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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.] |
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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 designation2 as determined by the field investigator. |
|
mhz |
C18 |
Modern equivalent (1997) horizon designation2,3. |
|
mhzgp |
C8 |
Generalized horizon group3, 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 description2,4. |
|
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
volume5,6. |
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 content5,6. |
g cm-3 |
bdod |
F10.2 |
Bulk density (2-mm base) of natural clods in the horizon oven-dried at
105°C5,6. |
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 samples5,6. |
% |
phh2o |
F10.1 |
pH (2 mm base, air-dried sample) of a 1:1 mixture of soil and
distilled water5,6. |
SU |
w15ad |
F10.2 |
Weight percent gravimetric water content (2-mm base) of an air-dried
sample equilibrated at 15 bar (1500 kPa) tension5,6. |
% |
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 method7;
since 1995, most organic-carbon measurements have been made by dry combustion
to CO2 with
quantitation by infrared absorption5,6. |
% |
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 cm3). This volume is
calculated from the coarse-fragment data for each soil series in the
USDA-NRCS STATSGO8/SSURGO9 databases. When
multiple records exist for a series, median values are used3. The calculated soil volume is used to
adjust mass storage for the rock volume in the soil profile. |
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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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