Influence of Bovine Slurry Deposition on the Structure of Nodulating Rhizobium leguminosarum bv. viciae Soil Populations in a Natural Habitat.

The population of nodulating R. leguminosarum bv. viciae in soil from a grass-covered valley area which had been used for bovine slurry deposition over a period of 5 years was analyzed. For these studies, a rapid and reproducible method based on enterobacterial repetitive intergenic consensus (ERIC)-PCR was applied to identify Rhizobium strains which had infected pea nodules. Soil samples were taken from different areas and further analyzed in plant tests to determine the impact of the application of slurry (polluted or nonpolluted), the slope position (summit or toe), and exposure (north or south). After comparison of all PCR fingerprint patterns, 24 strain groups were defined. Some strain groups from the nonpolluted soil were suppressed in the polluted samples, and new strain groups were detected in the slurry-polluted soil. After analyzing relationships between the strain groups, we determined the influences of local factors on the nodulating R. leguminosarum bv. viciae population. We show that one of those local parameters, slope position, had significantly greater impact on the composition of the Rhizobium population than the presence of slurry.