Index

Supme Grade

First Grade

Qualified Grade

Appearance

White or off-white granule crystal,no visible mechanical   impurity

N content (dry basis)% ≥

21.0

21.0

20.5

Water(H2O)content%≤

0.2

0.3

1.0

Free acid(H2SO4)%≤

0.03

0.05

0.20

Iron (Fe)content%≤

0.007

--

--

Arsenic (As)content%≤

0.00005

--

--

Heavy metal(pb)% ≤

0.005

--

--

Insoluble substance in water %≤

0.01

--

--

Note:   When ammonium sulfate is used in agriculture,it is not necessary to check the   content of Fe,As,heavy metal and water insolubles.