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San Joaquin County, California The main limitations are the low available water capacity and the high water table. Because the soil is droughty, applications of irrigation water should be light and frequent. The water should be applied in amounts sufficient to wet the root zone but small enough to minimize the leaching of plant nutrients. Careful applications of irrigation water are needed to prevent the buildup of a high water table. Tile drainage can lower the water table if a suitable outlet is available. Returning crop residue to the soil or regularly adding other organic material improves fertility, minimizes crusting, and increases the rate of water intake. This map unit is in capability units Illw-4 (MLRA-17), irrigated, and IVw-4 (MLRA-17), nonirrigated. It is in vegetative soil group B. 149—Devries sandy loam, drained, 0 to 2 percent slopes. This somewhat poorly drained, nearly level soil is on basin rims. It is moderately deep to a hardpan. It formed in alluvium derived from mixed rock sources. Mottles in the profile indicate a somewhat poorly drained soil; however, drainage has been improved by levees and reclamation projects. Elevation is 5 feet below sea level to 35 feet above- The average annual precipitation is about 14 inches, the average annual air temperature is about 60 degrees F, and the average frost -free period is about 270 days. Typically, the surface layer is grayish brown sandy loam about 13 inches thick. The upper part of the subsoil is light gray, mottled sandy loam about 15 inches thick. The lower part to a depth of 80 inches is a light gray, indurated hardpan. In some areas the surface layer is fine sandy loam or loam. Included in this unit are small areas of Dello, Guard, and Rioblancho soils in the slightly lower landscape positions; Tujunga soils in old, leveled sloughs; and Acampo soils on the slightly higher parts of the landscape. Also included are a few areas where depth to a hardpan is as little as 15 inches, mainly where deep leveling cuts have been made. Included areas make up about 15 percent of the total acreage. Permeability is moderately rapid in the Devries soil. Available water capacity is low. The effective rooting depth is limited by the hardpan at a depth of 20 to 40 inches. Drainage systems that require continual maintenance have been used to lower the apparent water table to a depth of 5 feet or more, but water may be perched above the hardpan after periods of heavy rainfall or irrigation. Runoff is slow. and the hazard of water erosion is slight. The rate of water intake in irrigated areas is 1.5 inches per hour. The hazard of soil blowing is moderate. The soil is subject to rare flooding, which occurs during years of abnormally high precipitation. 55 Most areas are used for irrigated crops. A few areas are used as irrigated pasture or for homesite development. This unit may provide wetland functions and values. These should be considered in plans for enhancement of wildlife habitat or land use conversion. This unit is suited to irrigated row and field crops. The main limitations are depth to the hardpan and the low available water capacity. General management considerations include the hazard of soil blowing. The hardpan limits the suitability for deep-rooted plants. Where feasible, deep ripping of this restrictive layer can help to overcome this limitation_ Because the soil is droughty, applications of irrigation water should be light and frequent. Careful applications are needed to prevent the buildup of a perched water table above the hardpan. A drainage system may be needed. Furrow, border, and sprinkler irrigation systems are suitable. A tillage pan forms easily if the soil is tilled when wet. Chiseling or subsoiling breaks up the pan. When the wind velocity is high in spring, the hazard of soil blowing can be reduced by properly managing all crop residue and by minimizing tillage. This unit is suited to irrigated pasture. The main limitation is the low available water capacity. Because the soil is droughty, applications of irrigation water should be light and frequent. The water can be applied by sprinkler and border methods. Leveling helps to ensure a uniform application of water. Proper stocking rates, pasture rotation, and restricted grazing during wet periods help to keep the pasture in good condition and protect the soil from compaction. If this unit is used for homesite development, the main limitation is depth to the hardpan. The rare flooding is a hazard. Ripping the hardpan improves permeability and thus also improves the suitability of the soil for septic tank absorption fields. Houses, roads, and streets should be constructed above expected flood levels. This map unit is in capability unit IVw-8 (MLRA-17), irrigated and nonirrigated. It is in vegetative soil group G. 150—Dumps. This map unit occurs as smoothed or uneven accumulations of refuse that cannot support plants unless major reclamation measures are applied. It is in scattered areas throughout the county. Included in this unit are Pits and Xerorthents. Included areas make up about 10 percent of the total acreage. Soil properties, such as permeability, drainage, runoff, effective rooting depth, and available water capacity, vary from one area to another. This unit is poorly suited to most land uses.