A pot experiment in the greenhouse was conducted using isolineas D71.93.20 (nodulating) and D71.93.31 (non-nodulating) to study the effect of nitrogen application as side dressing on the dry matter yield at flowering time and seed yield. The treatments consisted of 1) D71.93.30 + inoculante, 2) D71.93.30 + inoculante + N; 3) D71.93.31 and 4) D71.93.31 + N. The nitrogen was applied at the rate of 50 kg/ha of N in the form of ammonium sulphate. The results showed that there were no big differences in the production of dry matter harvested at the time of flowering but the seed production in D71.93.31 was greatly affected by nitrogen deficiency even when nitrogen was side dressed. In D71.93.30 which nodulate there was no response to N applied as side dressing, which was confirmed by concentration of N observed in leaves, seeds and seed yield.