Clay
Clay is available in various types. The type of clay required depends on the application. All clay types are capable of buffering nutrients to some degree, ensuring that they remain available during the growing season rather than being run off. In fine, powdery clay types, addition to the potting soil mixture also positively affects water absorption and moisture distribution. Additionally, the fine clay can make the pots more stable due to its high bulk density, making them less susceptible to falling or blowing over.