Wollastonite is a high-grade calcium silicate mineral containing 27% silicon, 16.5% calcium, and 4% magnesium and can be used as an amendment to soils to increase the level of mineral-borne nutrients and plant-available silicon. It can be applied at similar rates and using similar equipment as agricultural lime.
Carbon-neutral Calcium: When calcium carbonate (lime) reacts in 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: Although silicon is naturally abundant in soils, a very small percentage is plant-available, and continual cropping can reduce this amount. The silicon in wollastonite is in an amorphous form, meaning that in the presence of water it becomes available to plants as silicic acid.
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.
When grubs come into contact with wollastonite, their soft bodies are lacerated by the tiny needle-like crystals which leads to desiccation and death. This mechanical method of grub control is far less stressing on soils than chemical alternatives, and eliminates the risk of environmental damage due to pesticide runoff.
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.
Research has demonstrated positive effects of soil-applied wollastonite in the following crops:
|Cucurbits (squash, pumpkins, cucumbers, melons)||Delayed onset and reduced severity of powdery mildew, increased yields.|
|Cereal grains||Reduced lodging, higher protein, increased yields.|
|Corn||Increased stalk strength, reduced corn borer feeding.|
|Soybeans||Reduced incidence of downy mildew & increased resistance to stem canker.|
|Wheat||Delayed onset and reduced severity of powdery mildew, increased yields.|
|Tomatoes||Reduced severity of Fusarium disease and bacterial wilt, increased sucrose content.|
|Grapes||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.|
The following rates are suggested as general guidelines:
|Greenhouses||6 to 10lbs/cubic yard (1/4c./ga)|
|Gardens||1 cup/yard of row at seeding 2tsp. to 1/3 cup at transplanting 2tsp./plant topdressed|
|Vegetable Fields||1.6 to 4.4 t/ac broadcast 150 to 600 lbs/ac banded at seeding or transplant (according to crop family)|
|Field Crops||0.5 to 2.2 t/ac broadcast 300 to 500 lbs/ac banded|
|Turfgrass||1 to 1.75 t/ac|
|Lawns & Trees||50 to 80 lbs/1000 sq.ft. (33 ft x 33 ft)|
Canadian Wollastonite for agricultural and horticultural uses is available from these distributors: