Fe sulfate (30%)

Heavy Metals (PPM)

Arsenic       <10

Cadmium     <5

Mercury        <.2

Lead         <5

Nickel         35

Source:   Data From Oregon Department of             Ag Organic Certification Database

Iron sulfate is used to provide fast-acting available Iron to your soil. The quantity required tends to be much higher than other micronutrient sulfates.

Iron sulfate is also powerful at reducing soil pH. However, the limit to the amount used applied usually doesn't reduce the pH by very much, making elemental sulfur a preferrable pH reducer.