There are lots of crops to plant instead of corn for a food plot. Wheat, rye, oats, beets, radishes, kale, rape, clover(red, crimson and ladino) and others. I just planted grain rye, kale, radishes and beets in my small food plot. All I need now is rain. Clover is a legume and will fix nitrogen in the soil from the atmosphere. There are food plot blends you can get from big box stores. Ask your local DNR about suggestions and again contact Eric Krewson. He lives near Birmingham I think and is very knowledgeable about deer hunting, food plots, etc and is very generous with his info.
I just rough up the ground and use a hand spreader to disperse the seeds then drag something over it to cover the seed. I use an old cyclone fence gate to drag behind my riding mower.
Another thing to add is salt licks. One or two locations on your 40ac. Buy a 50# livestock salt/mineral block from feed store or Tractor Supply and place it on the ground in an area where deer will feel safe. It will eventually melt into the ground but the deer will dig and eat the salty dirt. I usually put 2 out a year, in early spring when they use it most and mid summer. They and other critters will use the salt all year long.