We are officially 5 days into having backyard chickens and loving it. Question, their run is 8'x16' and the floor is dirt and gravel. Although it is covered with sun shade material it is exposed to the elements. What is the best way to keep their run clean? I've heard using straw or pine shavings then just raking them up weekly or so. If I just rake up their droppings I'll be raking up gravel...thoughts?