Thanks Keith,  I Guess in good growing conditions it might not make any difference, but what about under drought stress?  Are the nodules just as effective when the soil is dry?

BTW,  My Mn test strip is barely visible anymore. I haven't seen it in a while ,but the last time I saw it, the upper leaves were not showing any Mn def. symptoms. I guess they outgrow the hunger when the roots penetrate the soil to greater depths. I have noticed this in my neighbors fields at more than one occasion. Not sure about the yield difference tho. I feel better when I spray my beans and they turn green when the neighbors stay yellow. There has to be some yield drag there.