Nitrosomonas’ bacteria in the root modules of leguminous plants converts nitrogen gas from air into inorganic nitrogen compounds which enrich the soil and can be readily used by plants. Multiple cropping with legumes can thus significantly reduce the need for_______

Leguminous plants host nitrogen-fixing bacteria (like Rhizobium, not Nitrosomonas which are nitrifying bacteria) in root nodules that convert atmospheric N2 into ammonia. When legumes are multiple-cropped, they naturally replenish soil nitrogen, significantly reducing the need for synthetic nitrogen fertilizers. Note: the question incorrectly names Nitrosomonas, but the concept remains correct.