Calcitic lime is a common agricultural material used to manage soil conditions for optimal plant growth. This natural soil amendment, often referred to as “aglime,” is primarily applied to correct acidic soil environments. Farmers and gardeners use it to create a healthier foundation for crops and lawns. Its application is a routine practice in maintaining productive agricultural land, serving as a slow-release compound that improves the chemical balance of the soil over time. The choice to use calcitic lime is determined by specific soil needs identified through laboratory testing.
Chemical Makeup and Origin
Calcitic lime is composed mainly of calcium carbonate (CaCO3). The material is sourced from natural deposits of high-calcium limestone. To be classified as calcitic, the limestone must have a low concentration of magnesium carbonate, usually containing less than 5% magnesium.
The raw limestone rock is quarried and then processed to create the final product used in agriculture. This processing involves crushing and grinding the material into an extremely fine powder. The fineness of the grind directly influences the speed and effectiveness of the lime. Finer particles dissolve more quickly, allowing the calcium carbonate to begin its work sooner than coarser grades.
Role in Soil Acidity and Calcium Supply
The primary function of calcitic lime is to neutralize soil acidity. When dissolved in the soil solution, the carbonate component (CO3) of the lime reacts with and consumes the excess hydrogen ions (H+) that cause acidity. This chemical reaction effectively raises the soil pH toward a more neutral level, which is generally between 6.0 and 7.0 for most common crops.
Raising the soil pH reduces the solubility of elements like aluminum, which can become toxic to plant roots in highly acidic conditions (typically below pH 5.5). By minimizing aluminum toxicity, the lime promotes healthier root development, allowing plants to absorb water and nutrients more efficiently. The improved chemical environment also enhances the activity of beneficial soil microorganisms, including those responsible for nitrogen fixation in legumes.
Calcitic lime also serves as a direct source of the essential plant nutrient, calcium. While the primary goal of liming is acidity correction, the calcium supplied helps meet the nutritional requirements of the crop. Correcting soil acidity also improves the availability of other nutrients, such as phosphorus and molybdenum, which become unavailable to plants at low pH levels.
Distinguishing Calcitic from Dolomitic Lime
The choice between calcitic and dolomitic lime depends on the existing nutrient profile of the soil. Calcitic lime is characterized by its high calcium carbonate content and low percentage of magnesium carbonate. It is the preferred material when soil tests indicate that calcium levels are low, but magnesium levels are already adequate or high.
Dolomitic lime, conversely, is a mixture of both calcium carbonate and a significant amount of magnesium carbonate. This composition makes dolomitic lime the appropriate choice when a soil test reveals deficiencies in both calcium and magnesium.
Applying calcitic lime when magnesium is sufficient prevents the unnecessary buildup of magnesium in the soil, which can sometimes occur from repeated use of dolomitic lime. Soil testing is an important first step, ensuring the most cost-effective and agronomically sound material is selected. Both materials are typically applied as a finely ground powder, but their distinct chemical composition guides their specific use in soil management.