A study was conducted on short grass prairie near Fort Collins Colorado to determine the effect of depth, slope and micro-relief (ridges and depressions) on belowground biomass. The underground plant biomass was collected to 40cm depth. Fifty percent ( 1004 g/m2 ) of the total collected biomass (2008g/m2) was found in the 0-10cm soil section; 24%(482 g/m2) in the 10-20cm layer; and 26%(522 g/m2) in the 20-40cm depth. The middle slope out-produced (2370g/m2) the upper slope (1741g/m2) and lower slope (1911g/m2) in root biomass. The belowground production of ridges (2064g/m2) was not significantly different from that of the depressions (1951g/m2). This showed that the bulk of root system in short grass prairie ecosystem was close to the ground surface.