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Tropical Fruit Discussion / Re: Calcium carbonate use for tropicals
« on: August 02, 2022, 05:54:18 PM »
I am also interested in gypsum, what tipe of gypsum is generally used? Does the builders gypsum, the one that combined with water hardens up, can be used for amending?
Gypsum is Calcium Sulphate, It can be used to supply Ca and S. It is useful as a non lime form of Ca. i.e. not Limestone or Dolomite Lime.
Gypsum will not push up the pH like lime because the Sulphur balances the Ca. In pot mixes up to about 1 kg of Gypsum per cubic metre will not alter pH.
The finer the gypsum particles the greater the reaction. Coarse Gypsum particles act as slow release. Fine powder will be used faster.
You can even bust up Gypsum based building plasterboard for a source.
Natural Gypsum is mined from deposits.
Phosphogypsum is a byproduct of Superphosphate, which is derived from phosphate rock. It can contain heavy metals etc.
When I first started investigating pot mix fertilisers, I often over did amendments. That includes an episode of top dressing Citrus rootstock pots with a good handful of coarse, "slow release" Gypsum. Over time it severely set them back. The rate was too much, and burnt the roots.
Now I would calculate the amount to apply based on the size of the pots.
Gypsum is Calcium Sulphate, It can be used to supply Ca and S. It is useful as a non lime form of Ca. i.e. not Limestone or Dolomite Lime.
Gypsum will not push up the pH like lime because the Sulphur balances the Ca. In pot mixes up to about 1 kg of Gypsum per cubic metre will not alter pH.
The finer the gypsum particles the greater the reaction. Coarse Gypsum particles act as slow release. Fine powder will be used faster.
You can even bust up Gypsum based building plasterboard for a source.
Natural Gypsum is mined from deposits.
Phosphogypsum is a byproduct of Superphosphate, which is derived from phosphate rock. It can contain heavy metals etc.
When I first started investigating pot mix fertilisers, I often over did amendments. That includes an episode of top dressing Citrus rootstock pots with a good handful of coarse, "slow release" Gypsum. Over time it severely set them back. The rate was too much, and burnt the roots.
Now I would calculate the amount to apply based on the size of the pots.