Humboldt Nutrients Master A&B is a premium two-part fertilizer program designed for all plants and made with the highest quality mineral ingredients. What sets the Master Series apart from it’s peers is the amino chelation of heavy metal micronutrient content. Other synthetic 2-part and 3-part programs use cheaper imported Chinese chemical chelating agents called EDTA and EHDDA, to make micronutrients available. These are highly toxic chemicals and are not good for our soils, waterways, or human health. By using natural amino acids to make all of the micronutrient content available in the Master A&B, we have made it 100% biodegradable, which is more sustainable environmentally, without sacrificing efficacy or affordability.