How silica helps to improve overall plant health
Silica is one of those elements like oxygen, carbon and hydrogen that is often taken for granted. It is a major element in the Earth’s crust and most soils. Silica is an abundant element in sandy beaches, in veins of quartz crystals, and granite boulders. Molten silica is used to make glass, due to its chemical structure to add rigidity.
Silica (silicon dioxide) forms when silicon comes into contact with oxygen. Sand, silt, and clay generally have high concentrations of silica. Abundant in soils, silica is a major part of plant tissue, found in plant cells at higher concentrations than nitrogen and potassium, two major macronutrients. Most scientists do not consider silica an essential nutrient or vital to plant survival, although this element provides many plant benefits.
Silica strengthens cell walls, reinforcing cell walls by making them thicker and stronger. Weak cell walls do not provide the plant enough support, so strengthening cell walls helps a plant grow thicker, reinforced branches and stems that can support the weight of higher yields. Thicker stems and stalks can increase water and nutrient uptake which translates into faster growing healthier plants. Silica simply adds rigidity to the plant cells so they can grow healthier.
One major benefit of plant silica is its ability to resist environmental stress. Silica helps plants withstand extreme temperatures, both hot and cold.
Silica supports plants during hot mid-day temperatures and very low night time temperatures, helping plant survive both droughts and frost. Silica reduces the loss of water by transpiration from a plant cell by forming a protective mineral coating inside the cell. By losing less water, plants can survive low moisture conditions or periods of dry soils along with higher temperatures. During periods of cold, the stronger cell walls resist rupturing during the stress of freezing water. Adequate silica concentrations in plant cells allows plants to survive extreme conditions.
Silica also enhances the plants immune system from disease and insect attacks by acting like a super vitamin. Soluble silica, that is foliar applied to plant leaves, reduces fungal spores and fungal infections like pythium and powdery mildew. Silica forms a mineral barrier inside the plant leaf, so the plant can resist many plant pathogens, diseases, and even insect attacks. Biting and sucking insects find it harder to penetrate the leaf when a silica barrier exists.
Plants with adequate silica have a higher metabolic activity due to increased plant chlorophyll. Silica may enhance the uptake of magnesium, which is the central element in making chlorophyll. Plants high in silica can utilize carbon dioxide more efficiently for improved photosynthesis and this combination (higher chlorophyll, better use of carbon dioxide) results in healthy green foliage with strong leaves, stems, and stalks. Overall, plant health improves so it can tolerate moisture, heat, and cold stress better than plants with lower silica concentrations.
Silica is needed by healthy plants from seedling stage to harvest or throughout its entire life cycle. Most silica is taken in through the roots in a soluble form, but soluble forms of silica may not always be available, especially in sandy soils. Once silica is absorbed into a plant cell, it’s highly immobile. Early uptake of silica in a plant’s life cycle helps a plant reduce its exposure to leaf wilt, plant shock, and leaf curl.
There are two major forms of agricultural silica: potassium silicate and silicic acid. Silicic acid, as a weak acid, can easily be added to a foliar spray due to its small effect on solution PH. Potassium silicate as a foliar spray gives the added benefit of stomatal transpiration of both elements (potassium and silica).
Silica changes the leaf physical structure to stop the attachment of fungal spores and some soft-bodied insects. At an early age, healthy plants use small amounts silica at low concentrations but both the concentration and the total of amount of silica utilized in healthy plants increases with maturity.
In greenhouses and in hydroponics, silica is a common element added to improve leaf, stem, and stalk strength. Silica is one of those elements that we take for granted. Maybe, due to all its benefits, we ought to consider how silica could be added as a fertilizer nutrient. While most silica is taken up by roots, it is another element that can be foliar fed and absorbed by leaves. As with any element, too much silica can cause leaves to become too rigid and too brittle.
For plants experiencing environmental stress (drought, high temperatures, cold), fungal disease, insect infestations, etc., adding silica to fertilizer solutions might be a worthwhile to get healthier robust plants. Adapted from an article by Helen Isbell.