How to use zinc sulphate heptahydrate in agriculture?
I would like to know how to use zinc sulphate.
I bought zinc sulphate heptahydrate and will spray it on my pecans.
I read values for zinc sulphate (36%).
I think that 36% means 36% of zinc, isn't it?
So this kind of zinc sulphate should be the zinc sulphate monohydrate.
The heptahydrate that I bought should have a 20% of zinc, so to have the same quantity I should use a little bit more.
To find how much of heptahydrate I should use I did this procedure : (monohydrate quantity *36):20= heptahydrate quantity.
Is it correct?
Yes your calculation is correct.
Zinc Sulphate Monohydrate (ZnSo4.H2O) contains 35 - 36 % elemental zinc and zinc sulphate heptahydrate (ZnSo4.7H2O) contains 21.5 to 22% elemental zinc.
So the recommended Zinc Sulphate Monohydrate (ZnSo4.H2O) for pecan tree is 1 pound per tree for first three years after planting.
If using zinc sulphate heptahydrate ( 20% zinc element), you need
Recommended: 1 pound (454 g) zinc sulphate monohydrate (@ 36 %) per 25 Sq. foot area around the tree (40 pound zinc sulphate monohydrate per 1000 Sq. feet)
So need 72 pounds of zinc sulphate heptahydrate per 1000 Sq. feet
1.8 pounds (817g) of zinc sulphate heptahydrate per 25 Sq. foot area around the tree.
(Quantity of zinc sulphate Monohydrate) X (36% )÷ (% of element zinc in zinc sulphate heptahydrate)