1. Arrange sweet potato, turnip, carrots and parsnips in a slow cooker. Rub brisket with salt, pepper, onion powder and garlic powder. Place brisket on top of vegetables. Pour broth into cooker. Cover and cook on low until beef is tender, 6 to 8 hours.
2. Remove brisket to a cutting board and let stand 10 minutes. Skim fat from pan juices. Slice brisket. Place meat on a plate with vegetables, spoon pan juices over, sprinkle with parsley and serve.