I found this in a document by the Ohio Department of Natural Resources regarding wildlife food plots:

Food plots consisting of mixtures of grains can be broadcast and then very lightly disked and/or cultipacked to cover the seed. Pure corn food plots do best if drilled in rows. Pure sorghum food plots can be broadcast or drilled; however, the broadcast method requires a higher seeding rate and a light disking to cover the seed. Don’t use herbicides or excessivecultivation on food plots. Annual weeds such as foxtail, common ragweed, lamb’s-quarters, and barnyard grass will produce additional seed and cover in the wildlife food plot.


I can add that herbicides can drastically change the vegetation structure of the application area. It may also be residual in the soil and may hamper whatever you plant. My advice would be to not use it. For one thing, when herbicides change vegetation structure and height, it may be detrimental to alot of wildlife that rely on insects for food. Since changing vegetation means insects can be reduced or not as available. This is especially hard on young ground-living birds like turkeys because young turkeys,grouse, quail etc rely on insects for food. So by changing the vegetation you risk forcing young birds to forage longer and farther which exposes them to increased predation.

Hope this helps.