Spread of Rhizobium and Bradyrhizobium in soil

Abstract

Movement of Rhizobium loti and Bradyrhizobium sp., from established Lotus corniculatus and L. pedunculatus respectively, was studied to determine if lack of root-nodule bacteria would limit nodulation following natural reseeding. High populations of root-nodule bacteria occurred in the soil under established plants. However, movement away from established plants varied with topography. Downslope movement was most rapid, but did not exceed 4.0m yr −1. Lateral movement was very low at <0.25 m yr −1. Few root-nodule bacteria were detected even 1 m upslope from established plants 5 yr after sowing, indicating little movement in wind-blown dust or on the hooves of grazing animals. When assessing the feasibility of natural reseeding, maximum rates of spread of root nodule bacteria of <0.25 and 4.0m yr −1 laterally and downslope respectively should be expected.