Beans are one of the least demanding crops in the garden. Amending with 5-10-10 or a good compost should be plenty. Here are links explaining soil preparation, and fertilizers.
http://homeguides.sfgate.com/fertilizers-increase-growth-rate-bean-plants-61935.html
http://homeguides.sfgate.com/can-fertilizers-slow-down-growth-bean-plant-60529.html
For a more indepth look, here's a site for commercial growers.
http://ag.udel.edu/dstp/forms/Croprecs/bel.pdf
