ENHANCING LEGUME N-2 FIXATION THROUGH PLANT AND SOIL-MANAGEMENT

Atmospheric N-2 fixed symbiotically by associations between Rhizobium spp. and legumes represents a renewable source of N for agriculture. Contribution of legume N-2 fixation to the N-economy of any ecosystem is mediated by: (i) legume reliance upon N-2 fixation for growth, and (ii) the total amount of legume-N accumulated. Strategies that change the numbers of effective rhizobia present in soil, reduce the inhibitory effects of soil nitrate, or influence legume biomass ail have potential to alter net inputs of fixed N. A range of management options can be applied to legumes growing in farming systems to manipulate N-2 fixation and improve the N benefits to agriculture and agroforestry.