Biological Nitrogen Fixation on Legume

Nitrogen (N) is one of the major limiting factors for crop growth and is required in adequate amount, due to its function as protein and enzyme components. In general, plants need sufficient nitrogen supply at all levels of growth, especially at the beginning of growth phase. Therefore, the availability of less expensive N resources would reduce the production cost. The increasing  use  of  chemical  fertilizer  would  probably  disturb  soil  microorganisms,  reduce  the  physical  and  chemical characteristics of soil because not all of N based fertilizer applied can be absorbed by the plants. Approximately only 50% can be used by crops, while the rest will be altered by microorganism into unavailable N for crops or else dissappear in the form of gas. Leguminous crops have the capacity to immobilize N2  and convert into the available N if innoculated with Rhizobium . The amount of N2 fixed varies depending on legume species and their environment. Key words: Nitrogen fixation, legume