Explanation:

Biological nitrogen fixation is the process that changes inert N2 to biologically useful NH3 (not nitrate). This process is mediated in nature only by bacteria. Other plants benefit from nitrogen fixing bacteria when the bacteria die and release nitrogen to the environment, or when the bacteria live in close association with the plant. In legumes and a few other plants, the bacteria live in small growths on the roots called nodules. Within these nodules, nitrogen fixation is done by the bacteria, and the NH3 produced is absorbed by the plant. Nitrogen fixation by legumes is a partnership between a bacterium and a plant. All plants can’t do it, only leguminous plants can.