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130 Soil Survey ' gray, and pale brown clay. The next 10 inches is pale selected for planting. Irrigation water can be applied by brown silty clay loam and light grayish brown, mottled sprinkler and border methods. Leveling helps to ensure clay loam. The lower part to a depth of 60 inches is a a uniform application of water. Proper stocking rates, light brownish gray, indurated to strongly cemented pasture rotation, and restricted grazing during wet ' hardpan. The soil is saline-sodic throughout. In some periods help to keep the pasture in good condition and areas the surface layer is loam or silty clay loam. protect the soil from compaction. Included in this unit are small areas of Manteca, This map unit is in capability units Illw-6 (MLRA-17), ' Veritas, and Tinnin soils on the slightly higher parts of irrigated, and IVw-6 (MLRA-17), nonirrigated. It is in the landscape. Included areas make up about 15 vegetative soil group F. percent of the total acreage. Permeability is very slow in the Trahem soil. 259—Tujunga loamy sand, 0 to 2 percent slopes. ' Available water capacity is moderate. The shrink-swell This very deep, somewhat excessively drained, nearly potential is high. The effective rooting depth of the level soil is on flood plains and elongated channel crops commonly grown in the county is limited by the remnants. It formed in alluvium derived from granitic ' hardpan at a depth of 20 to 40 inches and by an rock sources. Elevation is 40 to 70 feet. The average apparent water table that has been lowered to a depth annual precipitation is about 11 inches, the average of 4 to 6 feet through drainage systems that require annual air temperature is about 60 degrees F, and the continual maintenance. Runoff is slow, and the hazard average frost-free period is about 270 days. of water erosion is slight. The rate of water intake in Typically, the surface layer is brown loamy sand irrigated areas is 0.5 inch per hour. The soil is subject about 22 inches thick. The underlying material to a to rare flooding, which occurs during years of depth of 67 inches is pale brown loamy sand. In some ' abnormally high precipitation. areas the surface layer is loamy coarse sand. Most areas are used for irrigated crops or pasture. . Included in this unit are small areas of Honcut. This unit may provide wetland functions and values. Tokay, and Veritas soils on the slightly higher parts of These should be considered in plans for enhancement the landscape. Also included, in landscape positions of wildlife habitat or land use conversion. similar to the Tujunga soil, are small areas of Columbia This unit is suited to irrigated row and field crops. soils and soils that are gravelly and coarse textured. The main limitations are the saline-sodic conditions, the Included areas make up about 15 percent of the total ' very slow permeability, depth to the hardpan, and the acreage. high water table. The content of salts can be reduced Permeability is rapid in the Tujunga soil. Available by leaching, applying the proper amount of soil water capacity is low. The effective rooting depth is 60 amendments, and returning crop residue to the soil. inches or more. Runoff is slow, and the hazard of water ' Because of the restricted permeability, water erosion is slight.The rate of water intake in irrigated applications should be regulated so that the water does areas is 3.0 inches per hour. The hazard of soil blowing not stand on the surface and damage the crops. Careful is severe. The soil is subject to rare flooding, which ' applications are needed to prevent the buildup of a high occurs during years of abnormally high precipitation. water table. Tile drainage can lower the water table if a Most areas are used for irrigated crops or orchards. suitable outlet is available. Intensive management is This unit may provide wetland functions and values. required to reduce the salinity and maintain productivity. These should be considered in plans for enhancement ' The hardpan limits the suitability for deep-rooted crops. of wildlife habitat or land use conversion. Where feasible, deep ripping of this restrictive layer can This unit is suited to irrigated row, field, and orchard help to overcome this limitation. Furrow, border, and crops. The main limitation is the low available water ' sprinkler irrigation systems are suitable. Returning crop capacity. General management considerations include residue to the soil or regularly adding other organic the severe hazard of soil blowing. Because the soil is material improves fertility, minimizes crusting, and droughty, applications of irrigation water should be light increases the rate of water intake. and frequent. The high percentage of sand in the soil ' This unit is suited to irrigated pasture. The main reduces the amount of moisture available for plant limitations are the saline-sodic conditions. The growth. Sprinkler and drip irrigation systems are concentration of salts and sodicity in the surface layer suitable. They permit an even, controlled application of ' limit the production of plants suitable for irrigated water, help to prevent excessive runoff, and minimize pasture. Leaching the salts from the surface layer is the risk of erosion. A tillage pan forms easily if the soil difficult because of the high water table. A drainage is tilled when wet. Chiseling or subsoiling breaks up the ' system and irrigation water management reduce the pan. When the wind velocity is high in spring, the concentration of salts. Salt-tolerant species should be hazard of soil blowing can be reduced by properly