Rhizobia populations and Soybean yield response to Legumefix inoculant and isolated effective rhizobia strains from Uyole, Kilosa and Mkuyuni soils in Tanzania

Abstract

A study on yield response of soybeans (Glycine max L. Merrill) to Legumefix inoculant and enumeration of rhizobia from soybean growing soils was conducted in the laboratory and the screen house of the Department of Soil Science at Sokoine University of Agriculture. Laboratory analysis revealed that the soils were moderately fertile with textural classes varying from sandy clay loam to sandy loam, hence suitable for soybean production. Rhizobial populations determined by most probable number (MPN) plant infection techniques were 450, 200 and 680 CFU g^-1 soil for Uyole, Kilosa and Mkuyuni soils, respectively. The pot experiment testing soybean nodulation and yields for each soil was conducted in the screen house involving five treatments, namely: i. Control, ii. Legumefix inoculant, iii. 30 kg P ha^-1, iv. 30 kg P ha^-1 + Legumefix and v. 30 kg P ha^-1 + 60 kg N ha^-1 in CRD with three replications. Results revealed that all treatments produced significant (P?0.05) differences on soybean nodulation and yields in all the three soils. Soybean growing soils should be tested for the presence and populations of indigenous rhizobia so as to determine the need for inoculation with introduced rhizobial strains.