Sugar beets are a good choice if you can keep weeds out. Anything that loves N is what I would use this year. Moving forward, I would make sure I had crops in there that would keep "mining" and recycling the N, P, and K as they eventually leach down into the soil profile. Rye, brassicas, and even buckwheat are all pretty good at mining nutrients and returning them back to the top of the soil profile when you incorporate them later on.
My neighbor got part of the area planted to corn with a bit of beans. I have the trail along the edge to try something. When it burns down from the roundup, I will try some bagas, turnips, radishes, or beets.