Populations of Bradyrhizobium japonicum in Fields Cropped with Soybean‐Rice Rotations

Abstract

Abstract The population density of Bradyrhizobium japonicum in soil, before planting, largely determines the potential yield increase of soybean ( Glycine max L. Merrill) due to inoculation. Soybean is cultured in rotation with rice ( Oryza sativa L.) in the paddy rice belt of the southern USA. Nineteen fields were sampled to determine the influence of paddy rice culture on the population of B. japonicum . Populations in fields following soybean were approximately 1 × 10 4 bradyrhizobia g −1 soil. Growing rice after soybean did not reduce the population of bradyrhizobia. Apparently the bradyrhizobia were able to survive the conditions in saturated soil for several months.