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lim
<br />San Joaquin County, California
<br />6.
<br />This unit is suited to irrigated pasture. The main
<br />b. limitation is the low available water capacity. Because
<br />the soil is droughty, applications of irrigation water
<br />should be light and frequent. The water can be applied
<br />` by sprinkler and border methods. Leveling helps to
<br />ensure a uniform application of water. Proper stocking
<br />rates, pasture rotation, and restricted grazing during wet
<br />periods help to keep the pasture in good condition and
<br />protect the soil from compaction.
<br />If this unit is used for homesite development, the
<br />main limitation is depth to the hardpan. Ripping the
<br />L hardpan improves permeability and thus also improves
<br />the suitability of the soil for septic tank absorption fields.
<br />This map unit is in capability units Ills -8 (MLRA-17),
<br />` irrigated, and IVs -8 (MLRA-17), nonirrigated. It is in
<br />vegetative soil group G.
<br />230—Ryde clay loam, partially drained, 0 to 2
<br />percent slopes. This very deep, very poorly drained,
<br />nearly level soil is on flood plains and deltas. It formed
<br />in hydrophytic plant remains and in alluvium derived
<br />from mixed rock sources. Mottles in the profile indicate
<br />a very poorly drained soil; however, drainage has been
<br />improved by levees and reclamation projects. Elevation
<br />is 15 feet below sea level to 5 feet above. The average
<br />annual precipitation is about 14 inches, the average
<br />annual air temperature is about 60 degrees F, and the
<br />average frost -free period is about 270 days.
<br />Typically, the surface layer is grayish brown and dark
<br />gray, mottled clay loam about 24 inches thick. The
<br />underlying material to a depth of 63 inches is very dark
<br />gray and dark grayish brown, stratified mucky clay
<br />loam, silty clay loam, and muck. In some areas the
<br />surface layer is mucky clay loam or silty clay loam.
<br />Included in this unit are small areas of Egbert,
<br />" Guard, and Peltier soils in landscape positions similar to
<br />those of the Ryde soil and Scribner soils on the slightly
<br />higher parts of the landscape. Also included are small
<br />areas of Itano, Kingile, and Rindge soils in the slightly
<br />lower landscape positions. Included areas make up
<br />about 15 percent of the total acreage.
<br />` Permeability is moderately slow in the Ryde soil.
<br />Available water capacity is very high. The effective
<br />rooting depth of the crops commonly grown in the
<br />county is limited by an apparent water table that is
<br />regulated at a depth of 3 to 4 feet by pumping. This soil
<br />is subject to subsidence. Runoff is very slow, and the
<br />hazard of water erosion is slight. The rate of water
<br />intake in irrigated areas is 0.5 inch per hour. The
<br />hazard of soil blowing is moderate. The soil is subject
<br />to rare flooding, which occurs during years of
<br />abnormally high precipitation.
<br />Most areas are used for irrigated crops. This unit
<br />may provide wetland functions and values. These
<br />109
<br />should be considered in plans for enhancement of
<br />wildlife habitat or land use conversion.
<br />This unit is suited to irrigated row and field crops.
<br />The main limitations are subsidence and the high water
<br />table. General management considerations include the
<br />hazard of soil blowing. Because this soil is subject to
<br />differential subsidence, frequent leveling of the fields is
<br />needed to improve the efficiency of irrigation. Areas
<br />adjacent to levees are subject to lateral seepage in wet
<br />years when the water level is high. Careful applications
<br />of irrigation water are needed to prevent the buildup of
<br />a high water table. Large ditches and small spud
<br />ditches provide subirrigation and improve drainage.
<br />Subirrigation, furrow, border, and sprinkler systems are
<br />suitable. Where a subirrigation system is used, the
<br />water table is raised to a depth of 1 foot at planting time
<br />and then is slowly lowered during the growing season
<br />until it is at a depth of about 5 feet at harvest time.
<br />When the wind velocity is high in spring, the hazard of
<br />soil blowing can be reduced by properly managing all
<br />crop residue and by minimizing tillage. Levees should
<br />be checked periodically, and a proper maintenance
<br />program should be developed.
<br />This map unit is in capability units Illw-2 (MLRA-16),
<br />irrigated, and IVw-2 (MLRA-16), nonirrigated. It is in
<br />vegetative soil group E.
<br />231—Ryde silty clay loam, organic substratum,
<br />partially drained, 0 to 2 percent slopes. This very
<br />deep, very poorly drained, nearly level soil is on flood
<br />plains and deltas. It formed in hydrophytic plant remains
<br />and in alluvium derived from mixed rock sources.
<br />Mottles in the profile indicate a very poorly drained soil;
<br />however, drainage has been improved by levees and
<br />reclamation projects. Elevation is 15 feet below sea
<br />level to 5 feet above. The average annual precipitation
<br />is about 14 inches, the average annual air temperature
<br />is about 60 degrees F, and the average frost -free period
<br />is about 270 days.
<br />Typically, the surface layer is grayish brown and dark
<br />gray, mottled silty clay loam about 24 inches thick. The
<br />upper 16 inches of the underlying material is very dark
<br />gray and dark grayish brown, mottled silty clay loam.
<br />The lower part to a depth of 60 inches is black mucky
<br />peat. In some areas the surface layer is mucky clay
<br />loam or mucky silty clay loam.
<br />Included in this unit are small areas of Kingile,
<br />Rindge, Venice, and Webile soils in the slightly lower
<br />landscape positions. Also included are small areas of
<br />moderately fine textured soils that have an organic
<br />substratum at a depth of 30 to 40 inches. Included
<br />areas make up about 15 percent of the total acreage.
<br />Permeability is moderately slow in the upper part of
<br />the Ryde soil and rapid in the organic substratum.
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