Nutrients and their impact on healthy plant growth – Si is for Silica

Avondale’s holistic BioLOGIC® approach ensures that we pay attention to the full spectrum of macro- and micro-nutrients involved in healthy plant nutrition. In the Periodic Table, nature has a rich palette of elements that it rather delicately draws on to achieve fertile soils and healthy plant growth and over the next couple of posts I will be focusing on one element at a time.

I started this series of posts about the impact of nutrients in the soil on healthy plant growth with Boron, which is the activator of an essential biochemical sequence on which plants depend.  The next element on the Periodic Table in this sequence is Silica, sometimes also referred to as Silicon, bearing the symbol Si.  Following oxygen, Silica is the second most abundant element in the crust of the Earth, and it is an essential element in biology.  Research into plant growth has shown that it is present in significant amounts in the epidermal cells of plants and it plays several vital roles in plant metabolism.

You may remember that in my previous post in this series, I likened the role of Boron to the functioning of a vehicle’s plant's) 'steering wheel’.  Well, to continue the analogy, one can view Silica as the potential highway.  Whether one has sufficient plant-available Silica in the soils can be the difference between travelling on a gravel road versus the autobahn.  Silica plays a major role in building cell structure and cell strength. So if you have a deficiency in plant-available Silica you might have all the correct quantities of other nutrients but your transport system is not up to scratch, which of course means that your flow of nutrients from the soil via roots to leaves and back down is not effective.

Sufficient Silica is known to make a great impact on a plant’s structural integrity.  It can also improve a plant’s drought-, frost- and pest resistance.  It enhances the vigour of a plant, improving its root mass and increasing the above ground biomass, including the crop yield.

As a plant nutrient, Silica should be hard for the farmer to ignore.  Yet, many conventional farmers, with their narrow focus on Nitrogen (N), Phosphorous (P) and Potassium (K), have little or no idea that Silica plays such a great role in plant nutrition. There’s also the common perception that because soil is to a large degree made up of Silica, it is not necessary to consider supplementing it. However, the issue is that this Silica is not available to the plant. For interest's sake, legumes and specifically Medics, clovers and the like, foster acidic conditions around their root systems which help to solubilise the fixed silica rock. Our cover cropping system makes extensive use of legumes to help us with this.

At Avondale, we work with the full spectrum of nutrients in the soil and strive to achieve balanced the plant nutrition that is so important to healthy grapes and fine wine.  We test for the presence of Silica in our soils both in the total and available form. Where necessary we apply Silica from natural diatomaceous earth sources as well as liquid Silica (I’ll share a recipe for this at a later stage).  Silica is also very useful as a foliar spray remedy for powdery mildew.  Silica from a natural source and in a healthy environment is easily digested by the micro-life in the soil, making it wonderfully accessible to plants.

In the biochemical sequence, in its role as a super-highway for optimal plant nutrition, Silica is vital for carrying that other essential element, Calcium, which will be the next topic in this series of posts.