Carbon-complexed with Micro Carbon Technology®, OMRI-Listed and CDFA (California Organic) Registered Fertilgold® Cu is an organic copper nutrient derived from copper sulfate (Cu 5.0%, with 7.0% organic matter). Fertilgold® Cu ensures efficient and effective uptake of copper, which is a micronutrient involved in many plant metabolic processes including photosynthesis, enzyme activity, protein metabolism, nitrogen regulation, and plant vigor. Copper deficiency affects grain, seed, and fruit formation.