It's harvesting a tiny seed! You need either extremely expensive equipment, or an old Allis Chalmers "all crop" combine, screens are available, and with new canvas, which can be had from the Amish merchants, you should be fine. That's what I use. You might be advised, that planting is just as specialized, I use an old JD alfalfa drill, with grass boxes on the back. Any tractor will be of sufficient weight will handle it. I have used an Farmall M, used an 8N, a couple of times, now a Massey 35 Perkins diesel. If you have a hilly terrain, bigger will help you, as well as LPTO. If you have a small project, just use a hand sickle bar, a bag, hang till dry, a hoe to tear the ground, and to provide ground contact. Basically to drill. Try to recruit young people to hoe and backfill, for a conservation project, boy scouts, girl scouts, even some pheasants forever chapters might help. The state conservation agency rents drills in Missouri for example.