I know they have experimented with various blends of "dirt glue" and additives over the years, I was talking to Chris about it recently but forgot the name of the product he was using, if he's around the track tonight, I will ask him again. Not sure how often he checks the message board but will tell him you sent one for him to check as well.
If I had to guess, something like this product here might work, though I am not sure if there is a more economical way of buying something like this in bulk that the Allison's may be using:
https://www.amazon.com/Mulch-Lock-16...80249878&psc=1