If I put on too much limestone, won't my pH go up extremely high causing "over liming injury" or trace element tie-up?
Short answer
The preferred limestone should have the percentage of calcium close to 8 times higher than the percentage of magnesium. Limestone with high levels of calcium and low levels of magnesium will not raise the pH of soil to levels where nutrients are unavailable. To determine the exact needs of their particular operation, a producer must set up comparison plots.
High calcium, low magnesium limestone requiredWhen discussing limestone, it is important to define the chemical composition of that limestone. For implementing the Growers Program, the percentage of calcium in the limestone must be to be close to 8 times higher than the percentage of magnesium.
Calcium and pH
When applied to soil, this limestone will change the pH of the soil much less than a limestone that is higher in magnesium. According to the article "Rely on pH for Calcium Needs?" (Section 3), calcium does not make the pH of the soil rise to levels that would injure a growing crop.
Many people have seen the Nutrient Availability chart of Soil pH and believe all limestone will increase soil pHs to levels that create nutrient unavailability. Limestone with high levels of calcium and low levels of magnesium will not raise the pH of soil to levels where nutrients are unavailable.
Amounts of calcium
At this point, there is some confusion about the Growers Program. The casual investigator often concludes that the program needs high quantities of limestone to make it a success.
Dr. Tiedjens was only concerned for the farmer's economic success. He wanted the farmer to apply only the amount of correct limestone that would improve the farmer's financial footing.
Comparison plots
High organic matter soils and high clay soils that have strong buffering capacities often require large quantities of limestone. However, this is not always the case. Comparison plots are the best method to determine a particular field's needs.
