soil survey information, see Soil Maps.

Step 2. Estimate the acres of each soil map unit; then enter the Map Unit Symbol into column A and the Acres of this Map Unit in the Parcel into column B of the AUM Estimator Worksheet available above. The value in column B could be based on GIS calculations (ArcView calculations), dot counting with an acreage grid, or simply visually estimating the proportion of the different map units that occur in the parcel being estimated.

Step 3. Using the figures under the Range AUM (shortened for AUM/Acre) Column (use the below normal column for Montana Department of Revenue calculations or the appropriate column based on the predominant plant community for other uses) based on the Soil Survey Area Estimated AUM (shortened for AUM/Acre) Table for the survey area(s), populate Column C of the AUM Estimator Worksheet. Calculate Column D (Map Unit AUMs in this Parcel) using the directions as noted (see the Example Worksheet after Step 4. below). The Soil Survey Area Estimated AUM Table can be accessed via the web at: http://www.mt.nrcs.usda.gov/technical/ecs/range/aum.

Directions for Columns in the AUM Estimator Worksheet:

A. List map unit symbol(s) for parcel from soil survey map.
B. Enter acres of listed map unit in parcel (from published soil survey map or ArcView calculation).
C. Enter the AUM/Acre from the appropriate Column in the Soil Survey Area Estimated AUM Table for the soil survey area(s). These values will be either range AUM/Acre as listed in the Estimated AUM/Acre Table or dry pasture AUM/Acre as a 1.5 factor of the range AUM/Acre, depending upon current land use.
D. Multiply Columns B and C, and enter the results in Column D.

Step 4. Add the values in column D to obtain the Total Estimated Parcel AUMs. Use the Total Estimated Parcel AUMs in your specific application. In the case of the example below, the number would be 13.22 AUMs for the entire 32.7 acre parcel.

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