Roots Turf Food 7-7-7 contains 4% iron to promote green growth. Controlled-release formula combines organic-based fertilizer, biostimulant compounds, and Novozymes microbes to increase plant performance and stimulate root growth. Microbes produce enzymes that release nutrients in soil and chelates that enhance nutrient uptake. Comes in 50-lb. bags. Novozymes Biologicals, Inc., Salem, VA