Dolomitic Lime Calculator
Estimate dolomitic lime from soil pH, magnesium ppm, Ca:Mg ratio, soil texture, CEC, incorporation depth, product CCE, ECCE, carbonate analysis, acreage, bags, and split limits.
Use this for planning before ordering or spreading. Final lime and magnesium rates should follow a current soil test, local buffer pH method, crop target, and product label.
Dolomitic Lime Recommendation
Calculated from pH gap, magnesium deficit, soil buffering, product ECCE, product carbonate analysis, and split limits.
| Texture / CEC class | Buffering strength | Base tons/ac per 1.0 pH | Dolomite planning note | Depth caution |
|---|---|---|---|---|
| Sand, CEC under 6 | Low | 1.2 to 1.6 | Small pH and Mg moves can happen quickly | Avoid heavy single surface rates |
| Sandy loam, CEC 6 to 10 | Low to medium | 1.6 to 2.0 | Often benefits from Mg if leached or low testing | Split turf and pasture applications |
| Loam, CEC 10 to 16 | Medium | 2.0 to 2.6 | Good fit for dolomite when Mg is below target | Six inch incorporation is the common basis |
| Silt or clay loam, CEC 16 to 24 | Medium high | 2.6 to 3.2 | Use soil test Mg and Ca:Mg before choosing source | Deep mixing raises total tons needed |
| Clay or organic, CEC over 24 | High | 3.2 to 4.0 | Large reserve acidity can need staged correction | Retest before repeating heavy rates |
| Magnesium test level | General interpretation | Dolomitic fit | Ca:Mg watch point | Crop note |
|---|---|---|---|---|
| Under 50 ppm | Very low for many crops | Strong fit if pH is also low | Ratio may be very wide | Legumes and vegetables often respond |
| 50 to 100 ppm | Low to moderate | Useful where target Mg is higher | Check added Mg against Ca status | Sandy soils commonly fall here |
| 100 to 180 ppm | Often adequate | Use only if pH and crop need support it | Avoid pushing ratio too low | Calcitic lime may fit better |
| Over 180 ppm | High Mg tendency | Use caution unless lab recommends it | Low Ca:Mg ratio may affect structure | Prefer calcitic source if pH needs lime |
| Ca:Mg near 4 to 8 | Common workable band | Source depends on deficiency | Do not chase a ratio alone | Use pH and nutrient levels together |
| Product type | Typical CCE | Typical ECCE | MgCO₃ range | Best use |
|---|---|---|---|---|
| Bulk dolomitic ag lime | 85% to 105% | 50% to 75% | 30% to 45% | Field scale pH and magnesium correction |
| Pelletized dolomitic lime | 90% to 105% | 70% to 95% | 25% to 42% | Lawns, gardens, small plots, and easy spreading |
| Fine screened dolomite | 90% to 110% | 75% to 95% | 30% to 45% | Faster reaction when evenly incorporated |
| Coarse quarry dolomite | 80% to 100% | 35% to 60% | 30% to 45% | Lower-cost bulk source where fineness is known |
| Custom lime blend | Use tag | Use tag | Use tag | Compare by ECCE and carbonate analysis |
| Calculated rate | Single-pass guidance | Split timing | Surface caution | Follow-up |
|---|---|---|---|---|
| Under 1 ton/ac | Usually one pass | Apply when field conditions allow | Low risk with ag lime | Retest in 12 to 24 months |
| 1 to 2 tons/ac | Often one incorporated pass | Split on turf or sensitive stands | Water pelletized lime on lawns | Allow reaction time before repeating |
| 2 to 4 tons/ac | Consider two passes | Space 6 to 12 months apart | Avoid smothering pasture crowns | Track pH and Mg by field zone |
| Over 4 tons/ac | Split strongly preferred | Stage correction over multiple windows | Do not shock sensitive crops | Use a lab recommendation first |
| Deep incorporation | Higher soil volume | Plan ahead of planting | Surface response may still be slow | Retest after mixing and reaction |
Before choosing dolomite: Confirm the soil test actually needs magnesium. If Mg is already high, calcitic lime can raise pH without adding more Mg.
