Influence of biosolids compost on the bradyrhizobial genotypes recovered from cowpea and soybean nodules

The interaction of biosolids compost application to soil and bradyrhizobial genotypes recovered from nodules was examined. Among 170 isolates, seven genotypes were recovered from soils receiving either no biosolids application or rates of 73 or 146 Mg/ha for three successive years. With the exception of one genotype, the distribution of the bacterial genotypes recovered from nodules was interrelated with the level of biosolids. Two of the genotypes nodulated both soybean and cowpea. Because soybean-nodulating bradyrhizobia were not recovered from control plots, it is possible that they had been introduced together with the biosolids compost application.