A series of solution culture experiments designed to simulate some field conditions were carried out with varieties (Carioca, Rico 23 and Venezuela) in order to check the hypothesis that adverse soil factors might affect N fixation. The main conclusions were the following: (1) growth was promoted by increasing the level of combined N; only the starter rates (from 0.3 to 1.3 mM/l), however, promoted nodulation and dinitrogen fixation; (2) higher dry matter production was observed at pH 6.0 to 7.0, whereas poor growth at pH 4.0 could be traced to low N2 fixation; (3) a favourable effect of Ca supply on the parameters under study was observed up to the level of 1.25 mM/l; (4) a linear response to P supply was verified; (5) excess Al and Mn (5-10 ppm; 10-20 ppm; respectively) caused inhibition on nodulation, reduction on root growth and N2 fixation; (6) although the trends were the same, varietal differences were found.