On many of the soils not currently used for growing agricultural crops, there is tremendous merit to managing your food plots with a no-till "throw-n-mow" type of approach. This means soils heavy in sand, clay, rocks, etc. are best managed by rarely, if ever, breaking the crust of the soil to plant. If you feel you must do this, keep the tillage to an absolute minimum. Experience has taught many of us that the timely application of spraying gly, broadcasting specific seed types, and mowing to keep OM on/near the surface of lousy soils makes for less work, less expense, and good/better results.
Buckwheat in the summer, winter rye and alsike clover in the fall. You also have to decide if you are improving habitat or creating a "kill plot". Neither approach is wrong, but you need to factor in what is happening on the land surrounding yours to determine how your interests are best served, or if you're willing to set aside your interests (to a certain extent) to benefit the land and wildlife, as a whole.