A Gram-negative, non-motile, pale-yellow, rod-shaped bacterial strain, DS-42(T), was isolated from a soil in Korea and its taxonomic position was investigated by a polyphasic study. Strain DS-42(T) grew optimally at 25 degrees C and pH 7.0-8.0. Strain DS-42(T) did not form nodules on three different legumes, and the nodD and nifH genes were also not detected by PCR. Strain DS-42(T) contained Q-10 as the predominant ubiquinone. The major cellular fatty acid was C(18 : 1)omega7c. The DNA G+C content was 60.8 mol%. Phylogenetic analyses based on 16S rRNA, atpD and recA gene sequences showed that strain DS-42(T) belonged to the genus Rhizobium. Strain DS-42(T) showed 16S rRNA gene sequence similarity of 94.1-97.7 % to the type strains of recognized Rhizobium species. DNA-DNA relatedness between strain DS-42(T) and the type strains of Rhizobium huautlense, R. galegae, R. loessense and R. cellulosilyticum was 13-19 %, indicating that strain DS-42(T) was distinct from them genetically. Strain DS-42(T) can also be differentiated from these four phylogenetically related Rhizobium species by various phenotypic properties. On the basis of phenotypic properties, phylogenetic distinctiveness and genetic data, strain DS-42(T) is considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium soli sp. nov. is proposed. The type strain is DS-42(T) (=KCTC 12873(T) =JCM 14591(T)).