OMRI-Listed Soluble Zinc & Sulfur for Soil, Foliar, and Hydroponic Use

Old Bridge Zinc Sulfate Monohydrate is a feed and fertilizer grade fine powder delivering 35.5% zinc and 17.5% sulfur in a 100% water-soluble form. OMRI listed and certified for use in organic agriculture, it's the go-to zinc source for growers correcting deficiencies across soil, foliar, and hydroponic programs.

Zinc is critical to plant growth hormone production, chlorophyll synthesis, carbohydrate metabolism, and respiration. When zinc is limiting, growth stalls — this fast-acting powder gets it back on track quickly, whether you're broadcasting across acres or dialing in a recirculating hydroponic system.

Nutrient Analysis

• Zinc (Zn): 35.5% minimum
• Sulfur (S): 17.5%
• Iron (Fe): 0.350%
• Lead (Pb): <0.00020%
• Cadmium (Cd): 0.00500%
• Manganese (Mn): 0.00500%
• Nickel (Ni): 0.00500%

Application Rates

• Foliar: 2–5 lb/acre
• Hydroponic stock solution: Add 0.6 g to 1 liter of water; use at 1–10 mL/gallon of working solution to achieve 0.2–2.0 ppm zinc
• Constant-feed systems: Target range 0.1–2.0 ppm zinc in nutrient solution
• Soil broadcast: Apply in granular or dissolved form to correct zinc-deficient soils

Key Features

• OMRI listed — certified for use in certified organic production
• 100% water soluble — fully dissolves for foliar, fertigation, and hydroponic use
• Fast-acting — immediately plant-available zinc and sulfur upon application
• Broad compatibility — suitable for soil drench, foliar spray, and recirculating hydroponic systems
• 50 lb bag — commercial quantity for growers, nurseries, and wholesale operations