This data set is a subset of the data set created by Schwarz and Alexander (1995) that was compiled for the conterminous United States from individual state coverages contained in the October 1994 State Soil Geographic Data Base produced on CD-ROM.
The tabular data in this file contains estimated and measured data on the physical and chemical soil properties, soil interpretations, and static and dynamic metadata. Most tabular data exist in the database as a range of soil properties, depicting the range for the geographic extent of the map unit. In addition to low and high values for most data, a representative value also is included for these soil properties.
MUID Map unit identifier (first two characters are the state abbreviation). This attribute is used to relate this table with 'Soils250K'.
AWC Available water capacity (in inches per inch). Computed as a layer thickness weighted average, across soil layers, of a simple average of awch and awcl contained in the STATSGO layer file. Missing value indicator = -0.1
CLAY Percent of soil consisting of clay (in percent of material less than 2 millimeters in size). Computed as a layer thickness weighted average, across soil layers, of a simple average of clayh and clayl contained in the STATSGO layer file. Missing value indicator = -0.1.
KFFACT Actual k factor used in universal soil loss equation to calculate soil loss by water. Computed as a layer thickness weighted average, across soil layers, of the variable kffact contained in the STATSGO layer file. Missing value indicator = -0.1.
OM Organic material in the soil (in percent by weight). Computed as a layer thickness weighted average, across soil layers, of a simple average of omh and oml contained in the STATSGO layer file. Missing value indicator = -0.1
PERM Permeability of the soil (in inches per hour). Computed as a layer thickness weighted average, across soil layers, of a simple average of permh and perml contained in the STATSGO layer file. Missing value indicator = -0.1
THICK Depth of soil layers (in inches). Computed as the sum of the differences between laydeph and laydepl for each soil layer in the STATSGO layer file. Missing value indicator = -0.1
HYGRP A code identifying the hydrologic characteristics of the soil. The character codes defined in the STATSGO component file are converted into numeric codes. The coding transformations are A = 1 (high infiltration, deep soils, well drained to excessively drained sands and gravels), B = 2 (moderate infiltration rates, deep and moderately deep, moderately well and well drained soils with moderately coarse textures), C = 3 (slow infiltration rates, soils with layers impeding downward movement of water, or soils with moderately fine or fine textures), D = 4 (very slow infiltration rates, soils are clayey, have a high water table, or are shallow to an impervious layer). Mixture codes A/D, B/D, and C/D are assigned the value 4. Also, certain areas were subselected and assigned values for HYGRP based on the area type. Miscellaneous areas (denoted by M in COMPNAME) and labeled as Dumps, and Gullied Land in COMPNAME are assigned the HYGRP = 2.5 if the HYGRP value is missing. Areas denoted as Pits, Rock Outcrops, Terrace Escarpments, and Urban land with missing HYGRP are assigned a HYGRP of 4. See the documentation of the SAS program "setussoils.sas" for additional details. The transformed data are averaged across components using the component percentage as weights. The missing value indicator is -0.1.
DRAIN A code identifying the quality of soil drainage. The two character code from the STATSGO component file is converted to a numeric value according to the following translation: E = 1 (excessive), SE = 2 (somewhat excessive), W = 3 (well drained), MW = 4 (moderately drained), SP = 5 (somewhat poorly drained), P = 6 (poorly drained), and VP = 7 (very poorly drained). The values are averaged across components using the component percentage as weights. The missing value indicator is -0.1.
SLOPE The slope of the map unit (in percent). Slope values contained in the STATSGO component file are averaged using the component percentage as weights. The missing value indicator is -0.1.
LL Liquid limit of soil layer (in percent moisture by weight). Computed as a layer thickness weighted average, across soil layers, of a simple average of llh and lll contained in the STATSGO layer file. Missing value indicator = -0.1.
IFHYDRIC Share of map unit with hydric soils (1 = entire map unit has hydric soils). Computed by summing the component percentage for each component designated as having hydric soils according to the variable hydric in the STATSGO component file. Missing value indicator = -0.1.
AFLDFREQ Annual flood frequency code. Flood frequency designations contained in the variable anflood in the STATSGO component file are converted to numeric codes according to the following translation: 1 = greater than 50 percent, 2 = 5 percent to 50 percent, 3 = 0 percent to 5 percent, and 4 = no flood. Translated variables are averaged across components using the component percentage as weights. The missing value indicator is -0.1.
The NRCS recommends that any maps using NRCS STATSGO data show the source and date, and provide the following statement: "STATSGO is designed to support regional, multistate, state, and river basin resource planning, management and monitoring."
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.