Thermopotash ThermoPotash is a slow-release, multi-nutrient fertilizer product made from a silicate-based potash resource. It contains on average 4%-14% K2O. It is derived by performing a pyrometallurgical process on Verdete (green) slate rock and limestone. ThermoPotash is being developed as an alternative to current potash sources, such as potassium chloride (KCl) and potassium sulfate (K2SO4). References Category:Agricultural chemicals Category:Inorganic fertilizers Category:Potassium compounds