I have 6 chickens in a small coop/tractor which is built on top of a standard lawn tractor dump cart, with the litter being down in the cart portion. It has an enclosed run attached. I have seen a lot of pictures of deep litter coop floors and all have a thick layer underneath the top layer of shavings. The litter has been in for a few months and I mix it up weekly but it always stays dry and loose instead of packed. However, even though the litter (pine shavings) is dry, there keeps being a smell of ammonia. I am now 6-7 inches deep on the litter and running out of room to add more. I'm sure there is something I am missing. Should I remove all but an inch or two and start again? I'm in New England and winter is coming, wanted to do deep litter so the biomass will provide some heat.