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San Joaquin County, California 115 7haterial improves fertility, minimizes crusting, and San Joaquin soils that have slopes of 2 to 5 percent maintains the rate of water intake. and are on the slightly higher parts of the landscape. This unit is suited to irrigated pasture. The main Also included are areas that have as much as 20 .mitation is the very low available water capacity. inches of overburden and areas where most of the soil General management considerations include the hazard horizons have been removed or altered as a result of f erosion. Because the soil is droughty, applications of land leveling. Included areas make up about 15 percent ligation water should be light and frequent. The water of the total acreage. can be applied by sprinkler and border methods. Permeability is very slow in the San Joaquin soil. seedbed preparation should be on the contour or Available water capacity is low. The shrink-swell ;ross the slope where practical. Proper stocking rates, potential is high. The effective rooting depth is limited 'pasture rotation, and restricted grazing during wet by the hardpan at a depth of 20 to 40 inches. Roots are periods help to keep the pasture in good condition and restricted to cracks and the faces of peds in the otect the soil from erosion. claypan, which is at a depth of 10 to 20 inches. Water _ Where this unit is used for dryland grain crops, the is briefly perched above the claypan and hardpan after main limitation is low rainfall during the growing season. periods of heavy rainfall or irrigation. Runoff is ponded 'eneral management considerations include the hazard in the small vernal pools, is very slow or ponded in the erosion. Because the amount of precipitation is not leveled areas, and is slow on the convex slopes. The sufficient for annual cropping, the best suited cropping hazard of water erosion is slight. The rate of water gvstem is one that includes small grain and summer intake in irrigated areas is 1.0 inch per hour. flow. All tillage should be on the contour or across the Most areas are used for livestock grazing or for aope. Leaving crop residue on or near the surface irrigated pasture, irrigated crops, or vineyards. A few helps to conserve moisture, maintain tilth, and control areas are used for dryland grain crops or for homesite osion. development. This unit may provide wetland functions This map unit is in capability unit IVe-3 (MLRA-17), and values. These should be considered in plans for irrigated and nonirrigated. It is in vegetative soil group enhancement of wildlife habitat or land use conversion. Where this unit is used for livestock grazing, general management considerations include saturated soil "238—San Joaquin loam, 0 to 2 percent slopes. conditions in concave areas following rainy periods. The This moderately well drained, nearly level soil is on low characteristic plant community is mainly soft chess, 'races. It is moderately deep to a hardpan. It formed ripgut brome, foxtail fescue, and filaree. Grazing should ..alluvium derived from granitic rock sources. The be delayed until the soil is firm enough to withstand native vegetation is mainly annual grasses, forbs, and trampling by livestock and the more desirable forage altered California white oak. The landscape is plants have had an opportunity to set seed. aracterized by a complex of gently sloping hummocks This unit is suited to irrigated pasture. The main and depressions, minor drainageways, and areas that limitations are the complex slopes and the low available "ve been leveled. Meandering drainageways and water capacity. Leveling helps to ensure a uniform sed depressions fill with water to form vernal pools application of water. Because the soil is droughty, the Gering the winter in many areas. Elevation is 20 to 100 applications should be light and frequent. The water can feet. The average annual precipitation is about 16 be applied by sprinkler and border methods. Proper i ihes, the average annual air temperature is about 61 stocking rates, pasture rotation, and restricted grazing 6–grees F, and the average frost-free period is about during wet periods help to keep the pasture in good 275 days. condition and protect the soil from compaction. Typically, the surface layer and the upper part of the This unit is suited to irrigated row, field, and vineyard )soil are brown loam about 16 inches thick. The next crops. The main limitations are the complex slopes, Fart of the subsoil is a claypan of brown clay about 10 depth to the very slowly permeable claypan and inches thick. The lower part to a depth of 60 inches is a hardpan, and the low available water capacity. Leveling I rwn, light brown, and strong brown, indurated helps to ensure a uniform application of water. Because hardpan. In some areas the surface layer is fine sandy of the restricted permeability, the applications should be loam. regulated so that the water does not stand on the Included in this unit are small areas of Hollenbeck surface and damage the crops. The hardpan limits the r_J Galt soils in the slightly lower landscape positions, suitability for deep-rooted crops. Where feasible, deep moderately coarse textured soils that have a hardpan at ripping of this restrictive layer can help to overcome this r 4epth of 12 to 20 inches and are in landscape limitation. A tillage pan forms easily if the soil is tilled I_itions similar to those of the San Joaquin soil, and when wet. Chiseling or subsoiling breaks up the pan.