Soybean is the most widely cultivated crop legume in the world and was introduced into the United States in the mid-eighteenth century. Most legumes develop a symbiotic association with soil bacteria collectively called rhizobia, which leads to the development of root nodules that host nitrogen-fixing rhizobia. Soybean, in particular, associates with certain species of Bradyrhizobium and Sinorhizobium. These rhizobia are not native to the United States, so inoculation of soybeans was initially essential to establish the use of soybeans into our cropping systems. However, more than a hundred years later, the necessity to inoculate soybeans needs to be reevaluated.
Soil Science Extension
University of Wisconsin Madison