A word about legumes and nitrogen fixing:
"Legume" refers to plants that have the ability to convert atmospheric nitrogen ,which is normally unavailable to the plant, to a form of nitrogen that the legume can use for growth. Rhizobia in the soil "infect" the roots which causes nodules to form on the roots. These nodules are the site of the conversion of nitrogen to a form which is usable by the plant. Inoculating the seed places the correct rhizobia in contact with the seed which assures more nodules are produced which results in adequate nitrogen fixation for maximum production potential. Contrary to some beliefs, legumes DO NOT pump nitrogen into the soil for other plants to use. The nitrogen that is fixed in the soil following a legume crop is a result of the biodegradation of the roots, nodules, and other plant material from the legume plant. Legumes can fix great amounts of nitrogen into the soil when plowed in as a "green manure" but they do not transfer nitrogen to non legume plants growing in the same field at the same time.