Soil should never be used as a tortoise substrate. You can't know what type of composted yard waste it is made from and it could be something toxic. All the additives are just an additional problem. The makers/sellers do not intend for live animals to be kept on their product in little indoor enclosures.Hi im looking to use topsoil along with orchid bark but i cant find anywhere near me that sells sterilised top soil. can i just use normal top soil? Thanks