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- Are number of different amendment materials used to neutralize soil acidity.
- Can differ widely in potential neutralization ability.
- Individual state laws govern lime quality standards.
- Quality standards are all based on two factors:
- Purity: determined by chemical analysis
- Particle size distribution: determined by mechanical analysis.
- State laws specify methods and calculations used to identify relative quality rating for use in commercial trade.
¶ Table 1. Sieve and Particle Size Conversions
|
Standard sieve
(mesh size) |
Openings per
square inch |
Nominal Sieve Opening |
| inches |
mm |
| No. 4 |
16 |
0.1870 |
4.76 |
| No. 8 |
64 |
0.0937 |
2.38 |
| No. 10 |
100 |
0.0787 |
2.00 |
| No. 20 |
400 |
0.0331 |
0.841 |
| No. 30 |
900 |
0.0234 |
0.595 |
| No. 40 |
1,600 |
0.0165 |
0.420 |
| No. 50 |
2,500 |
0.0117 |
0.297 |
| No. 60 |
3,600 |
0.0098 |
0.250 |
| No. 100 |
10,000 |
0.0059 |
0.149 |
- Identifies fraction of sample that is “pure lime”.
- Impurities may include sand, shale, dirt, other minerals.
- Purity determined by dissolving sample of material in standard acid solution.
- Carbonate and oxide fractions react with solution.
- Analysis measures change of solution pH after reaction is complete.
- Expressed as percentage of “calcium carbonate equivalent” (% CCE).
- Analysis does not actually determine calcium carbonate content of material.
- Does indicate equivalent neutralizing value of lime material.
- Actual CCE of most lime materials will be less than 100%.
- Due to impurities in the rock; e.g., sand, shale, dirt, other minerals.
- CCE differences of pure materials due to molecular weight differences.
- For pure calcium carbonate (CaCO3), CCE = 100%
- For pure magnesium carbonate (MgCO3), CCE = 108.5%
- On pound-for-pound basis, pure MgCO3 is 16% more effective in raising the pH than pure CaCO3.
- May be referred to as “screen analysis” or “sieve analysis”.
- Indicates percentages of a material falling within predetermined particle size limits.
- Combinations of sieve screens are specified by various state liming regulations and guidelines.
- Sieve analysis
- Procedure used to assess particle size distribution of granular materials.
- Allows material to pass through series of sieves with progressively smaller mesh size.
- Amount of material that is stopped by each sieve is weighed and expressed as fraction (or percentage) of entire sample.
- Distribution of particle sizes helps identify “fineness of grind”.
- Sieves used in lime quality analysis
- Typically consist of wire cloth (screen) bound in rigid frame.
- “Mesh” size refers to number of wires per linear inch of wire cloth.
- “No. 4” mesh has wire cloth with 4 wires per linear inch and 16 openings per square inch.
- “No. 100” sieve has wire cloth with 100 wires per linear inch and 10,000 openings per square inch.
- Wire diameter and wire spacing affect size of openings in sieve.
- Particles large than 1/4th inch will not pass through No. 4 mesh sieve and will remain on surface of wire cloth.
- Particles large than 1/100th inch will not pass through No. 100 mesh sieve and will remain on surface.
- Larger sieve size number means finer particles (see Table 1).
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