In a large saucepan, (5 or 6 litre size) combine sugar, baking soda, salt, buttermilk and corn syrup. Bring to a boil, stirring constantly. Reduce heat to medium-low, continue cooking until mixture becomes caramel-colored and reaches soft ball stage (238 degrees). Remove from heat, add butter and pecan halves. Beat until thick enough to drop from a spoon onto waxed paper. If mixture becomes too hard, return to heat and add small amount of water. Stir until smooth. Yield: 44 to 48 Pralines. Variation Reduce sugar to 2 cups. Omit corn syrup. Increase butter to 0.75 cup, add 1 teaspoon vanilla. Include butter in cooking stage. Add vanilla with pecans.