County-level Cropland Carbon Estimates for the
Tristram O. West
Environmental Sciences Division,
uptake by crops in 2005 in the contiguous
Net Primary Productivity (NPP) for croplands can be
estimated using a statistical method that includes factors for dry weight,
harvest indices, and root:shoot ratios multiplied by yield data from the
National Agricultural Statistics Service (NASS). This method has been documented and published
by Prince et al. (2001), Hicke and Lobell (2004), and Hicke et al. (2004). We expanded this method by including factors
for more crops and by using carbon content for agricultural crops (Brady and
Weil, 1996) to estimate (a) total net carbon uptake, (b) carbon in aboveground biomass,
(c) carbon in belowground biomass, (d) carbon harvested and transported off
site, and (e) the amount of carbon remaining on the surface following
harvest. These five variables are
included with their respective Federal Information Processing Standards (FIPS)
codes for all counties in the contiguous
Users of these data are encouraged to read papers cited above and listed in the reference section. These papers provide information on the initial collection and analysis of USDA-NASS data and on data gaps and potential errors in the NASS data.
Data are provided in two file formats. A comma-delimited format (CSV) is provided for use with common spreadsheet software. An ArcGIS shapefile (SHP) is provided for spatial delineation of the county data within GIS software. Shapefiles consist of six separate files, all of which are provided as a single ZIP file. WinZip may be used to extract these files.
Hicke, J.A. and
D.B. Lobell. 2004. Spatiotemporal patterns of cropland area and net primary
production in the central
Hicke, J.A., D.B. Lobell, and G.P. Asner. 2004. Cropland area and net primary production computer from 30 years of USDA Agricultural Harvest Data. Earth Interactions 8, Paper No. 10.
Prince, S.D., J. Haskett, M. Steininger, H. Strand, and R. Wright. 2001. Net primary production of U.S. Midwest croplands from agricultural harvest yield data. Ecological Applications 11(4): 1194-1205.