Two common bean cultivars were grown in a low nitrogen (N), stubble field with and without Rhizobium inoculation. Four rates of nitrogen fertilizer were applied. In addition, double enriched ammonium nitrate (10% atom excess) was used in microplots to estimate percentage nitrogen derived from the atmosphere (%Ndfa). Increased rates of N fertilizer resulted in increased plant height and yield and decreased %Ndfa. Inoculation of bean with granular Rhizobium inoculant enhanced N, fixation and improved seed yield.