Legume Response to Rhizobial Inoculation in the Tropics: Myths and Realities

The myth that legumes do not respond to inoculation in the tropics is supported by general misconceptions about the promiscuity of tropical legumes and the ubiquity and abundance of tropical rhizobia. In reality, tropical legumes often exhibit some degree of specificity in their rhizobial requirements. Specifically, the response to inoculation will be primarily controlled by the size and effectiveness of indigenous populations of rhizobia, and, to a lesser extent, by the yield potential of the crop and the availability of N from the soil. Because the legume response to rhizobial inoculation involves a complex interaction between the crop, indigenous populations of rhizobia, and soil and environmental conditions, trials to determine the benefit from inoculation should account for these variables. The ultimate goal of continuing programs that involve inoculation trials should be to further quantify the complex interactions of variables determining the response to legume inoculation.