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produce sustained high yields of crops in an economic manner when treated and managed, including <br />water, according to acceptable farming methods. In general, prime farmlands have an adequate and <br />dependable water supply from precipitation or irrigation, a favorable temperature and growing season, <br />acceptable levels of acidity or alkalinity, an acceptable content of salt and sodium, and few or no rocks. <br />They have soils that are permeable to water and air. Prime farmland is not excessively erodible or <br />saturated with water for a long period of time, and it either does not flood frequently or is protected from <br />flooding. Examples of soils that qualify as prime farmland are Palouse silt loam, O to 7 percent slopes; <br />Brookston silty clay loam, drained; and Tama silty clay loam, O to 5 percent slopes. <br />(2) Specific criteria. Terms used in this section are defined in USDA publications: "Soil Taxonomy, <br />Agriculture Handbook 436;" "Soil Survey Manual, Agriculture Handbook 18;" "Rainfall-Erosion Losses <br />from Cropland, Agriculture Handbook 282;" "Wind Erosion Forces in the United States and Their Use <br />in Predicting Soil Loss, Agriculture Handbook 346;" and "Saline and Alkali Soils, Agriculture Handbook <br />60." Prime farmlands meet all the following criteria: <br />(i) The soils have: <br />(a) Aquic, udic, ustic, or xeric moisture regimes and a sufficient available water capacity within a depth <br />of 40 inches (1 meter), or in the root zone (the root zone is the part of the soil that is penetrated or can <br />be penetrated by plant roots) if the root zone is less than 40 inches deep, to produce the commonly <br />grown cultivated crops (cultivated crops include, but are not limited to, grain, forage, fiber, oilseed, sugar <br />beet, sugarcane, vegetable, tobacco, orchard, vineyard, and bush fruit crops) adapted to the region in <br />7 or more years out of 10; or <br />(b) Xeric or ustic moisture regimes in which the available water capacity is limited, but the area has a <br />developed irrigation water supply that is dependable (a dependable water supply is one in which <br />enough water is available for irrigation in 8 out of 10 years for the crops commonly grown) and of <br />adequate quality; or, <br />(c) Aridic or torric moisture regimes, and the area has a developed irrigation water supply that is <br />dependable and of adequate quality. <br />(ii) The soils have a temperature regime that is frigid, mesic, thermic, or hyperthermic (pergelic and cryic <br />regimes are excluded). These soils have, at a depth of 20 inches (50 cm), a mean annual temperature <br />higher than 32o F (Oo C). In addition, the mean summer temperature at this depth in soils with an O <br />horizon is higher than 47o F (8o C); it is higher than 59o F (15o C) in soils that have no O horizon. <br />(iii) The soils have a pH between 4.5 and 8.4 in all horizons within a depth of 40 inches (1 meter) or in <br />the root zone if the root zone is less than 40 inches deep. <br />(iv) The soils either have no water table or have a water table that is maintained at a sufficient depth <br />during the cropping season to allow cultivated crops common to the area to be grown. <br />(Revised June 2008) Attachment 2.04.9-3-45