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<br />I;'J <br />C') <br />0': <br /> <br />C, Soils are generally low in fertility and organic matter. The application <br />of ni trogen and phosphorus fertilizers, plus an improved water supply will <br />increase crop yields. and, over along period of time, maintain the organic <br />matter at a slightly higher level. <br /> <br />At present, soils which have developed from Mancos shale do not contain <br />significant amounts of soluab1e salts. However, these soils could become <br />highly saline if salts dissolved from the underlying shale are moved upward <br />through the so il. <br /> <br />Interpretive Groupings of Soil Characteristics <br /> <br />The U.S. Department of Agriculture maps the basic soil characteristics. <br />These characteristics are used for many types of interpretive groupings. <br />One t;ype is the land capability Classification, expressing the int.ensity <br />of treatment which the land needs to prevent soil deterioration and assure <br />its continued producti vi ty. The lands considered in the survey are shown <br />in this report by land capability units. This intemediate step in the <br />evaluation of a project, enables a quick appraisal of soils and the management <br />required to cultivate them over a long period without deterioration. <br /> <br />The Department of Agriculture also interprets the basic soil facts mapped <br />in the field to make another grouping of project lands into evaluation areas. <br />The soils, climate, water supply and other plvsical factors in each evaluation <br />area reflect similar crop adaptations, productivity, land development require- <br />ments and production costs. <br /> <br />The land capability classification shows the national system and the acreage <br />of project land in each land capability unit. (Table 2) <br /> <br />Land Capability Classification <br /> <br />For classification purposes, soU mapping uni ts are grouped into land <br />capability units which include the class, subclass and unit. <br /> <br />Example: <br /> <br />Land capability unit <br /> <br />II <br /> <br />s <br /> <br />2 <br /> <br />II - Represents the land capability class, which is one of eight broad <br />national classes of land. <br /> <br />s - Represents the subclass, which is one of four broad national <br />divisions of the land capability class. <br /> <br />2 - Represents the unit, which is a local division of the subclass <br />identifying a specific land condition. <br /> <br />- 9 - <br />