Clean the ducks well and rub the body cavities lightly with salt, pepper, garlic powder, and poultry seasoning. Stuff the cavities with pieces of onion, apple, orange and celery. Rub the ducks with the soy sauce and oil. Place in a baking pan and roast, uncovered, basting often with Burgundy wine, about every 10 minutes. Allow 10 to 15 minutes baking time per pound of duck. Remove the stuffing before serving.