Microbial antagonism in the rhizosphere as a factor in the failure of inoculation of subterranean clover

In an investigation into the cause of poor nodulation of subterranean clover on a yellow podzolic soil the following results were obtained: (1) Failure of seed inoculation was due to microbiological antagonism which prevented normal colonization of the rhizosphere by the bacteria in the applied inoculum. (2) The antagonism was shown to be confined to the clover rhizosphere. (3) Greater rhizosphere populations were obtained by the use of increased rates of inoculation or with normal rates on the sites of log fires. This latter effect was attributed to the presence of charcoal. (4) The technique used for the determination of numbers of nodule bacteria in the clover rhizosphere was found to give an early and reliable evaluation of the success of inoculation.