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San Joaquin County, California 59 to lateral seepage in wet years when the water level is or regularly adding other organic material improves high. Careful applications of irrigation water are needed fertility, minimizes crusting, and increases the rate of to prevent the buildup of a high water table. Tile water intake. drainage can lower the water table if a suitable outlet is If this unit is used for homesite development, the available. Furrow, border, and sprinkler irrigation main limitations are the slow permeability, low strength, systems are suitable. When the wind velocity is high in and the high shrink-swell potential. On sites for septic . spring, the hazard of soil blowing can be reduced by tank absorption fields, the slow permeability can be properly managing all crop residue and by minimizing overcome by increasing the size of the absorption field, tillage. backfilling the trench with sandy material, and installing The Egbert soil is in capability units Ilw-2 (MLRA-17), long absorption lines. Properly designing buildings and irrigated, and IVw-2 (MLRA-17), nonirrigated. It is in roads can offset the limited ability of the soil to support vegetative soil group C. The Urban land is not assigned a load. Properly designing foundations and footings and a capability classification or a vegetative soil group. diverting runoff away from buildings help to prevent the structural damage caused by shrinking and swelling. 156—El Solyo clay loam, 0 to 2 percent slopes. Where this unit is used for dryland grain crops, the This very deep, well drained, nearly level soil is on low main limitation is low rainfall during the growing season. .. alluvial fans. It formed in alluvium derived from Because the amount of precipitation is not sufficient for sedimentary rock sources. Elevation is 60 to 300 feet. annual cropping, the best suited cropping system is one The average annual precipitation is about 10 inches, that includes small grain and summer fallow. the average annual air temperature is about 60 degrees Maintaining crop residue on or near the surface helps to F, and the average frost-free period is about 270 days. prevent excessive runoff and helps to maintain tilth and Typically, the surface layer is grayish brown clay the organic matter content. loam about 10 inches thick. The subsoil to a depth of This map unit is in capability units IIs-3 (MLRA-17), 60 inches is brown and pale brown silty clay loam. The irrigated, and IVs-3 (MLRA-17), nonirrigated. It is in soil is calcareous between depths of 10 and 60 inches. vegetative soil group A. In some areas the surface layer is silty clay loam. `. Included in this unit are small areas of Stomar, 157—Exeter sandy loam, 0 to 2 percent slopes. Vernalis, and Zacharias soils on the slightly higher parts This moderately well drained, nearly level soil is on low of the landscape. Also included, in landscape positions terraces. It is moderately deep to a hardpan. It formed ` similar to those of the EI Solyo soil, are small areas of in alluvium derived from mixed rock sources. A few soils that have a moderately fine textured surface layer areas are dissected by intermittent sloughs that have and have a gravelly or very gravelly moderately fine been filled as a result of land leveling. Elevation is 20 to textured substratum below a depth of 40 inches. 100 feet. The average annual precipitation is about 15 Included areas make up about 15 percent of the total inches, the average annual air temperature is about 60 acreage. degrees F, and the average frost-free period is about Permeability is slow in the EI Solyo soil. Available 270 days. � water capacity is very high. The shrink-swell potential is Typically, the surface layer and the upper part of the high. The effective rooting depth is 60 inches or more. subsoil are dark brown and brown sandy loam about 26 Runoff is slow, and the hazard of water erosion is inches thick. The next part of the subsoil is brown Slight. The rate of water intake in irrigated areas is 0.5 sandy clay loam and loam about 7 inches thick. The inch per hour. lower part to a depth of 60 inches is a brown, indurated Most areas of this unit are used for irrigated crops or hardpan. In some areas the surface layer is loam. orchards. A few areas are used for homesite Included in this unit are small areas of Kingdon and development or for dryland grain crops. Acampo soils in the slightly lower landscape positions This unit is suited to irrigated row, field, and orchard and Madera and San Joaquin soils on terraces. Also crops. The main limitation is the slow permeability. included are a few areas where depth to the hardpan is .Because of the restricted permeability, water as little as 15 inches, mainly where deep leveling cuts applications should be regulated so that the water does have been made. Included areas make up about 15 not stand on the surface and damage the crops. The percent of the total acreage. soil should be cultivated only within a narrow range of Permeability is moderate in the Exeter soil. Available moisture content. It is too sticky when wet and too hard water capacity is low. The effective rooting depth is when dry. Furrow, border, and sprinkler irrigation limited by the hardpan at a depth of 20 to 40 inches. systems are suitable. Returning crop residue to the soil Depth to the water table is more than 6 feet, but water