This paper describes research to create a national database of switchgrass supply as part of the biomass program launched by the Department of Energy. The paper provides an estimate of county level switchgrass yield data for the state of Oklahoma. The estimates are made for the top five most productive and abundant soils for each county in Oklahoma. A simple approach of ratio calculation and estimation is used to predict the switchgrass yield of one soil type by comparing it with the yield of several other crops in another soil type. The data for switchgrass yield for a particular soil type are obtained from the state research experiment stations. The yields for other crops for the top five soils are obtained from the NASS data sources. Switchgrass supply for Oklahoma was estimated to be 49.5 million tons from the top soils with the Northeast crop reporting district to be the dominant supplier.