Zinc Sulfate Grades and Specifications for US Agriculture and Feed Buyers

Published on: 2026-06-16 | Author: Chakradhar Chemicals | Read time: 7 min read

When a US buyer compares zinc sulfate (zinc sulphate) suppliers, the grade and specification decide value far more than the headline price. This guide explains the main grades, what each number on the spec sheet means, and which form fits agriculture and animal feed use, so you can buy the right product the first time.

Monohydrate or Heptahydrate

Zinc sulfate is sold mainly in two forms. Zinc sulfate monohydrate carries roughly 33% to 35.5% zinc and is the standard choice for soil application and dry fertilizer blends because you ship more zinc and less water per ton. Zinc sulfate heptahydrate carries about 21% to 22% zinc and dissolves very readily, which makes it useful where high water solubility is the priority.

Reading the Zinc Percentage

The zinc percentage is the guaranteed minimum zinc by weight. A 33% monohydrate grade delivers about a third of its weight as zinc. A 35.5% grade gives you more zinc per ton, which can lower your cost per unit of zinc even if the price per ton is a little higher. Always compare on cost per pound of zinc, not cost per ton of product.

The Specs That Decide Quality

  • Zinc content: guaranteed minimum, the number your agronomy team plans around.
  • Moisture: lower is better, since moisture is weight you pay for but cannot use.
  • Particle size and form: powder, granular or crystalline, matched to spreading or mixing equipment.
  • Water solubility: critical for foliar sprays and fertigation, less so for soil incorporation.
  • Purity and heavy metals: confirm contaminants are within limits for your crop, feed or state rules.

Which Grade for Which Use

  • Soil and dry blends: monohydrate 33% or 35.5% for the best zinc per ton.
  • Foliar and fertigation: heptahydrate or a fully water soluble grade for fast uptake.
  • Animal feed premix: a consistent, well characterized grade with a reliable COA for every lot.

Why Lot Consistency Matters More Than One Good Sample

Any supplier can send a good first sample. What protects your business is consistency from lot to lot. Chakradhar Chemicals has manufactured zinc sulfate since 1990 in an ISO certified plant, and we provide a Certificate of Analysis with every lot so your incoming quality checks are simple and repeatable.

Sourcing for the coming season? Send us your target grade, volume and US port of entry. We reply with a delivered price, a free sample and full documentation (COA and SDS) so your team can evaluate before you commit. Chakradhar Chemicals has manufactured zinc sulfate since 1990 with 30,000 plus MTPA capacity and an ISO certified plant.

Frequently Asked Questions

What is the difference between zinc sulfate and zinc sulphate? None. They are the same compound. Sulfate is the American spelling and sulphate is the British spelling.

Which grade has the most zinc? Among common grades, zinc sulfate monohydrate at 35.5% carries the highest zinc percentage, followed by 33% monohydrate, then heptahydrate at 21% to 22%.

Do you supply a feed grade? We supply zinc sulfate widely used in agriculture and animal feed applications. Tell us your specification and intended use and we will confirm the right grade and provide documentation before you order.