Can magnesium nitrate directly replace magnesium sulfate at equal total magnesium?

The replacement adds nitrate nitrogen and removes an existing sulfur source. Hygroscopicity may also make a bag-weight concentration estimate unreliable.

Account for nitrogen and sulfur as well as magnesium

Align the elemental Mg or MgO basis. Include the additional nitrate nitrogen and missing sulfur. Compare opened material with the retain for concentration, clarity and residue under the same mixing-water conditions.

Why can stock concentration be low after hot, humid storage?

Check moisture uptake through the packaging and the weighing basis. Compare batch moisture and elemental results. Magnesium and nitrogen formulations: Calculate nitrate nitrogen and magnesium separately. Check EC and clarity at the target stock concentration. Replacing magnesium sulfate: Trial at equal magnesium. Adjust nitrate nitrogen and sulfur and verify the nutrient balance of the full formulation.

Checking Water-soluble magnesium (as MgO) and Nitrate nitrogen

Water-soluble magnesium (as MgO) (% by mass): This example reports water-soluble MgO. Convert to the same basis before comparing with elemental Mg. Nitrate nitrogen (% by mass): Give separate values for total, nitrate, ammonium or amide nitrogen as applicable. Use a common as-received basis. Water-insoluble matter (% by mass): Agree water temperature, sample-to-water ratio, filter medium and the drying and weighing procedure. Test compatibility separately with site water.

What to record

  • Magnesium basis
  • Nitrate nitrogen
  • Sulfur difference
  • Condition after opening
  • Stock concentration

Technical references

Products and processes

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