Natural liming
The principal UK deposits of Calcium Carbonate (CaCo3) Natural Agricultural Lime products are:
Limestone CaCo3 – a sedimentary rock, which is more compacted and denser than Chalk, it is formed from the remains of microscopic foraminifera. Typical Limestone Neutralising Values, dependant on the geological strata, vary between 50 - 55N.V.
Magnesium Limestone CaMg(Co3)2 – formed in the same way as Limestone, but the sedimentation process occurs in the presence of magnesium resulting in a dolomitisation process. Thus Magnesium Limestone typically contains both Calcium (CaCo3 - 42%) and Magnesium (MgCo3 - 53%) carbonates. Typical Neutralising Values are 56%NV.
Chalk CaCo3 - a less densely compacted and geologically younger sedimentary rock predominantly composed of compacted coccoliths (Sea Algae). As a 'softer' rock chalk is more readily broken down and absorbed into the soil solution. Typical Neutralising Values vary between 48 – 54% NV.
Full specifications of all three products in either their natural or Calcined (Burnt) are listed in the 1991 Fertiliser Regulations .
All ALA Members supply Agricultural Lime products in accordance with the current Fertiliser Regulations and the 'Statutory Statement' is provided to the initial purchaser. Quarry produced materials can be sold under a number of permitted names (the term 'Agricultural Lime' is insufficient), each name has a precise meaning and associated declarations, which are required by law.
Farmers should ensure such information is available to them at the time of delivery (as required by law) and that the lime quality is clearly identified at the time of quotation.
pH optimises fertiliser effectiveness
All ALA members supply agricultural lime in accordance with the current Fertiliser Regulations and the 'Statutory Statement' is provided to the initial purchaser.
The UK has a good spread of deposits of natural chalk and limestone suitable for this purpose, though Scotland is short of limestone and relies on imports to a large extent from the North of England.
The Fertiliser Regulations control the sale of agricultural liming materials. Quarry-produced materials can be sold under a number of permitted names (the term 'Agricultural Lime' alone is insufficient), each name has a precise meaning and associated declarations, which are required by law.
Farmers should ensure that such information is available to them at the time of delivery (as required by law) and that the lime quality is clearly identified at the time of quotation.
Materials produced for agricultural liming must comply with the Fertiliser Regulations. Many production sites will hold accreditations for Environmental Management Systems.
The fertiliser regulations and lime
Name, meaning and required declarations of some quarry produced liming materials to comply with the current fertiliser regulations.
| Name ofMaterial |
Meaning |
Declarations
See Note below |
| Ground limestone |
Sedimentary rock consisting largely of calcium carbonate and not more than 15% of magnesium expressed as MgO and of which 100% will pass through a sieve of 5 mm, not less than 95% will pass through a sieve of 3.35mm and not less than 40% will pass through a 150 micron sieve |
Neutralising value
Any amount of material as a percentage by weight that will pass
through a 150 micron sieve |
| Screened
limestone |
Sedimentary
rock consisting largely of calcium carbonate and not more than 15%
of magnesium expressed as MgO and of which 100% will pass through
a sieve of 5 mm, not less than 95% will pass through a sieve of 3.35
mm and not less than 20% will pass through a 150 micron sieve |
Neutralising
value
Any amount of material as a percentage by weight that will pass
through a 150 micron sieve |
| Limestone
dust |
| Coarse
screened limestone |
Sedimentary
rock consisting largely of calcium carbonate and not more than 15%
of magnesium expressed as MgO and of which 100% will pass through
a sieve of 5 mm, not less than 90% will pass through a sieve of 3.35
mm and not less than 15% will pass through a 150 micron sieve |
Neutralising
value
Amount of material as a percentage by weight that will pass through
a 150 micron sieve |
| Coarse
limestone dust |
| Magnesian
ground limestone |
Sedimentary
rock consisting largely of calcium and magnesium carbonates and not
less than 15% of magnesium expressed as MgO and of which 100% will
pass through a sieve of 5 mm, not less than 95% will pass through
a sieve of 3.35 mm and not less than 40% will pass through a 150 micron
sieve |
Neutralising
value
Amount of material as a percentage by weight that will pass through
a 150 micron sieve |
| Magnesian
screened limestone |
Sedimentary
rock consisting largely of calcium and magnesium carbonates and not
less than 15% of magnesium expressed as MgO and of which 100% will
pass through a sieve of 5 mm, not less than 95% will pass through
a sieve of 3.35 mm and not less than 20% will pass through a 150 micron
sieve |
Neutralising
value
Amount of material as a percentage by weight that will pass through
a 150 micron sieve. |
| Course
magnesian screened limestone |
Sedimentary
rock consisting largely of calcium and magnesium carbonates and not
less than 15% of magnesium expressed as MgO and of which 100% will
pass through a sieve of 5 mm, not less than 90% will pass through
a sieve of 3.35 mm and not less than 15% |
Neutralising
value
Amount of material as a percentage by weight that will pass through
a 150 micron sieve. |
| Course
magnesian screened limestone dust |
| Chalk |
Cretaceous
limestone |
Neutralising
value |
| Ground
chalk |
Cretaceous
limestone of which 98% will pass through a sieve of 6.3 mm |
Neutralising
value |
| Screened
chalk |
Cretaceous
limestone of which 98% will pass through a sieve of 45 mm |
Neutralising
value |
| Ground
burnt lime |
Commercial
calcium oxide containing not more than 27% magnesium as MgO and of
which 100% will pass through a sieve of 6.3 mm |
Neutralising
value |
| Kibbled
burnt lime |
Commercial
calcium oxide containing not more than 27% magnesium as MgO and of
which 100% will pass through a sieve of 45 mm |
Neutralising
value |
| Burnt
lime |
Commercial
calcium oxide containing not more than 27% magnesium as MgO |
Neutralising
value |
| Magnesian
ground burnt lime |
Commercial
oxide obtained from magnesian limestone containing more than 27% magnesium
as MgO and of which 100% will pass through a sieve of 6.3mm |
Neutralising
value |
| Magnesian
kibbled burnt lime |
Commercial
oxide obtained from magnesian limestone containing more than 27% magnesium
as MgO and of which 100% will pass through a sieve of 45mm |
Neutralising
value |
| Magnesian
burnt lime |
Commercial
oxide obtained from magnesian limestone containing more than 27% magnesium
as MgO |
Neutralising
value |
| Hydrated
lime |
Product
obtained obtained by slaking burnt lime or magnesian burnt lime of
which not less than 95% will pass through a 150 micron sieve |
Neutralising
value |
| Mixed
lime |
A product
resulting from mixing two or more forms of liming material specified
in this schedule not being materials for which there is no minimum
standard laid down in column 3 of this schedule, or material produced
during the manufacture of commercial burnt lime or hydrated lime. |
Neutralising
value
Amount of material as a percentage by weight that will pass through
a 150 micron sieve |
Note: The limits of variation
(absolute value in percentage by weight) shall be 5% of the amount stated
for all Declarations. |
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