Hi-Yield New Process Fertilizer Gives Quicker, Deeper Greening Than Ever Before. Formula 15-5-10 balance with sulfur and iron. Based on ammoniacal nitrogen, a faster acting nitrogen and urea nitrogen, a slow release nitrogen. Use caution when applying as iron in formula may stain sidewalks and driveways. Apply monthly. May be used on all types of grasses. One 20 Lb. bag covers about 5,000 sq. ft., the average size lawn.