Dirt you wouldnt ask, they know better than we do which works better, after all without us they grow and reproduce without all of the husbandry problems we seem to experience with ours in captivity, such as impactions, infections, lack of appetite etc. You try a type of dirt (top soil, stuff found outdoors), not potting soil, mulch or any other organic based man made product and see if they use it, if they dont then you try another type of from a different location. Look at where they come from and what the soil is like there as well underground moisture, temps etc. Dont assume (make an @$$ out of "u" and "me"
that they dont know the difference or cannot tell the difference or appreciate the differences until youve tried keeping them on different subsrtates. Ive tried many (paper, wood, plastic, cocopeat, man made "organic" top soil, sand mixed with several, even store bought reptile dirt, I then found a mixture of "field dirt" (hundreds of lbs)- some sand (about 60lbs)- with dirt from a river bank thats been strained (hundreds of lbs) and a small percentage of cocopeat (4 cu ft)added to condition it and help hold moisture better) over more than 12 years with my mistakes in their husbandry, many resulting in a shortened life because of my mistakes. If dirt is right they can burrow in it, it holds a burrow, it holds moisture without being wet (think damp), it wont have any toxic additives, it doesnt spoil. But if you dont realize what a monitor is you may not recognize whats wrong with its substrate. I found out the hard way with the wrong substrate when my big albig became egg bound, yet again on improper substrates so many female monitors never even form eggs, why? They know whats needed better than we do, after all they are the experts we are just keepers. We learn from our animals, then try to help others before they have to make the same mistakes. Look at monitors kept on newspaper, wood chips, etc and see what they do, or actually what they dont do, then see what a happy monitor is on dirt deep enough to burrow in.
This pic is of an Albig over 6ft long back in her burrow, by the way this cage is way too small for now she has to deal with it though, the dirt is 1.5ft deep.
