I have had success with nwsg establishment by spraying 1-2 quarts glyphosate in mid to late march spray the same rate a second time a day or so before you plant. Plant between April 15 and May 15. Rent or borrow a no-till drill that is designed to plant nwsg seed unless you by debearded seed or straight switchgrass which can be planted with any drill that has a small seed box. Do not exceed the recommended planting rate. A field with 30-60% grass with the remainder being blackberries and weeds is more beneficial than a stand of pure grass. Layout your fields so you can manage with fire, leaving a 20-30 ft strip around the edge that you can plant in an annual green crop like oats, wheat, (that you can disk under) or a good clean clover strip can provide a perennial green fire line. If you are in an area where burning is not an option, plant to the woods edge and add any food strips out in the field. The transition from the woods to the food is softened with the tall grass.