Make the hay late in fall so there is very little residue in spring then either frost seed or drill it in spring as early as possible. If you catch timely rains in spring you can get a good mix. A friend did this with some CRP fields that were all grass 2 fields turned out good 1 field lacks fertility and didn't do as well. Other thing would be if there is a lot of grass over winter. Burn it off with fire.