New Seeding of Alfalfa into field that has been in 8 years

Got a field of that has produced very nicely in alfalfa grass mix hay for past 8 years. This year yield dropped off. So time to plant new. What are thoughts on planting new crop in spring? Fertilize per soil test, plow it under. Oats as cover like would be any new field. Would it work in regards to autotoxicity? Still has some alfalfa in it. These fields cannot go to corn.

New Seeding of Alfalfa into field that has been in 8 years