The following information is adapted from a PowerPoint presentation created by Tim Wagar, Former Regional Minnesota Extension Educator
Definition of Ag Liming Material
- Contains Ca and Mg compounds that can neutralize soil acidity
- Limestone
- Quicklime
- Hydrated lime
- Marl
- Shells
- Byproducts
Agricultural Limestone
- Mixture of Calcite (CaCO3) and Dolomite (CaCO3 + MgCO3)
- Calcite: 40% Ca and 0-0.6% Mg
- Dolomite: 21.7% Ca and 13.1% Mg
- Ca:Mg ratio of crops is closer to that of dolomite
Agricultural Limestone Quality
- Laboratory measurement of chemical effectiveness: % Total Neutralizing Power (% TNP)
- Particle size from crushing/grinding (Fineness Index)
- (Fineness Index) X (% TNP) = % Effective Neutralizing Power
- (% ENP) X (2000 lbs) X (% Dry matter) = Pounds of Effective Neutralizing Power/ton
Liming Materials - Winona County, 1991
| Lime | ENP Application (lb/acre) | pH | Exch Ca (ppm) | Exch Mg (ppm) | Ca/Mg Ratio* |
|---|---|---|---|---|---|
| Check | - | 6.3 | 2412 | 292 | 8.26 |
| Dolomite | 3594 | 6.4 | 2463 | 343 | 7.18 |
| Calcite | 2988 | 6.7 | 2791 | 310 | 9.00 |
| Dolomite + 400 lb | 3594 | 6.6 | 2414 | 419 | 5.77 |
*4.33 is the "Ideal Ratio"
Liming Materials Yield - Winona County, 1991
| Lime | ENP Applied (lb/acre) | Yield* (Ton D.M./acre) |
|---|---|---|
| Check | - | 2.6 |
| Dolomite | 3594 | 2.6 |
| Calcite | 2988 | 2.5 |
| Dolomite + 400 lb | 3594 | 2.6 |
*2 cuttings
Ag Lime Effects on Alfalfa, Rochester Center Plots - 2000
| Lime Source |
Mg Application (lb/acre) |
ENP Applied 0 lb/acre (ton D.M./acre) |
ENP Applied 1750 lb/acre (ton D.M./acre) |
ENP Applied 3500 lb/acre (ton D.M./acre) |
ENP Applied 5250 lb/acre (ton D.M./acre) |
| Calcite | 0 | 1.82 | 2.37 | 2.24 | 2.29 |
| Calcite | 300 | 2.09 | |||
| Dolom | 0 | 2.36 | 2.30 | 2.46 | |
| Dolom | 300 | 2.30 |
Ca:Mg Ratio - 4.1
Ag Lime Effects on Alfalfa - 2001
| Lime Source |
Mg Application (lb/acre) |
ENP Applied 0 lb/acre (ton D.M./acre) |
ENP Applied 1750 lb/acre (ton D.M./acre) |
ENP Applied 3500 lb/acre (ton D.M./acre) |
ENP Applied 5250 lb/acre (ton D.M./acre) |
| Calcite | 0 | 3.23 | 3.63 | 3.62 | 3.53 |
| Calcite | 300 | 3.61 | |||
| Dolom | 0 | 3.73 | 3.62 | 3.51 | |
| Dolom | 300 | 3.72 |
Ag Lime Effects on Alfalfa - 2002
| Lime Source |
Mg Application (lb/acre) |
ENP Applied 0 lb/acre (ton D.M./acre) |
ENP Applied 1750 lb/acre (ton D.M./acre) |
ENP Applied 3500 lb/acre (ton D.M./acre) |
ENP Applied 5250 lb/acre (ton D.M./acre) |
|---|---|---|---|---|---|
| Calcitic | 0 | 3.92 | 4.08 | 4.19 | 4.26 |
| Calcitic | 300 | 4.04 | |||
| Dolom | 0 | 4.08 | 4.04 | 4.2 | |
| Dolom | 300 | 4.11 |
Summary
- No agronomic evidence that Mg levels in dolomite lime are detrimental to alfalfa
- Should be more concerned about introducing grass tetany in cattle from forages grown on soil with the exclusive use of calcitic lime
- No agronomic or economic reason to "import" purported calcitic lime
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