Calcium silicate proven superior to lime – pound for pound

January 3, 2023


Finding studies that look at the big-picture impact across longer time scales can sometimes feel like looking for the needle in the haystack. This study is one of those needles, with many different angles summarized succinctly. This is the only study we have found testing wollastonite and lime in a no-till production system.

This research looked at a wide variety of variables in comparing lime and a calcium-magnesium-silicate slag with similar properties to wollastonite (wollastonite does not have high levels of heavy metals slag has). This study looked at the effects of liming with lime and calcium magnesium silicate over an 18-month period throughout the soil profile to a depth of one meter.


  • Calcium magnesium silicate changed soil pH faster than lime
  • Calcium magnesium silicate neutralized soil pH further down in the soil
  • Increasing soil silicon levels were shown to increase P concentrations in the crops compared with the lime application
  • Silicon was shown to bind excess aluminum throughout the soil profile

The phosphorus finding is interesting and includes a reference to another Spanish study which, unfortunately, we could not access. The authors suggest that silicon out-competes phosphorus for anion-binding sites on soil colloids, keeping more P in the soil solution for plant uptake. This implies that silicon increases the fertilizer efficiency of phosphorus; for every pound of phosphorus fertilizer applied, more goes into the plant, and less is left in the soil. An important finding for a world rapidly running low on phosphorous fertilizers.

Read the full study here and more in our agricultural research database.