I would plant oats or rye (grain) this late August. Take a soil sample as soon as you can, and send it in to a local lab (most land grant universities have a lab that can test soil samples for about $10). Next year, you may want to plant alfalfa, clover, corn, soybeans, or something else based on your soil test results. Oats and rye can tolerate poor soil, and they will give you some time for lime to work (if you need it).