In order to reduce the quantities of chemical fertilizers based on nitrogen as well as the environmental pollution, the attention was oriented to the atmospheric nitrogen fixation processes which has a great importance and it is a viable alternative to supply the vegetables with this important element and which will have a benefic effects on the vegetable cultures. In Arad agro-ecological area between 1997 and 2001 were conducted a range of experiments on the garden sowing bean cultures. The doses of nitrogen fertilizers ranged between 30 and 120 kg active substance per hectare. The bacterial product used to treat the bean seeds was Biotrofin (10l/ha), product that has two living components: a nitrogen fixating bacteria, that gets its nitrogen from the atmosphere and a second bacteria, Bacillus megaterium, that dissolves the tri-calcium phosphate rendering it accessible to the plants. The experiment was carried out for 4 years and he had three different graduated factors, organized in squares subdivided with three repetitions, variety Valja, the surface of a square for the repetition being of 15 sq meters. The evaluation of the results was performed by the method of variants analysis for multi-annual experiments carried out in the same location. The average maximal effect over the experimenting cycle (2,246 t/ha) of the various applied doses of nitrogen fertilizers in correlation with the bacterization and the controlled soil humidity corresponds to the N60 fertilization variant. The indexes that contribute to the increase of the yield with the said amount at N60 correspond to the bacterized seeds and mostly on irrigation conditions. At the average value of N30 the effects of nitrogen are increasing towards the maximum especially for the irrigated cultures. The further increase of the nitrogen doses to 90 or 120 kg/ha causes a decrease of the yield with an obvious contribution lack from the bacterization. The number of nodosities determined, both total and active is increasing during vegetation, the maximal value being at R4 stage (the beginning of pods forming). In R2 (vegetative phase) the nodosities are found mostly on the main root while during the following stages also on the secondary roots. According to the data nitrogen doses higher than N60 break the photosynthetic processes being obvious the numerical decrease of the nodosities as well as their weight and activeness. The findings after the complex analysis of the three studied factors show the benefic effect of bacterization with Biotrofin (10 l/ha) on irrigation basis and a moderate use of nitrogen fertilizers (30-60 kg/ha).