A common source of silicon is clay. Clay particles contained in the soil largely determine a soils suitability for cultivation. The most frequently found silicate clays are aluminum silicate, magnesium silicate, calcium silicate and potassium silicate. Silicates are a decisive factor in the healthy development of plants, not only for the silicic acid content, but also for trace elements, pH buffering, and enhancement of the microbial population in the growing medium.

Clay surfaces absorb large amounts of plant nutrients without any appreciable change in the osmotic concentration of the growing medium or fluctuation of pH. The bond which holds clay together is very weak. The potential bonding with water is stronger than the bond with the clay, resulting in the clay literally falling apart when exposed to water. This falling apart creates a slow release of silicic acid, which is the property of PyroClay.