"My father-in-law used to make this casserole in the oven. I switched to the slow cooker so I wouldn't need to keep an eye on it. This side dish compliments many meals. - Mrs. Garnet Pettigrew, Columbia City, Indiana"
In a large skillet, cook beef and sausage over medium heat until no longer pink; drain.
Transfer to a 5-qt. slow cooker. Add the celery, broth, water, onion, rice, mushrooms and soy sauce; mix well. Cover and cook on high for 1 hour. Reduce heat to low; cover and cook for 4 hours or until the rice is tender.