well, we have a covered run on soil and on top of the soil, there is a layer of aubiose.
Is your area covered? That will help it to stay drier obviously.
we dig garden lime and stalosan f into the soil once a month after we've raked out the dirty aubiose, then fresh aubiose goes on top of the soil.
If your run is open ot the elements then I don't know what to suggest.