Chicken grit is a type of small stones that chickens need to digest their food. It is usually made from flint or granite, which are insoluble and have a neutral pH. Chicken grit can also be used for plants, especially bonsai trees, that need fast-draining and aerated soil. Chicken grit helps improve the soil structure, drainage, and nutrient balance. However, not all chicken grit is suitable for plants. Some chicken grit contains calcium from ground oyster shells, which can alter the pH of the soil and harm some plants. Therefore, it is important to use chicken grit that is pure granite or flint and free of calcium for bonsai soil mix.