1988-04-29_PERMIT FILE - C1981008A (53)

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APPENDIX 9-5-2 (Cont.) Soil Interpretations FOOTNOTES 6 Available Water Holding Capacity (AWHC): the relative amount of water that a soil, from 0-60 inches or to a paralithic or lithic contact, can hold available for use by plants. Affected by such characteristics as soil texture, depth, structure, salts, and organic matter. AWHC modifiers are site-specific for the sampled soil profiles. Class criteria is taken from USDA-SCS, May 1981, Wyoming Soil Interpretation Procedure Guide, pg. 31 and Soil Survey Manual, pg. 4-33. Classes are: Very Low: 0-3 inches; Low: 3-6 inches; Moderate: 6-9 inches; High: greater than 9 inches. 7 Rate of Runoff: This indicates the relative rate that water is removed by flow over the surface of the soil. Classes are defined in the Soil Survey Manual. pg. 4-34 and 4-35. 8 Typical Reaction Class: narrative range of pH of surface (A horizon)/subsoil (B horizon, or if B is lacking, the first C horizon). Slightly Acid and Acid: 6.5 and less; Neutral: 6.6-7.3; Mildly Alkaline: 7.4-7.8; Moderately Alkaline: 7.9-8.4; Strongly Alkaline: 8.5-9.0; Very Strongly Alkaline: greater than 9.0 Soils that are mildly alkaline usually are calcareous. Soils of moderate alkalinity or stronger are assumed to be calcareous. Strongly alkaline soils have 00 increased sodium concentrations. 9 Wind Erodibility Group: This is an arbitrary grouping of soils based on texture and aggregation. Values range from 1 to 8, with lower numbers indicating increased susceptibility to wind erosion. The Wind Erodibility Group classification is for the surface layer only, but could be applied to any layer within a soil profile. Classes are defined in the National Soils Handbook (430-VI-NSH, July 1983, pg. 603-37), and USDA-SCS, May 1981, Wyoming Soil Interpretation Procedure Guide, pg. 35. WEG Soil Texture of Surface Layer Very High Erodibility 1 Very fine sand, fine sand, sand, or coarse sand 2 Loamy very fine sand, loamy fine sand, loamy coarse sand CD High Erodibility 3 Very fine sandy loam, fine sandy loam, sandy loam, or coarse sandy loam N' 4 Clay, silty clay, noncalcareous clay loam, or silty clay loam with more than 35 percent clay content CD 4L Calcareous loam and silt loam, or calcareous clay loam, and silty clay loam o Medium Erodibility 5 Noncalcareous loam and silt loam with less than 20 percent clay content, sandy clay loam, or sandy clay 6 Noncalcareous loam and silt loam with more than 20 percent clay content, or noncalcareous clay loam with less than 35 percent clay content Low Erodibility 7 Silt, noncalcareous silty clay loam with less than 35 percent clay content 00 8 Soils not suitable for cultivation due to coarse fragments or wetness, wind erosion not a problem