N2 Fixation by Grain Legume Varieties as Affected By Rhizobia Inoculation in The Sandy Loam Soil Of Sudano-Sahelian Zone of North Eastern Nigeria.

Abstract

Rhizobium – legume symbiotic association contributes considerable amount of N in
tropical soils. However, low rainfall and high temperature in Sudano-Sahelian region of Northeastern Nigeria may affect the Rhizobial population in the soil. Therefore, the influence of Rhizobia inoculation on N2 fixation by cowpea (Vigna unguiculata (L.) Walp.), groundnut (Arachis hypogaea L.) and bambara groundnut (Vigna subterranean L.Verdc.) was evaluated under field condition in Maiduguri. The seeds of the crops were inoculated with their Rhizobium strains and grown for 50 days, after which they were harvested and the amount of N fixed was measured. The results showed that rhizobia inoculation increased the amount of N fixed by 46% over the control. Cowpea differed significantly (P<0.05) from groundnut and bambara groundnut. Cowpea fixed 42.68 KgNha-1 while groundnut and bambara groundnut fixed 27.19 and 32.53 KgNha-1, respectively. Cultivation of Bornoji red cowpea variety inoculated with Rhizobium will alleviate soil N level.