Evaluation of N2 fixation and agroforestry potential in selected tree legumes for sustainable use in South Africa

Seven tree legumes with agroforestry potential were tested for their capacity to nodulate with indigenous rhizobia or bradyrhizobia in soils collected from different ecological zones in South Africa. Our findings show that all the tested species, except Acacia senegal, could effectively nodulate with root-nodule bacteria native to Venda and Klipspruit soils. Since Acacia seyal, Acacia galpinii, Albizia lebbeck and Acacia auriculiformis exhibited, in that order, a greater level of growth and symbiotic performance, they manifest themselves as suitable species for agroforestry programs in Venda and Klipspruit soils. One indigenous species, Acacia ataxancantha, was assessed to be a non-nodulating legume even when inoculated with a promiscuous strain of Rhizobium NGR234.