How often do you see rhizobium nodules the size of golf balls? I have only observed them on sun hemp.
The nitrogen fixation process of rhizobium bacteria in legume nodules has a reducing effect and shifts the soil microbial community in the direction of disease suppression. Forage legumes should be a part of our crop rotations and ecosystems for more reasons than just supplying nitrogen. Because of their reducing effect, they also increase manganese and iron availability from the soil reserves which are present in the oxidized form that plants don’t utilize.