Soil Amendments 

Wollastonite is a high-grade calcium silicate mineral containing 27% silicon, 16.5% calcium, and 4% magnesium. The mineral is available in a number of formats for use as a soil amendment and can be applied at similar rates and using similar equipment as agricultural lime. Detailed information is available on the product label.

Silicon is recognized as a “beneficial substance” or ” quasi-essential” element for plant growth by The International Plant Nutrition Institute. Different plants accumulate silicon at different rates: monocots, including grasses, sugarcane, and cereal crops, along with a few dicots, are silicon accumulators. These plants show beneficial effects to added silicon, particularly under stressful conditions.


Features and Benefits:

Carbon-neutral Calcium: When calcium carbonate (lime) reacts in the soil, it releases carbon dioxide. Wollastonite breaks down into calcium and silicon, and is therefore carbon neutral. Like lime, the calcium helps balance soil pH and supplies calcium for plant growth.

Plant-Available Silicon: The silicon in wollastonite is in an amorphous form, meaning that in the presence of water, it is available to plants as silicic acid. Although silicon is abundant in the soil, a very small percentage is plant-available, and continual cropping can reduce this amount.

Promoting Plant Health: Silicon is important to a plant’s passive and active resistance to environmental stresses, pests and disease. Silicon strengthens cell walls, reducing lodging, increasing drought resistance, discouraging the feeding activity of sucking and biting insects, and resisting infection by fungal pathogens. Silicon is an essential element in the production of phytochemicals which plants use to defend against attack and to communicate the presence of threats to other plants.

Protecting Seeds and Roots: At the microscopic level, wollastonite has an acicular (needle-like) crystal structure. Recent field trials and ongoing research show that when wollastonite is applied as a soil amendment, it reduces grub pressure in turfgrass.


Research has demonstrated positive effects in the following crops. Links to full studies are available on our research page.

Cucurbits (squash, pumpkins, cucumbers, melons): delayed onset/reduced severity of powdery mildew, increased yields
Cereal grains: reduced lodging, higher protein, increased yields
increased stalk strength, reduced corn borer feeding
Soybeans: reduced incidence of downy mildew & increased resistance  to stem canker
Wheat: delayed onset/reduced severity of powdery mildew, increased yields
Tomatoes: reduced severity of Fusarium disease and bacterial wilt, increased sucrose content
increased Brix (sugar/mineral content), reduced fungal disease
Turfgrass: increased yield and quality, reduced powdery mildew
Flowers: decreased bract edge burn, increased shelf-life in poinsettia; decreased powdery mildew in zinnia, sunflower, and phlox; enhanced flower size of gerbera; increased resistance to metal toxicity and fewer aphids in zinnia.

Nutrient Management: Studies have also demonstrated wollastonite’s ability to adsorb water-soluble phosphorus and immobilize heavy metals; indicating further potential for this soil amendment to enhance soil and water quality.

Canadian Wollastonite continues to invest in research to demonstrate and measure the benefits of this mineral. Check our blog for the latest news!

Regulation and Oversight

In Canada, Health Canada’s Pest Management Regulatory Agency categorizes calcium silicate as a “List 4A” formulant, the level of least concern, reserved for substances “which are generally regarded to be of minimal toxicological concern, as well as substances commonly consumed as foods.”

In the United States, the Food and Drug Administration considers calcium silicate to be “Generally Recognized as Safe.” The U.S. Environmental Protection Agency considers calcium silicate to be exempt from the requirement for a residue tolerance level if used in accordance with good agricultural practices when applied to both growing crops or raw agricultural commodities after harvest and animals.