The SSURGO data has minimum and maximum values in addition to a representative value for each soil property measurement (SSURGO, 1995).
The large range between the low and high estimates for the soil carbon storage (Table 2) reflects the variability between the minimum and maximum attributes for individual soil types in the SSURGO database.
CONTENTS (TONS) PARTS DATA SOURCES (95% CONFIDENCE INTERVAL) Standing forest FIA 75,840,970 (48,301,730-103,380,200) Shrub Lookup table 1,575,040 (0-5,543,720) DDW and forest FIA DDW 15,116,800 floor inventory data and (2,821,760-27,411,830) model calculation Soil organic carbon SSURGO 72,971,140 (45,957,970-99,984,310) Root biomass carbon 7,342,650 (0-15,911,580) Total 172,846,600 (131,271,770-214,421,420) Figure 5.
In support of internal NRCS and USDA business requirements and the National Spatial Data Infrastructure, NRCS is working to complete SSURGO for much of the nation within a five-year period.
Data meeting SSURGO specifications are the most detailed and consistently mapped soil resource information for the United States.