Sustane's 16-4-8 was developed as a combination fertilizer to provide nursery stock with a time released 4-1-2 nutrient package blended with a 50% Sustane humus rich, premium organic base. Sustane 16-4-8 is perfect for production of perennials and woody ornamentals. Sustane 16-4-8 Nursery Fertilizer is derived from aerobically composted turkey litter, polymer coated urea, polymer coated MAP, and polymer coated potassium nitrate.