Probably peat? Once it dries out, it's very difficult to re-wet. That's why you find so many being against it.
Doesn't matter how much you water, water just drains out. Root ball is usually 'enclosed' in a hard blob of peat.

Very organic soil would not dry out the same (it would retain water much longer), but it is not so great to use for growing in pots.
Try to mix in generous amounts of perlite and/or grit if you can get it.

First thing I do when I get my plant home is get rid of the peat and soil from the nursery. It is not only The peat and its hydrophobis characteristics that concerns me. Many wholesale growers are not as diligent as we would like them to be. It is the bugs that are in the soil that I can only guess at that . I only want MY bugs. I have enough problems with them. I am still aloe mite, agave bug free . I will ask to get rid of the dirt at the nursery. I take home my plants bare root if they will let me.