Agriculture has benefited from biological nitrogen fixation through the activity of obligate and facultative endophytic microorganisms, but less from the action of free fixers living in the rhizosphere. However, organic fertilizers enriched with nitrogen-fixing heterotrophic microorganisms have recently appeared on the market, seeking to promote fixation by placing the microorganisms close to the food substrate. The aim of the work was to evaluate the effect of fertilizer treatments on two successive crops of lettuce (Lactuca sativa L.) during the spring/summer period of 2015, followed by the cultivation of red cabbage (Brassica oleracea var. acephala) and turnip greens (Brassica rapa L.) in early autumn.