Take a pick-ax to it and break it up as deeply as you can. Work in some straw (NOT hay - hay has seeds
) or woodchips, saw dust, or compost/composted manure, something organic with texture. Work it this year, turn it, add more straw or whatever, water it, let it rot. Plant beets. Beets are wonderful for conditioning soil and you can eat the tops and bottoms. Next year plant anything you want and it will grow.