Contribution of biological nitrogen fixation towards the African food and environmental challenges

Abstract

Efforts to increase food production for the rising population in Africa can benefit from the large pool of information on biological nitrogen fixation (BNF). The continued rise in the cost of chemical fertilisers and their unavailability to farmers have further propelled the quest for viable BNF technologies. Successes in BNF, especially the establishment of inoculant production in several countries in Africa is seen as a major step in the right direction. Similarly the acceptance of well nodulated legumes such as soybean, Leucaena, and the Frankia-nodulated plants like Casuarina provides positive bases for BNF demonstrations. Due to Africa’s rich biodiversity, potential exists for exploiting newer plants and development of stress-tolerant plant hosts and their microsymbionts. Positive results on limited mycorrhiza-Rhizobium co-inoculation which alleviates phosphorus deficiency while facilitating N2 fixation ought to be supported. At the same time, the search for acid-tolerant Rhizobium strains should be intensified. Many studies on response to inoculation have gained from regionally coordinated trials and a model which is now available to predict such response is likely to augment field studies provided chemical soil data is available. The need for an increased knowledge base on Azolla, Cyanobacteria and Frankia to augment the Rhizobium system is emphasised. Similarly soil management strategies aimed at improving soil fertility employing current BNF methodologies are examined. Further the need for broad host range Rhizobium strains, costing of BNF, and field demonstrations of BNF are discussed