Evaluation of Biological Nitrogen fixation by faba bean [vicia faba L.] plants using N-15 dilution techniques

ABSTRACT

A greenhouse experiment was carried out to evaluate BNF by faba bean using 15N dilution technique. Three cultivars of labs bean i.e. Giza 2, Giza 461 and Rentablanka were used as N-fixing crops, wheat [Sakha 69] was used as a reference crop. Uninoculated and inoculated seeds with Rhizobium and/or VAM were sown in sandy soil unattended with labeled 15NH4N03 [15 kg N/fed, 4.68% 15N a.e.] or 15N rice straw [0.2 o w/w, 1.63% 15N a.e.]. Rock-P was added as a source of P at rate of 20 kg P/fed. Generally, from the economical and environmental point of view, application of N2 fixers and vesicular arbuscular mycorrhizal fungi in combined inoculants for legumes can save about 80% of N and 50% of P fertilizers. The use of organic N source as slow release fertilizer in virgin uncultivated and unreclaimed soil in Egypt speeds up the biological activity of these soils