When growing up on a family farm (the good ol' days) in Lavaca County, TX, zone 8b 1 1/2 hrs south of Austin, my dad and other farmers would plant nitrogen-setting legume cover crops for the winter and then plow these under in time to plant corn, cotton and other crops. These would do wonders providing nitrogen ,organic matter and improved soil tilth as clovers can have deep roots which help loosen the soil. http://www.soilandhealth.org/01aglibrary/010139fieldcroproots/010139ch14.html
I recall Austrian Wonder peas which could be plowed under earlier for earlier crops such as corn. Sweet clover and Huban clover would be turned under later with cotton and later hay forage crops planted. A seed innoculant is usually vital to improve N2 setting.
I have had sweet corn stalks 12 foot tall with huge ears following use of Huban clover in the garden.