Pasture renovation with a plow will destroy
root structure, reduce support for hooves, kill valuable earth worms, burn super valuable soil
carbon, waste time and fuel and money, and is plain silly in all but extreme cases. A good mix of clovers appropriate for your area over seeded will work fine. You need to get your legumes to about 35-40% of forage mass. You can do this easily by using modern electric
fence, making small breaks, and keeping forage fairly short and frost seeding, as well as overseeding before grazing each paddock. You must remember most clovers have from just under a million seeds per pound, to over a million depending on variety. A four or five variety clover mix broadcast at 2 or 3 pounds an acre at frost seeding, and another 1/8-1/4 pound one or two times a growing season will lay down an adequate seed bank in addition to what you have present. If you do intensive, small breaks and keep the
canopy short for a restoration period grazing down to 4" of compressed height with a home made falling plate meter, and getting back on it before it is 9" tall, you can suppress your warm season grasses and significantly shift production to legumes. Improved varieties of medium red and medium white clovers can support some very impressive
milk production. Keep a watchful eye on your root mass of tall grasses, as not too kill them, simply do this two or three times to stun them and let some other stuff get going, then let them grow up to fuller heights to recover. You can also use tall clovers like a low-coumarin tall sweet clover, Illinois bundle flower, or other tall legume to mix with a tall bunch grass for protein with a taller sward height.
It gets a lot more specific, depending on your management capabilities, temperature, soil and rainfall. Your cow's dry matter intakes, the moisture and maturity of the pasture, and access and distance to quality
water will mean a great deal as well.
If you meant switch grass, which is a warm season grass, throwing out some cool season stuff like some of the high yielding, high quality Kentucky blue grasses from Barenbrug,
http://www.barusa.com/forage/products/kentucky-bluegrass and an annual ryegrass for cool season production won't hurt anything. Again broad cast into standing sward immediately before a graze, let the cows tamp it in and ferti-gate with their natural byproducts!
Annual brassicas can give you great extension of grazing season and really improve soil tilth and water infiltration, as well as tying up nutrients so they don't run away during winter or early spring rains. I toss out a pound of each of daikon radish, purple top turnip, grazing kale, and swedes(rutabagas) in mid July into standing paddocks right before I graze. Often these are cool season grass paddocks that are going senescent and dormant, and I graze it down tight to allow the brassicas to take off and get some growth before fall flush fires the blue grass, orchard grass and fescues back up. Then stay off of these until mid to late fall and then strip graze and utilize well into winter!
You
should subscribe to Allan Nation's Stockman Grass Farmer or Joel McNair's Graze
Magazine and get some low cost education. They both have example articles on their websites.
https://www.stockmangrassfarmer.com/articles/index.php?start=25
http://www.grazeonline.com/category/dairy
Best of luck and Happy New Year!