Mag Carbonate (Slow Release Magnesium)


  • N:0
  • P:0
  • K:0
  • S:0
  • Ca:0
  • Mg:27.5%
Hastings Store – Product in stock as well as shipping to order.
All Other Stores – Currently shipping to order.


27.5% Mg
Supplied ex Hastings Warehouse or through direct shipment to any NZ port
Supplied in bulk or bulk bags
Use in: Year round
Click here for freight rates to your farm

Products FAQs

Why Use Mag Carbonate:

Magnesium is an essential nutrient for both plant and animal production and health. Magnesium Carbonate contains Magnesium in a non-water soluble (slow release) form and will help meet long term Magnesium requirements.

  • Magnesium is found at the centre of the chlorophyll in plants and is essential to keep plants green and is actively involved in plant photosynthesis. This photosynthesis converts light to energy and is essential for the health and growth of the plant. The less magnesium a plant has the more nitrogen will be needed to grow the plant.
  • Lower Magnesium levels in soil and pasture lead to Magnesium deficiencies in livestock which are generally seen as Metabolic issues. Magnesium applications to the soil will result in healthier more productive livestock and a reduced requirement for expensive Magnesium supplements.

Precautions when applying Mag Carbonate:

  • Avoid application before large amounts of rainfall (40ml plus within 10 hours) to reduce any leaching.

When to use

Summer, Autumn, Winter, Spring

Magnesiums role in crops and pastures:

  • Crops and pastures require Magnesium to capture the sun’s energy for growth and production through photosynthesis.
  • Magnesium acts as a phosphorus carrier in plants, and is required for better root formation and thus for better nutrient and water efficiency in plants.
  • Magnesium aids in plant respiration and the activation of many enzyme systems.


  • Magnesium Carbonate is a naturally occurring magnesium fertiliser. Like lime (calcium carbonate), it breaks down over a period in the soil to provide Magnesium.
  • Magnesium Carbonate comes in a fine form (0-2mm) so is easily mixed with other fertilisers. It is not water-soluble and is therefore not prone to leaching or runoff.
  • Like lime, Magnesium Carbonate also has a significant liming effect and reduces pH equivalent to a high-grade lime.