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. 4. 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 cam n to the area to be grown; and, <br />5. The soils can be managed so that, in all horizons within a depth of 40 inches (1 meter) or in the <br />root zone if the root zone is less than 40 inches deep), during part of each year the conductivity of <br />the saturation extract is less than 4 mmhos/cm and the exchangeable sodium percentage (ESP) is <br />less than 15; and, <br />6. The soils are not flooded frequently during the growing season (less often than once in 2 years) ; <br />and, <br />7. The product of K (erodibility factor) x percent slope is less than 2.0, and the product of I (soils <br />erodibility) x C (climatic factor) does not exceed 60; and, <br />8. The soils have a permeability rate of at least 0.06 inch (0.15 cm) per hour in the upper 20 inches <br />(50 cm) and the mean annual 0 soil temperature at a depth of 20 inches (50 cm) is less than 59 F <br />(150C) the permeability rate 18 not a limiting factor if the mean annual soil temperature is 59 0 F (15 <br />C)'or higher; and, <br />9. Less than 10 percent of the surface layer (upper 6 inches) in these soils consists of rock <br />fragments coarser than 3 inches (7.6 cm). <br />The following modifications and/or interpretations of the National Criteria for Prime <br />Farmlands were used in Colorado. <br />The soil must have: <br />1. A developed irrigation water supply that is dependable and adequate to meet moisture <br />requirements 8 out of 10 years and have 4 inches or more available water capacity within a depth of <br />40 inches (1 meter), or within the root Zone if the root zone is less than 40 inches; <br />(Revised 2/00) 2.04.9-66 <br />