Legumes are a group of plants; peas, beans, soybeans, lentils, etc. Someone suggested you grow peas which are a Legume.
Corn is a 'heavy feeder' taking nitrogen from the soil. Legumes have the ability to 'fix' nitrogen in the soil but first one must add an inoculant to help the legumes to create more nitrogen. This link explains it pretty well.
http://www.gardeningknowhow.co...
Dave wrote and article, part of which (about 1/3 of the way down the page) explains why we should consider planting the Legumes
with corn, something you may consider. There is a photo of the nodules on the roots.
http://garden.org/ideas/view/d...
Hope this helps.