SR0085711_SSNL - Laserfiche WebLink

Home Browse Search

San Joaquin County, California The risk of flooding can be reduced by levees and diversions. 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 map unit is in capability units Illw-4 (MLRA-17), irrigated, and IVw-4 (MLRA-17), nonirrigated. It is in vegetative soil group B. 145—Dello loamy sand, drained, 0 to 2 percent slopes. This very deep, very poorly drained, nearly level soil is on flood plains. It formed in alluvium derived from granitic rock sources. Mottles in the profile indicate a very poorly drained soil; however, drainage has been improved by levees and reclamation projects. Elevation is sea level to 30 feet. The average annual precipitation is about 12 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 light yellowish brown loamy sand about 7 inches thick. The underlying material to a depth of 60 inches is pale brown and light gray, mottled sand. In some areas the surface layer is sandy loam or loamy fine sand. Included in this unit are small areas of Columbia soils and small areas of Dello soils that have a stratified medium textured to fine textured substratum below a depth of 40 inches. Both of these included soils are in landscape positions similar to those of the dominant Dello soil. Also included, on the slightly higher parts of the landscape, are Egbert and Merritt soils and small areas of coarse textured soils that have a weakly cemented substratum below a depth of 36 inches. Included areas make up about 15 percent of the total acreage. Permeability is rapid in the Dello soil. Available water capacity is low. The effective rooting depth is more than 60 inches. Drainage systems that require continual maintenance have been used to lower the apparent water table to a depth of 6 feet or more. Runoff is slow, and the hazard of water erosion is slight. The rate of water intake in irrigated areas is 3.0 inches per hour. The hazard of soil blowing is severe. The soil is subject to rare flooding, which occurs during years of abnormally high precipitation. Most areas are used for irrigated crops. 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 the low available water capacity and the high water table. General management considerations include the severe hazard of soil blowing. Because the soil is droughty, applications of irrigation water should be light and frequent. The water 53 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. A drainage system may be needed. 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 map unit is in capability units Illw-4 (MLRA-17), irrigated, and IVw-4 (MLRA-17), nonirrigated. It is in vegetative soil group B. 146—Dello loamy sand, partially drained, 0 to 2 percent slopes. This very deep, very poorly drained, nearly level soil is on flood plains and old slough remnants. It formed in alluvium derived from granitic rock sources. Mottles in the profile indicate a very poorly drained soil; however, drainage has been improved by levees and reclamation projects. Elevation is 10 feet below sea level to 10 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 dark grayish brown and brown loamy sand about 10 inches thick. The underlying material to a depth of 60 inches is light brownish gray, mottled fine sand and sand. In some areas the surface layer is fine sandy loam. Included in this unit are small areas of Devries, Egbert, Grangeville, Merritt, and Piper soils on the slightly higher parts of the landscape. Also included are small areas of Shima, Valdez, and Venice soils on the slightly lower parts. Included areas make up about 15 percent of the total acreage. Permeability is rapid in the Dello soil. Available water capacity is low. The effective rooting depth of the crops commonly grown in the county is limited by an apparent water table at a depth of 3 to 4 feet. Runoff is slow, and the hazard of water erosion is slight. The rate of water intake in irrigated areas is 3.0 inches per hour. The hazard of soil blowing is severe. The soil is subject to rare flooding, which occurs during years of abnormally high precipitation. Most areas are used for irrigated crops. 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 the low available water capacity and the high water table. General management considerations include the severe hazard of soil blowing. Areas adjacent to levees are subject to lateral seepage in wet years when the water level is high. Because the soil is droughty, applications of irrigation