Types of Liming Materials
Limestone rock is formed from the compressed skeletons of dead marine creatures. Limestone rock is a rich source of calcium and soils formed from such rocks contain plenty of lime. In Ireland, our main source of lime is from limestone quarries. Here, the rock is ground to a fine material suitable for spreading on the land
- Ca CO3 Ground Limestone (Calcium + Carbonate)
- Ca O Burnt Lime or Quicklime (Calcium + Oxygen)
- Ca(OH)2 Slaked lime (Calcium + Oxygen + Hydrogen)
- Dolomite (magnesium limestone) - calcium magnesium carbonate (CaMg(CO3)2 - A mixture of CaCO3 and Mg CO3
Calcium limestone is the most common form of ground limestone available. Magnesium limestone (also called dolomitic limestone) can also be used, and are recommended where soil test magnesium levels are less than 50 mg/L.
Ground limestone can range from dust up to particles of 3.35 mm in diameter. Limestone needs to dissolve in the soil before it can be fully utilised and this process can take up to two years. Smaller limestone particles are available much more rapidly and will react with the soil and raise pH much faster than coarse materials.
Lime Standards as per DAFM Specification (SI 248)
- Product must have a Total Neutralising Value of not less than 90 per cent
- All the product must pass through a 3.35 mm sieve.
- Not less than 35% must pass through a 0.15 mm sieve
- The moisture content must be less than 3.0%
Lime which is ground much more finely (< 0.1mm) than ground limestone and then formed into granules is known as granulated lime.
Granulated lime is spread at a rate of 3:1, Ground Limestone to Granulated Limestone. For example, If you require 3 tonnes/acre of ground limestone, therefore this is equivalent to 1 tonne of granulated lime spread over 5 years. In this example, the annual application of granulated lime is 200kg/ha per year. (1,000/5 =200kg/ha/yr)
|Useful on conacre, immediate short term response|
|Useful on lime deficient soil before sowing tillage crops||More expensive than Ground lime|
|Spreadable with fertiliser spreader||Large application required on low pH soils|
|Granules do not blow away|
|Best suited where pH is good, only maintenance dressing required|