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~ co ('lj General Description of Soils and Soil Problems More than half the project acreage is comprised of soils that have developed in loess over sandstone shale and gravel outwash material. The remaining acreage is composed of soils which have developed from alluvium or undif- ferentiated loess and alluviumo Generally, the soils are deep, medium to fine textured, are high in silt and low in organic matter, have moderate to slow permeabilitq- and have a high water-holding capaci ty 0 Project soils generally have a moderate capa- city to hold nutrients and require additions of nitrogen and phosphorus to obtain good yields of adapted crops. Slopes range from less than 1 to 12 percent, with the majority between 4 and 12 percento Erosion is slight to moderate. Although local in nature, salinity, al~~li and high water table are problems in all geographic areas of the project where land is presently irrigated. These coexisting problems can be reduced, if not el iminated, by improving ~n-farm irrigation and improving drainage by providing adequate outlets and keeping outlets free of vegetation to allow a free flow of excess water. The Bureau of Reclamation plans to provide project drainage (digging new outlets and cleaning out natural drainageways) for areas in which there is a concentration of these problems. With the moderate to high sUt content of these soils and slopes from 1 to 12 percent, there is a general problem of soil erosion which can be kept to a minimum wi th applicable soil and water conservation practices. The fine textured soils require special management or a refinement of soil management practices to prevent puddling and compaction from tillage equip- ment, which take considerable time to correcto Factors affecting the capability classification of soils in this project are climate, fine surface texture, degree of salt, alkali, water table, stoniness, and percent slope. The acreage of land capability units within each evaluation area and soil and water relationships are shown in table 2. Project acreage and general soil characteristics for each land capability unit are shown in table 3. These units, tabulated by evaluation areas, allow a general appraisal to be made of each evaluation area and of differences between evaluation areas. Soils in capability class II have some limitations that reduce the choice of plants or require moderate conservation practices. Soils in capability class III have severe limitations that re- duce the choice of plants or require special conservation prac- tices or both. Soils in capability class IV have severe limita- tions that restrict the choice of plants or require very careful management or both. - 9 -