How particle size of agricultural lime affects reactivity in soil
At this year’s AgriScot event in Edinburgh, the LKAB Minerals agriculture team met a wide range of distributors, agronomists, and farmers to discuss soil health and calcium management. One recurring topic was why granulated lime can be applied at much lower rates than agricultural lime alone, while still delivering a rapid lift in soil pH.
Why particle size matters
Soil pH is driven by the concentration of hydrogen ions. When lime (calcium carbonate) dissolves in the soil, calcium attaches to soil particles and displaces acidic cations (H⁺). The carbonate then reacts with hydrogen ions, forming CO₂ and water. This reduces soil acidity and increases pH.
The speed of this reaction is strongly influenced by particle size. Finer lime particles provide a much larger surface area for reaction, which means they neutralize acidity more quickly. Research shows that limes with a high proportion of particles below 0.5 mm deliver faster pH correction – important when addressing acidic soils or maintaining optimum nutrient uptake. This is why agricultural lime with finer particle sizes is more reactive than coarser alternatives.
How Calcifert granulated lime works
Calcifert granulated lime is produced from ultra-fine particles (less than 150 microns) formed into 2 – 6 mm granules. These granules rapidly disperse on contact with moisture, releasing the fine particles and exposing a significantly larger surface area to the soil. This drives quick dissolution and fast reactivity.
A simple way to visualise this is to think of a classic Rubik’s Cube. As a complete cube, the outer surface area is limited. Break it into its 27 individual cubelets, and the total surface area becomes three times greater. The same principle applies to lime: when granules break down into much smaller particles, the reactive surface area increases dramatically.
Lasting impact on pH
Trials show that using fine particles not only provides rapid correction, but can also give a more persistent pH effect compared to coarser materials. And because Calcifert can be applied at low annual maintenance rates, it offers a convenient way to keep pH at the optimum level for nutrient use efficiency and yield performance.
When it comes to lime, particle size does matter – and using agricultural lime with fine particles is key to achieving fast, effective results.
For more information about Calcifert, contact the LKAB Minerals agriculture team. You can also follow us on LinkedIn for the latest updates, case studies, and product releases!
