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. That's better for the environment and helps your lawn get the most out of every application. GOOD STUFF IN-GOOD STUFF OUT. 25 lb bag covers 5,000 sq. ft.