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is available for irrigation in 8 out of 10 years for the crops commonly <br />grown) and of adequate quality; or, <br />(c) Aridic or tonic moisture regimes, and the area has a developed irrigation <br />water supply that is dependable and of adequate quality. <br />(ii) The soils have a temperature regime that is frigid, mesic, thermic, or <br />hyperthermic (pergelic and cryic regimes are excluded). These soils <br />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 <br />at this depth in soils with an O horizon is higher than 47o F (8o C); it is <br />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 <br />inches (1 meter) or in the root zone if the root zone is less than 40 <br />inches deep. <br />(iv) The soils either have no water table or have a water table that is <br />maintained at a sufficient depth during the cropping season to allow <br />cultivated crops common to the area to be grown. <br />(v) The soils can be managed so that, in all horizons within a depth of <br />40 inches (1 meter) or in the root zone if the root zone is less than 40 <br />inches deep, during part of each year the conductivity of the saturation <br />extract is less than 4 mmhos/cm and the exchangeable sodium <br />percentage (ESP) is less than 15.(vi) The soils are not flooded <br />frequently during the growing season (less than once in 2 years). <br />(vii) The product of K (erodibility factor) x percent slope is less than 2.0, and the <br />product of I (soils erodibility) x C (climatic factor) does not exceed 60. <br />(viii) The soils have a permeability rate of at least 0.06 inch (0.15 cm) per hour <br />in the upper 20 inches (50 cm), and the mean annual soil temperature <br />at a depth of 20 inches (50 cm) is less than 59o F (15o C). The <br />permeability rate is not a limiting factor if the mean annual soil <br />temperature is 59o F (15o C) or higher.(ix) Less than 10 percent of the <br />surface layer (upper 6 inches) in these soils consists of rock fragments <br />coarser than 3 inches (7.6 cm) in diameter. <br />(430-VI-NSSH, 1996) <br />(Revised June 2008) Attachment 2.04.9-4-3