To remedy this, place a pizza stone or baking sheet on the oven rack that is one level below the rack that the dutch oven is resting on.
A hard crust on the bottom of the loaf can be caused by a dutch oven that is too close to the heating element of the oven. To remedy this, place a pizza stone or baking sheet on the oven rack that is one level below the rack that the dutch oven is resting on. (NOT on the same rack.)