Beans make great food plots. They provide very high quality food, both in the foliage and the actual beans later in the year. They are prone to overgrazing and have a low nitrogen requirement, but require moderate levels of both phosphorus and potash. Soybeans are typically used on plots larger than 5 acres to minimize the chance of overgrazing. Weed control is easy in most soybeans because Roundup Ready soybeans rule these days. Soybeans offer the additional benefit of being a food source in both summer (foliage) and winter (beans). There are now new roundup ready forage soybean varieties on the market. These offer a greater resistance to overgrazing while providing more forage on less acreage. Cowpeas and lablab are drought tolerant and also tend to be more resistant to grazing and drought. I start considering a mix of cowpeas and lablab in plots larger than two or three acres depending on deer density. These beans can also tolerate lower pH than most soybeans, down to around 5.5. Actual bean production will not be as great as soybeans.
Aeschynomene and alycelover are warm season annual legumes that tolerate grazing better than any of the beans. Forage quality is still very good, but protein is less than any of the beans. They also tend to be more susceptible to drought than the beans. Aeschynomene is particularly well suited to shady or damp woodland plots receiving only a few hours of direct sunlight per day.
Kobe and Korean lespedeza are warm season legumes that tolerates drought and poor soils better than either aeschynomene or alyceclover. The forage of these small lezpedezas is lower in quality than either soybeans, cowpeas, lablab, aeschynomene, or alyceclover, but they might be the only viable option on shallow infertile soil.
Buckwheat is another choice for poor soil or drought prone areas. It can be a good soil builder, putting tons of green manure back in to soil. Buckwheat allows you to provide summer forage while improving your soil.