Before ordering tons: Compare products by ECCE, not just CCE. A lower-ECCE dolomite may need more delivered tons for the same pH correction.
When you recieve a soil test that reveal low pH and low magnesium levels in the soil, you have to make a decision about which type of lime to use. Dolomitic lime can correct both problems, but you should only use dolomitic lime if your soil test show that you need to increase both pH and magnesium levels in the soil. You also have to determine how many pound of dolomitic lime you will need to purchase to address both the pH and magnesium issues.
Soil texture and cation exchange capacity values determines how your soil reacts to the dolomitic lime. Soils that is sandy and contain low amounts of cation exchange capacity will change pH quick when you add dolomitic lime to the soil. Soils that are clay loam or contain high amount of organic matter will take longer to change the pH when you add dolomitic lime.
Should You Use Dolomitic Lime and How Much to Buy
Because clay loam soils and soils high in organic matter will take longer to change pH, you will need to add more dolomitic lime to those soil type to achieve the same pH as other soil types. A calculator can help you determine the amount of lime you will need in your soil by taking into account the texture and cation exchange capacity of your soil. The depth to which you apply the lime will also impact the amount of dolomitic lime you need to buy.
The deeper you apply the lime, the more dolomitic lime you will need. Six inch is the depth most commonly used when calculating the amount of lime needed for a field, but if you plan to treat only the top two inches of soil, you will need to purchase less dolomitic lime. You must consider the magnesium supply in the soil when you calculate how much dolomitic lime you will need to buy.
This is because dolomitic lime contain both calcium carbonate and magnesium carbonate compounds. The magnesium carbonate is what makes dolomitic lime different than calcitic lime. If your soil test reveals that your soil contains an adequate amount of magnesium, you should not add more magnesium to the soil.
Adding too much dolomitic lime to your soil will skew the ratio of calcium to magnesium in your soil. If the ratio of calcium to magnesium in your soil becomes too low, your soil structure will tighten. Tightening of the soil structure make it more difficult for plants to grow roots in your field.
A tool will calculate the calcium to magnesium ratio of your soil now, and it will calculate the calcium to magnesium ratio of your soil after adding dolomitic lime. This will allow you to decide if you should use dolomitic lime or calcitic lime for your field. The quality of the dolomitic lime will play a role in the total weight of dolomitic lime you need to apply to your field.
The effective calcium carbonate equivalent (ECCE) is a measurement of the quality of the dolomitic lime. The ECCE take into account the purity of the lime and the particle size of the dolomitic lime. If the ECCE is low, you will have to apply more ton of dolomitic lime to your field.
For instance, two bags of pelletized dolomite will contain more neutralizing power than a larger load of coarse agricultural lime. The ECCE will allow you to calculate the amount of dolomitic lime you will need to apply to your field in bag or totes. Split application of dolomitic lime may be needed in some cases.
If the amount of dolomitic lime required to fix your pH and magnesium issues is too high to apply to your fields at once, splitting the application will allow the first part of dolomitic lime to become effective before applying the second part. Split applications are often used when applying to established pastures because applying too much lime at once can smother the crowns of the pasture plants. For split applications, you will apply dolomitic lime in two part so that the first application has time to react with your soil before applying the second part.
The time it takes to apply dolomitic lime to your field will play a role in your lime application. The faster you want your soil to react to the dolomitic lime, the shorter the time you will apply the lime to your field. The sensitivity of your crops to changes in pH or magnesium levels will also play a role in the time you apply dolomitic lime to your fields.
The values in the laboratory test of your soil may not accurately describe the characteristic of your fields. There are many factor that will contribute to the errors in applying lime to your fields. Errors can result from the moisture content of the soil at the time of liming, the evenness with which the field implements spread the liming material, and the difference between the amount of lime you purchased and the amount you spread on your fields.
Retesting the soil after twelve to twenty-four month will allow you to catch any errors in liming your fields. The soil test calculator will describe the characteristics of your fields. While this provides you with a great start in calculating how much dolomitic lime you will need to add to your fields, you must also observe the way your fields react to the dolomitic lime you have applied.
