USGS Open-File Report 2004-1227

Data dictionary for file 'horiz01', S3C Database, Version 20040427
[USDA, United States Department of Agriculture; NRCS, Natural Resources Conservation Service; STATSGO, State Soil Geographic; SSURGO, Soil Survey Geographic; VARIABLE FORMAT--Dw.d, where D=data type (C, character; F, floating point; I, integer), w=field width, d=precision; %, weight percent; cm, centimeter; mm, millimeter; g cm^-3, grams per cubic centimeter; kg m^-2, kilograms per square meter; SU, standard pH unit; SOC, soil organic carbon.]
VARIABLE NAME	VARIABLE FORMAT (Dw.d)	DEFINITION	UNITS
pedkey	C16	Combination of 'source' and 'idped'. Primary key ('pedon01' table) linking pedon and horizon ('horiz01' table) records.
hznkey	C16	Combination of 'source' and 'idsam'. Primary key ('horiz01' table)--combination of 'pedkey' and 'hznkey'.
source	C4	Origin of dataset used (danl, feld, lasu, nssc, uark, uiuc)^1.
idfips	C5	Concatenation of two letter state abbreviation and county FIPS code.
idped	I9	4-digit calendar year the pedon was sampled * 100000 + a unique pedon identifier.
idsam	I9	4-digit calendar year the horizon was sampled * 100000 + a unique horizon identifier.
horizon	C18	Soil horizon designation^2 as determined by the field investigator.
mhz	C18	Modern equivalent (1997) horizon designation^2,3.
mhzgp	C8	Generalized horizon group^3, primarily based on master-horizon designations. Horizon-group designations are used for data aggregation and statistical analysis.
thdep	F10.1	Depth to top of horizon.	cm
bhdep	F10.1	Depth to bottom of horizon.	cm
sand	F10.1	Weight percent (2 mm base, air-dried sample) of particles >0.05 mm and <2.0 mm diameter in the horizon (USDA system for classification of soils and sample particle-size data)^5,6.	%
silt	F10.1	Weight percent (2 mm base, air-dried sample) of particles >0.002 mm and <0.05 mm diameter in the horizon (USDA system for classification of soils and sample particle-size data)^5,6.	%
clay	F10.1	Weight percent (2 mm base, air-dried sample) of particles <0.002 mm diameter in the horizon (USDA system for classification of soils and sample particle-size data)^5,6.	%
txclfd	C8	Texture class of soil assigned as part of the field description^2,4.
txclps	C8	Texture class of soil based on the percentages of total sand, silt, and clay in the horizon (USDA system for classification of soils and sample particle-size data)^2,4.
bdad	F10.2	Bulk density (2-mm base) of natural clods in the horizon. Clods are air-dried from 24 to 120 hrs at room temperature or overnight at 15-35 °C and then weighed in air to determine clod mass and in water to determine clod volume^5,6.	g cm^-3
bd3	F10.2	Bulk density (2-mm base) of natural clods in the horizon desorbed to 1/3 bar (33 kPa) tension water content^5,6.	g cm^-3
bdod	F10.2	Bulk density (2-mm base) of natural clods in the horizon oven-dried at 105°C^5,6.	g cm^-3
bd3f	I2	Status flag for 1/3-bar bulk density (variable 'bd3'): 0, 1/3-bar bulk density analytically determined; 1, 1/3-bar bulk density equated to median value for that sample's horizon group (variable 'mhzgp') and empirical texture class (variable 'txclps')^3.
bdodf	I2	Status flag for oven-dry bulk density (variable 'bdod'): 0, oven-dry bulk density analytically determined; 1, oven-dry bulk density equated to median value for that sample's horizon group (variable 'mhzgp') and empirical texture class (variable 'txclps')^3.
caco3	F10.2	Weight percent carbonate expressed as equivalent CaCO3 (2 mm base, air-dried sample) calculated from manometric measurements of CO2 evolved from HCl-treated samples^5,6.	%
phh2o	F10.1	pH (2 mm base, air-dried sample) of a 1:1 mixture of soil and distilled water^5,6.	SU
w15ad	F10.2	Weight percent gravimetric water content (2-mm base) of an air-dried sample equilibrated at 15 bar (1500 kPa) tension^5,6.	%
oc	F10.2	Weight percent organic carbon (2-mm base, air-dried sample) in the horizon. Generally, pre-1995 organic-carbon measurements were made by the Walkley-Black method^7; since 1995, most organic-carbon measurements have been made by dry combustion to CO^2 with quantitation by infrared absorption^5,6.	%
ocflag	I2	Status flag for organic carbon (variable 'oc'): 0, organic carbon analytically determined; 1, organic carbon calculated from organic matter (multiplied by 0.58); 2, organic carbon equated to total carbon (in samples with negligible inorganic (carbonate) carbon.
ocmc_3	F10.2	Mass of organic carbon in the horizon interval, calculated from the weight percent of organic carbon (variable 'oc') and the 1/3-bar bulk density (variable 'bd3')^3.	kg m^-2
ocmc_od	F10.2	Mass of organic carbon in the horizon interval, calculated from the weight percent of organic carbon (variable 'oc') and the oven-dry bulk density (variable 'bdod')^3.	kg m^-2
smc_3	F10.2	Mass of soil in the horizon interval, calculated from the 1/3-bar bulk density (variable 'bd3')^3.	kg m^-2
smc_od	F10.2	Mass of soil in the horizon interval, calculated from the oven-dry bulk density (variable 'bdod')^3.	kg m^-2
svsg	I10	Soil volume (whole-soil base) in the horizon depth interval in a unit volume of one square meter one centimeter thick (10000 cm^3). This volume is calculated from the coarse-fragment data for each soil series in the USDA-NRCS STATSGO^8/SSURGO^9 databases. When multiple records exist for a series, median values are used^3. The calculated soil volume is used to adjust mass storage for the rock volume in the soil profile.
