This Standard specifies a method for the determination of chromium reducible sulfur (S_CR) by iodometric titration of distilled hydrogen sulfide trapped as zinc sulfide.

NOTE: This method determines inorganic sulfides (e.g. pyrite, marcasite, greigite, mackinawite) and elemental sulfur in acid sulfate soil without interferences from organic sulfur and oxidized forms of sulfur such as sulfate.