Is bentonite good for earthing?
‪Bentonite | Earthing Compounds | Granular Bentonite | Powder ...‬‏
Advantages Of Bentonite Earthing Compounds

Bentonite is used to lower the resistance to earth by providing ground enhancement effectively reducing the resistance between the soil and earth electrode (such as copper earth rod or earth mats) by retaining moisture.

How to mix bentonite for earthing?
The recommended ratio is typically 5–10% bentonite powder by weight. Stir until you get a thick, homogenous slurry. Pour the Slurry: Slowly pour the bentonite slurry into the trench or borehole, surrounding the earthing rod or electrode.