1/ danl, Daniels, W.L., Everett, C.J., and Zelazny, L.W., 1987a, Virgin hardwood forest soils of the southern Appalachian Mountains: I. Soil morphology and geomorphology: Soil Science Society of America Journal, v. 51, p. 722-729, or Daniels, W.L., Everett, C.J., and Zelazny, L.W., 1987b, Virgin hardwood forest soils of the southern Appalachian Mountains: II. Weathering, mineralogy, and chemical properties: Soil Science Society of America Journal, v. 51, p. 730-738.
feld, Feldman, S.B., Zelazny, L.W., and Baker, J.C., 1991a, High-elevation forest soils of the southern Appalachians: I. Distribution of parent materials and soil-landscape relationships: Soil Science Society of America Journal, v. 55, p. 1629-1637, or Feldman, S.B., Zelazny, L.W., and Baker, J.C., 1991b, High-elevation forest soils of the southern Appalachians: II. Geomorphology, pedogenesis, and clay mineralogy: Soil Science Society of America Journal, v. 55, p. 1782-1791, or Feldman, S.B. 1989, Taxonomy, genesis, and parent material distribution of high elevation forest soils in the southern Appalachians: unpublished M.S. thesis, Virginia Polytechnic Institute and State University, Blacksburg, VA, Appendix B, or Feldman, S.B., unpublished data, provided to USGS in 2000.
lasu, Schumacher, B.A., Day, W.J., Amacher, M.C., and Miller, B.J., 1988, Soils of the Mississippi River alluvial plain in Louisiana: Louisiana State University Agricultural Center, Baton Rouge, LA, Louisiana Agricultural Experiment Station Bulletin No. 796, 275 p.
nssc, U.S. Department of Agriculture, Natural Resources Conservation Service, 2001, National soil survey characterization data: Soil Survey Laboratory, National Soil Survey Center, U.S. Department of Agriculture, Natural Resources Conservation Service, Lincoln, NE, accessed September 1, 2001 at URL http://ssldata.nrcs.usda.gov/.
uark, University of Arkansas, 2000, unpublished data, Soil Characterization Laboratory, Fayetteville, AR, provided to USGS, 1999-2000.
uiuc, University of Illinois, 2001, Soil Characterization Database, Soil Characterization Laboratory, Urbana-Champaign, IL, accessed February 15, 2001, at URL http://www.il.nrcs.usda.gov/technical/soils/soil_lab.html.
2/ Schoeneberger, P.J., Wysocki, D.A., Benham, E.C., and Broderson, W.D., 1998, Field book for describing and sampling soils: U.S. Department of Agriculture, Natural Resources Conservation Service, National Soil Survey Center, Lincoln, Nebraska, 177 p.
3/ Buell, G.R. and Markewich, H.W., in press, Data compilation, synthesis, and calculations used for organic-carbon storage and inventory estimates for mineral soils of the Mississippi River basin, chap. A of Markewich, H.M., ed., Soil-carbon storage and inventory for the continental United States: U.S. Geological Survey Professional Paper 1686.
4/ Soil Survey Staff, 1993, Soil survey manual, 2nd ed.: U.S. Department of Agriculture, Natural Resources Conservation Service, National Soil Survey Center, Soil Survey Laboratory, Lincoln, NE, Agriculture Handbook 18, 410 p.
5/ Soil Survey Staff, 1995, Soil survey laboratory information manual: U.S. Department of Agriculture, Natural Resources Conservation Service, National Soil Survey Center, Lincoln, NE, Soil Survey Investigations Report No 45, version 1, 305 p.
6/ Soil Survey Staff, 1996, Soil survey laboratory methods manual: U.S. Department of Agriculture, Natural Resources Conservation Service, National Soil Survey Center, Lincoln, NE, Soil Survey Investigations Report No. 42, Version 3, 693 p.
7/ Walkley A., 1935, An examination of methods for determination of organic carbon and nitrogen in soils: Journal of Agricultural Science, v. 25, p. 598-609.
8/ U.S. Department of Agriculture, Natural Resources Conservation Service, 2001, State Soil Geographic (STATSGO) Database, accessed September 1, 2001, at URL http://www.ncgc.nrcs.usda.gov/branch/ssb/products/statsgo/index.html.
9/ U.S. Department of Agriculture, Natural Resources Conservation Service, 2001, Soil Survey Geographic (SSURGO) Database, accessed September 1, 2001, at URL http://www.ncgc.nrcs.usda.gov/branch/ssb/products/ssurgo/index.html.

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