**4.8 Role of legume vegetation in improving the soil N pool**

Nitrogen is vital for the crop growth, solely to water and light. However, most vegetation depend on the consumption of soil N to meet their needs; most highly the legumes, are capable of N-fixation with the symbiotic relationship with rhizobia. The BNF benefits not only the legumes however also improves yield in succeeding crops, in agroforestry systems, and in legume-cereal intercropping system. The N quantity made available to cereal crop derives from the breakdown of legume-biomass residues. However, the affiliation of N tends to cross from crop containing enormously high N (i.e., legumes) to those with an increased N demand (nonlegume). An approach to raise N supply in cropping structures is the inclusion of N-fixing leguminous crops, which can grant N advantages to the vegetation thru N transfer. The extent of biologically fixed N/year by way of legumes varies significantly from zero to several hundred kg N/ha.
