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<br /> <br />~~~~~~~~ <br />SEP 13 i985 <br />RECL MIATION D VISION <br />20--Derrick very gravelly loam, 0 to 3 percent slopes. This deep, <br />well drained soil is on alluvial valley floors, fans and terraces. Elevation <br />is 7,600 to 7,900 feet. It is formed in meduim textured gravelly alluvium. The <br />average annual precipitation is about 7 inches, average annual air temperature <br />is about 41 degrees F, and frost-free period is about 95 days. <br />Included in mapping are small areas of Graypoint gravelly sandy loam, and <br />San i~rcacio sandy loam. <br />Typically, the surface layer is pale brown very gravelly loam about 4 inches <br />thick. The subsoil is yellowish brown very gravelly .sandy clay loam in the upper <br />5 inches and is yellowish brown very gravelly heavy sandy loam with visible calcium <br />carbonate in the lower 4 inches. The substratum is extremely gravelly sand with <br />about 20 percent cobble and extends to 60 inches. <br />Permeability is moderate. Effective rooting depth is 60 inches or more. <br />Available water capacity is low. Surface runoff is slow and the hazard of erosion <br />is slight. <br />This soil is used for range and wildlife with a few areas used for irrigated <br />pasture and hayland. Application of commercial fertilizer is needed in addition to <br />,manure and plant residues, on the irrigated areas. <br />Irrigation methods suitable for this soil are borders with short lengths of <br />run, and sprinklers. <br />The potential vegetation on this soil is dominated by blue grams, Indian rice- <br />grass, western wheatgrass,'i~eedle-and-thread, winterfat, and fourwing saltbush. When <br />the range deteriorates, the proportion of Indian ricegrass, needle-and-thread and <br />western wheatgrass decreases, the proportion of blue grams, threeawn, snakeweed and <br />zabbitbrush increases. Undesirable weeds and annual plants invade and become more <br />abueidant as range condition becomes poorer. <br /> <br />