Chemical composition and soil neutralizing action
Agricultural lime is produced by finely crushing natural calcitic limestone (calcium carbonate, CaCO3) or dolomitic limestone (calcium magnesium carbonate, CaMg(CO3)2).
When incorporated into acidic soils (pH below 5.5), carbonate ions react with hydrogen and toxic aluminum ions in soil moisture, neutralizing acidity and precipitating toxic aluminum into harmless hydroxides.
- Calcitic lime: Contains primarily calcium carbonate (CaCO3), ideal for soils with adequate magnesium levels.
- Dolomitic lime: Contains both calcium carbonate and magnesium carbonate (MgCO3), correcting both soil acidity and magnesium deficiency.
- Neutralizing value: Measured by Calcium Carbonate Equivalent (CCE); higher fineness grade ensures faster chemical reaction in soil.
Agronomic benefits of liming acid soils
Acid soils in coastal, high-rainfall, and northeastern Indian regions lock up applied phosphatic fertilizers and create aluminum and iron toxicity.
Applying agricultural limestone restores optimal soil pH (6.0 to 7.0), dramatically enhancing nutrient availability and microbial nitrogen fixation.
- Phosphorus unlocking: Neutralizing soil acidity prevents phosphorus from fixing with insoluble aluminum and iron complexes.
- Biological nitrogen fixation: Neutral pH promotes the survival and activity of Rhizobium nodulating bacteria in legume crops.
- Root development: Eliminates aluminum toxicity, allowing healthy taproots and feeder roots to penetrate deep into the subsoil.
- Target crops: Highly beneficial for pulses, groundnut, soybean, maize, sugarcane, and plantation crops.
Application methodology, timing, and soil test recommendations
The quantity of limestone powder required must always be determined based on a professional laboratory soil test and buffer pH analysis.
Incorporate lime into the soil 3 to 4 weeks prior to crop sowing or planting to allow adequate moisture contact and chemical reaction time.
- Application timing: Broadcast uniformly over plowed fields during pre-sowing land preparation and harrow into the top 15 cm of soil.
- Fineness specification: Use finely pulverized powder (passing 80-100 mesh sieve) for rapid neutralization.
- Soil health card linkage: Consult Soil Health Card recommendations to calculate exact metric tons of lime required per hectare.
Official source
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Soil Health Card Portal, Ministry of Agriculture ↗Related on KisanPe
Common questions
What is agricultural limestone powder used for?
It is used as a soil amendment to neutralize acidic soils, raise soil pH, eliminate toxic aluminum, and supply essential calcium.
What is the difference between calcitic lime and dolomitic lime?
Calcitic lime supplies calcium carbonate, while dolomitic lime supplies both calcium carbonate and magnesium carbonate.
How should limestone powder be applied to farm fields?
It should be broadcast evenly over moist soil 3 to 4 weeks before sowing and incorporated thoroughly into the topsoil with a disc harrow or rotavator.
General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.
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