Preheat oven to 375°F. Grease a 9×13” baking pan. In a medium bowl, combine flour, Sugar In The Raw Organic White®, oil, cinnamon, and salt. Set aside 1 cup of this mixture. Add buttermilk, eggs, baking powder, and baking soda to what remains in the bowl, and stir to combine. Fold in half the rhubarb and spread evenly in prepared pan. Sprinkle remaining rhubarb and reserved crumb mixture on top of batter and bake until golden brown and a toothpick inserted in the center comes out clean, about 40-45 minutes. Cool at least 15 minutes before cutting into squares.