In a large pot over medium heat, combine chicken broth, water, green onions and brown rice,carrots and mushrooms. Bring to a boil, then reduce heat and simmer until rice is tender, 35 to 40 minutes.
When rice is tender,
Melt the margarine in a medium saucepan over medium-low heat. Stir in flour, poultry seasoning and pepper all at once. Cook, stirring, until smooth and bubbly. Stir in half-and-half and cook until thickened, 2 minutes. Stir half-and-half mixture into rice mixture. Stir turkey and sherry. Heat through and serve.