The FIFE Root Biomass data were collected from 16 locations within the FIFE study area during the 1987 growing season. They provide a measure of the below-ground biomass for the study area. Biomass reported as grams per square m assumes that the depth of the core samples is sufficient to include all root biomass under the surface to an infinite depth. Prairie vegetation does possess roots deeper than the 20 cm coring, however, the fraction of total root biomass below 20 cm is minuscule and safely ignored in a study of biomass.