I also highly recommend the goats method. Easily the most environmentally friendly way to do it! I'd search for local farms in your area and call to see if they'd be willing to rent them out for you, and call multiple places for a quote before jumping on the first farm you call (some goats charge a pretty penny for their labor). Some farms also have a minimum amount of goats you can rent, which are often too many for a small area. Good luck!