(1) Productivity is determined using the Natural Resource Conservation Service (NRCS) soil surveys. The productivity determination is specific to the agricultural land use classification under typical management practices.

(2) Productivity is adjusted to reflect, as near as possible, typical management practices for an area using the following procedures:

(a) for lands whose productivity is based on bushels of spring wheat per acre, the soil survey productivity in the following counties is adjusted on a regional basis by multiplying the soil survey productivity by the regional adjustment. The county designations and regional adjustments are as follows:

(i) Region 1: Beaverhead, Broadwater, Deer Lodge, Flathead, Gallatin, Granite, Jefferson, Lake, Lewis and Clark, Lincoln, Madison, Mineral, Missoula, Powell, Ravalli, Sanders, and Silver Bow is 0.86;

(ii) Region 2: Big Horn, Blaine, Carbon, Carter, Cascade, Chouteau, Custer, Fallon, Fergus, Garfield, Glacier, Golden Valley, Hill, Judith Basin, Liberty, Meagher, Musselshell, Park, Petroleum, Phillips, Pondera, Powder River, Prairie, Rosebud, Stillwater, Sweet Grass, Teton, Toole, Treasure, Wheatland, and Yellowstone is 0.77; and

(iii) Region 3: Dawson, Daniels, McCone, Richland, Roosevelt, Sheridan, Valley, and Wibaux is 0.70;

(b) for irrigated lands, the soil survey productivity for tons of irrigated alfalfa hay per acre is adjusted on a county-by-county basis;

(c) for grazing land, the production for the amount of air-dry herbage grown in "unfavorable" condition years is used to determine the land's productivity in animal unit months based on the requirements to sustain a 1,200-pound animal unit;

(d) the department will use the following formula to calculate the carrying capacity for nonirrigated native grazing land:

(i) per-acre per-year dry herbage production multiplied by 0.25 equals the per-acre per-year dry herbage production consumed by livestock;

(ii) per-acre per-year dry herbage production consumed by livestock divided by 1,098 pounds of dry herbage production consumed per-month per-animal unit equals the animal unit months per acre (AUMs/acre); and

(iii) livestock acres grazed multiplied by AUMs/acre equals the total AUMs; and

(e) for nonirrigated hay land, the midpoint production of the amount of air-dry herbage grown between "unfavorable" condition years and "normal' condition years divided by 2,000 pounds is used to determine the land's productivity in tons per acre.

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