The ORNL DAAC has released a data set entitled "Global Gridded Surfaces of Selected Soil Characteristics (IGBP-DIS)." The data surfaces were generated by the SoilData System, which was developed by the International Geosphere-Biosphere Programme (IGBP) Data and Information Services (DIS).
The data set contains separate gridded surfaces of soil-carbon density, total nitrogen density, field capacity, wilting point, profile available water capacity, thermal capacity, and bulk density. The surface grids have a 5 x 5 arc-minute resolution and are formatted in ASCIIGRID for ARC INFO.
For further information about the data set and other soil data maintained by the ORNL DAAC, visit the Soil CollectionsWeb page.