Calcined magnesite is a magnesium fertiliser containing 48% magnesium [80% MgO] derived from magnesium oxide.

Because magnesium oxide is insoluble, it is calcined, that is, heated with lime at high temperatures, to release a little of the magniesium into plant-available form. It can be dusty and abrasive, and thus not suitable for farmer application. But, can be blended with other materials, particularly salt, kainit or sylvinite to form a high quality product.

Even so, at pH's above 7.6, a little magnesium becomes available to the plant from calcined magnesite. Granular Kieserite or Kainit [do not apply Kainit to potatoes] may be a better magnesium fertilisation option.

If you cannot afford to have all the magnesium as Kieserite or Kainit, then we can easily make you a custom blend containing magnesium from both CalMag, Kieserite and/or Kainit

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