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TABLE 9-2-2 IContinuedl 'Slope Classes are: A = 0.5%; B = 5-10%; C = 10-15%; D = 15-30%; F = 5070%. Slope classes are definetl in SCS 119811. 'Texture of Control Section: as definetl in SCS 119751. The textural control secuon Is generally the upper 20 inches or the whole of an argillic horizon or from 10-40" or bedrock, whichever Ia shallower; or the whale soils if bedrock Is 14' deep or lass. 'Depth: raters to the soil prolila depth before encountering bedrock or a paralithic contact. Depth classes are delined in SCS 119611. Depth Class Inches Vary Shallow lass than 10 Shallow 10-20 Moderately deep 2040 Deep 40-60 Very Deap 60+ 'Major flootinp Depth: tlepth to which the majority of plant roots ware phserved to occur. 'Internal Drainage: refers to aeration or saturation characteristics within the soil prolila. Well drained soils allow water to move through the profile reatlily but not rapitlly, antl soil aeration is typically tlroughty, sandy, and poorly developed. Somewhat poorly tlralned soils have a wet state relatively high in the profile for a significant length of nme to impede most uses, unless artificially drained. Poorly tlralned soils commgnly are wet at or near the surface during a consitlerable pan of the year. Drainage classes are delined In SCS 119611. 'Permeability: Permeability Is a characteristic of soils which relatetl to the movement pf water through the profile. Permeability criteria era basetl on the rate at which water moves through the most slowly permeable layer to a tlepth of 60 inches in a saturated soil profile. Permeability classes are definetl In SCS 119831. Permeability Class Rate )inches/hour) Typical soil Texture Very slow Slow Moderately slow Moderate Motlerataly rapid Rapitl Very rapid less than 0.06 0.06 ~ 0.2 0.2 - 0.6 0.6 - 2.0 2.0 - 6.0 fi.0 - 20.0 More than 20 C, SC, antl SIC CL+, SiCL CL, Sil L, Vfsl, antl SCL SL, LS GLS, 5, an dG G 'Available Water Holding Capacity IAWHCI: the relative amount of water that a soil, form 0-60 inches gr to a paralithic or lithic contact, can hold available for use by plants. Altacted by such charactarisllcs as soil Texture, depth, structure, salts, and organic matter. AWHC modifiers era site-specific for the sampletl soil profiles. Class criteria Is taken from USDA-SCS 119611 and SCS 119871. Classes are: Very Low: 0~3 Inches: low: 3~6 inches; Moderate: 6-9 Inches; High: 9-12 Inches: Very High: greater than 12 Inches). 'Rate of Runoff: this indicates the ralalrve rate that water is ramavatl by Ilow over the surface of the soil. Classes are definetl in the SCS, 1981. 'TVpical Reaction class: Narrative range of pH in entire profile pf surface IA horizon)/subsoil IB horizon, or it B iz lacking, the test C horizon). Siron9ly Acld: 5.5 antl less: Moderately Acitl: 5.fi-6.0; Slightly Acitl: 6.1-6.5; Neutral: 6.6-6.7; Mildly Alkaline: 7.4-6; Moderately Alkaline: 7.0-6.4; Strongly Alkallna: 6.5-9.0: Reaction classes are definetl In SCS 119811. Soils that are mildly alkaline usually are calcareous. Soils of moderate 9lkalinlty or stronger are assumed Io be calcareous. Strongly alkaline soils have increasetl sodium concentrations. 1OWind Eradibility Group: this Is an arbitrary grouping of soils based gn texture antl aggregallon. Values range from 1 Io 8, with lower numbers Indurating increasetl susceDhbility to wlntl erosign. The WInO Erodi61lity Group classifications for the surface layer only, but could be applied to any layer within a soil profiled. Classes ere defined in SCS 119831 and USDA-SCS 119611. WEG Soil Taxtura of Surface Laver Very High Erodlbility 1 Very line sang fine sand, and, or coarse sand 2 Lpamy vary line send, loamy fine santl, loamy coarse sand High Erodiblllty 3 Very line sandy loam, fine sandy loam, sandy loam, or coarse sandy loam 4 Clay, silty clay, noncalcareous clay loam, or silty clay loam wlih more than 35 percent clay cgntent 4L Calcareous loam and silt Ipam, or calcareous clay loam, end silty clay loam TABLE 9-2-2 ICOntinuetll 9-2-7 Revised 9/98