The south east of Ireland is unique in that it is one of the few areas in Ireland with a source of Magnesium based agricultural lime. Most of Ireland would only have Calcium based limestone within an economical transport distance.
Typically Calcium based limestone is made up of greater than 95% Calcium Carbonate (CaCO3). Dolomitic Limestone or Magnesium based limestone is typically 55% Calcium Carbonate and 45% Magnesium Carbonate.
Bennettsbridge Limestone’s has a High Calcium reserve of limestone, with consistent results of greater than 98% Calcium Carbonate.
How do you know whether you need calcium or magnesium lime?
Ideally get your soil tested and include magnesium in the analysis. The Teagasc S6 Soil Test includes Magnesium and is only €2 more than the Basic Teagasc soil test.
Teagasc offer the following advice in the “Teagasc Green Book”.
“Where dolomitic limestone is used as a liming material, it is important that it is not used repeatedly without monitoring the soil Mg levels. The release of such Mg can be very slow, and frequent use of dolomitic limestone can cause soil Mg to rise to very high levels where it can impede the availability and uptake of other nutrients such as K.”
See below map from the Teagasc Soil Atlas – Available Magnesium for the South East. It show that the South East is Index 4 / Sufficient or excess Magnesium.
Extract from Teagasc Soil Atlas of Ireland – Available Magnesium.
Teagasc Magnesium (Mg) Index System
|Soil Mg Index
||Soil Mg Range (Mg / l)
||0 – 25
||25 – 50
||51 – 100
||Sufficient / Excess
Calcium is Essential for Good Soil Structure
Good Soil Structure Associated with Correct Calcium Levels:
- Calcium flocculates the soil.
- Drainage improves. Topsoil allows excess water to pass through to subsoil, when the ratio between air, water, minerals and organic matter is correct in the soil.
- Longer growing seasons. Warmer soils mean growth starts earlier in spring and goes on later at the back end.
- Soils become robust and more resistant to slumping. Soils are harder to damage and recover sooner after poaching or compaction when exposed to traffic by machinery or animals in wet conditions.
- Plant roots penetrate deeper. The roots forage in the whole soil for nutrition, making the best of what’s available from nature. Costs are decreased.
- Less leaching of expensive fertilizer & nutrients into soil water occurs
- Nutritionally better balanced plants result, which are healthier for the animal consuming them. Fewer problems are experienced by farmers when balance is achieved. Profits improve.
- Biological life in the soil improves. Earthworms, insects, fungi and bacteria thrive and speed up the recycling process of animal and plant residues.