Files for bulk density

Data set reference code -- 1996-0128

To accommodate users with a variety of GIS software, the data giving the bulk density are available in several different formats. The files needed by each of the types of user below are described separately.

NOTE -- Most of these files have been compressed using the GNU gzip program, as indicated by the .gz file extension. Users who do not have access to the gunzip decompression program can request that files be uncompressed prior to transfer via ftp. In some cases, however, the uncompressed file may be very much larger than the compressed version, greatly increasing file transfer time.

Arc/Info polygon file users

The orginal STATSGO mapunits for the 48 states have been merged into a single Arc/Info polygon (vector) coverage. The bulk density for each standard layer of each mapunit is given by the INFO table MU_BD, which may be RELATEd to the mapunit coverage using "MUID" as the relate item. The needed files are

mu_poly.e00.gz (101 Mbyte, uncompresses to 269 Mbyte)
Mapunit polygon coverage in Arc/Info EXPORT format.
mu_bd.e00.gz (264 kbyte, uncompresses to 1.3 Mbyte)
INFO table giving mean bulk density for each standard layer of each mapunit, in Arc/Info EXPORT format.
stdlayer.e00
INFO table defining the 11 standard soil layers for which the mean bulk density was computed.

Arc/Info grid file users

The mapunits have been gridded at 30-arcsec cell size. The value attribute table (VAT) for the Arc/Info grid listed below contains the mapunit indentifier, MUID, the mapunit serial number, MUSERIAL, the mean depth to bedrock, ROCKDEPM, and the mean bulk density for each of the 11 standard soil layers.

Warning -- The uncompressed version of the grid file below is very much larger than the compressed version.

bdgrid.e00.gz (10.6 Mbyte, uncompresses to 192 Mbyte)
30-arcsec grid giving bulk density, in Arc/Info grid format.
stdlayer.e00
INFO table defining the 11 standard soil layers for which the mean bulk density was computed.

Other users of gridded data

The 30-arcsec gridded data are also available as a three-dimensional array of 16-bit unsigned binary integers, where each integer value represents the bulk density multiplied by 100. The data are organized as eleven two-dimensional layers, giving, respectively, mean BD for each of the 11 standard soil layers. Within each layer, the values are arranged by horizontal rows. All values for the first layer are given first, starting with the value for the left (western) end of the top (northern-most) row, and continuing left to right along the row. The data for the last row of the first layer are then followed by the top row of the second layer, and so on.

The array contains 11 layers each containing 2984 rows of 6936 values. Code for reading the binary array is available in Fortran 77 and C.

Warning -- The uncompressed version of the BSQ file below is very much larger than the compressed version.

bd.bsq.gz (26 Mbyte, uncompresses to 455 Mbyte)
Three-dimensional array of 16-bit unsigned integer values for mean bulk density for each standard layer of each grid cell.
stdlayer.ascii
Table defining the 11 standard soil layers for which the mean bulk density was computed.
The same array is also available in LAS format (files bd.img.gz and bd.ddr).

Local users on the ESSC network

The file systems containing the datasets are cross-mounted on the local ESSC computer network. Local Arc/Info users may find it more convenient to copy necessary files directly to their own workspaces using the Arc/Info COPY and COPYINFO commands. The needed directories and files (under directory $DSREF/1996-0128/) are
bdgrid
Arc/Info grid giving mean bulk density for each standard soil layer for each 30-arcsec grid cell.
../mapunits/mu_poly
Arc/Info coverage containing polygon version of mapunit boundaries.
info!MU_BD
INFO table giving bulk density values for each mapunit.
info!STDLAYER
Table defining the 11 standard soil layers for which the mean bulk density was computed.
Last change: 2006 Apr 14, R. A. White / raw@essc.psu.edu