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54 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. 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-16), irrigated, and IVw-4 (MLRA-16), nonirrigated. It is in vegetative soil group B. 147 ---Dello sandy loam, clayey substratum, 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 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 brown sandy loam about 16 inches thick. The underlying material is about 27 inches of white, mottled sand and loamy sand. Below this to a depth of 60 inches is a buried surface layer of gray, mottled silty clay and light brownish gray, mottled clay loam. In some areas the surface layer is fine sandy loam or coarse sand. Included in this unit are small areas of Columbia soils in landscape positions similar to those of the Dello soil and Merritt and Egbert soils on the slightly higher parts of the landscape. Also included are small areas of Dello soils that have a moderately fine textured overwash. Included areas make up about 15 percent of the total acreage. Permeability is rapid in the upper part of the Dello soil and slow in the clayey substratum. Available water capacity is moderate. The effective rooting depth is limited by a clayey substratum at a depth of 40 to 60 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 briefly perched above the clayey substratum 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. Most areas are used for irrigated crops. This unit may provide wetland functions and values. These Soil Survey 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 slowly permeable substratum and the high water table. General management considerations include the hazard of soil blowing. 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. 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-3 (MLRA-17), irrigated, and IVw-3 (MLRA-17), nonirrigated. It is in vegetative soil group B. 148—Dello clay loam, drained, 0 to 2 percent slopes, overwashed. 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 dark grayish brown clay loam about 12 inches thick. The underlying material to a depth of 60 inches is mottled sand and fine sand. In some areas the surface layer is loam, sandy clay loam, or silty clay loam. Included in this unit are small areas of Columbia soils in landscape positions similar to those of the Dello soil and Merritt and Egbert soils on the slightly higher parts of the landscape. Also included are small areas of Dello soils that have a stratified medium textured to fine textured substratum below a depth of 40 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 5 to 6 feet. Runoff is slow, and the hazard of water erosion is slight. The rate of water intake in irrigated areas is 0.5 inch per hour. The hazard of soil blowing is slight. 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.