I just bought my pullets a container to use as a dust bath. I have DE but that's about it. We don't have a fire place to get ash from and living in Washington makes for wet mud not dirt. I was going to buy some potting soil but I wasn't sure about the fertilizers in it. I don't want to poison my girls. I was wondering if I could use Pete Moss or should I just go to the river and get some and and dry it out?