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