Yummy Rhubarb Bread

1 1/2 cups brown sugar
2/3 cup salad oil
1 egg
1 cup buttermilk
2 1/2 cups flour
1 tsp. soda
1 cup rhubarb, diced
1/2 cup walnuts
Mix all ingredients together in order given & divide between two loaf pans. Blend 1/4 cup brown sugar & 1/2 tbsp. butter. Sprinkle over top of batter. Bake at 350 degrees for 35-40 mins.