Earth Science Fast Acting Iron adds essential minerals back into the soil for a deeper green without excessive lawn growth. Non-staining and non-burning formula. Safe to use any season on any type of grass. Contains Earth Science's patented Nutri-Bond Technology, which naturally bonds with soil to help reduce nutrient run-off and waste. It is the result of years of research into methods of reducing fertilizer run-off and waste. Nutri-Bond naturally bonds with the soil to help keep more product where you put it.