Fertilizer is only a dangerous waste if you plan to dispose of it. Otherwise, fertilizer is a product that is regulated by the Washington State Department of Agriculture.
If your business has leftover fertilizer, you cannot throw it away or dump excess materials on the ground. You need to designate it to determine if it is dangerous waste. Fertilizer may contain dangerous materials that if disposed of improperly, can harm the environment.
If you are planning to register a fertilizer, Washington State Department of Agriculture can guide you through that process.
Find registered fertilizers in Washington.