We’ve heard many stories over the years about people using cat litter on a wet field when they run out of calcined clay products like Diamond Pro Drying Agent (being applied in the photo above). Just because it looks like calcined clay and absorbs water, doesn’t mean that cat litter is a calcined clay. Although it is true that cat litter is produced from montmorillonite clay, just like the calcined clays made for sports field applications.
The difference is in the heating of the clay. Cat litter is only fired to around 500ºF, hot enough to make the clay extremely absorbent, but not hot enough to stabilize the particles of clay. As soon as this material gets wet, its physical characteristics change and the particles melt into a slimy clay mess. It is made this way to make it easier to clean a cat litter box. The wetted areas “melt” and form a lump, after drying, that is easier to find and remove from the litter box.
Calcining clay can only be made at much higher temperatures. Processing montmorillonite clay to around 1400ºF produces clay particles that are still extremely absorbent but the physical characteristics of the particles do not change when they become wet. The stable calcined clay particles remain solid after wetting and can handle the wet/dry cycle without breaking down. On your ballfield, you don’t want that wet, slimy, and slippery clay on the surface; you want nice granulated topdressing that maintains its physical hardness after wetting.
Use a quality sports field calcined clay and be sure you have enough to get through even an unusually wet season.