Soil should not be used as a substrate for tortoises. There is no type that is safe. It is made from composted yard waste and there is no way to know what is in that bag. The makers and sellers do not intend for animals to be living on it in enclosures.
The best substrate for a baby sulcata is fine grade orchid bark. Give this a read:
I chose the title of this care sheet very carefully. Are there other ways to raise babies? Yes. Yes there are, but those ways are not as good. What follows is the BEST way, according to 30 years of research and experimentation with hundreds of babies of many species. Babies hatch during the...