Among those coating materials, insoluble inorganic materials such as sulfur used to be attractive candidates, since they could not only retard the release of nutrients from fertilizers but also have additional functionalities such as secondary plant nutrients and agents that neutralize soil alkalinity. After this, polymers were widely used as coating materials, as sulfur film formed on the surface of fertilizer granules are frail, accompanied by some cracks and pores , and it is also vulnerable to microorganisms