(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 average management practices.

(2) Productivity is adjusted to reflect, as near as possible, average 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 is adjusted to reflect the 12-year countywide average spring wheat production as reported by Montana Agricultural Statistical Services;

(b) for irrigated lands, the soil survey productivity for tons of irrigated alfalfa hay per acre is adjusted on a county-by-county basis to reflect producer responses received during the 2008-2009 map mailing process and information obtained from irrigation districts. Since the soil survey productivity is based on a full application of water, the adjustment is made based on the amount of water the producer is actually able to apply on a regular basis; and

(c) for grazing land, the midpoint of production for the amount of air-dry herbage grown between "unfavorable" precipitation years and "normal" precipitation years is used to determine the land's productivity.