We continue with our series of articles about the biochemical sequence necessary for healthy plant growth. The biochemical sequence is an explanation of the cycles, and the roles that biochemicals play in the development of plants. You can read back on this blog about the fascinating interplay of boron, silicon and calcium.
In these previous articles, I’ve drawn the analogy that when it comes to their roles in healthy plant growth, boron is like the driver, silicon is the highway and calcium is the truck. To continue the comparison, the fourth element in the sequence, sulphur, can be likened to the key in the ignition. Sulphur, represented on the periodic table by the symbol S and bearing the atomic number 16, is an abundant non-metal element, and it is the classic catalyst in organic chemistry. When it comes to plant growth, nothing – not even boron, would work without sulphur. Here are some of the key functions that sulphur is involved in:
- Is a key soil anion and reacts with both calcium and silicon which are the opposite poles of life chemistry.
- It is an essential plant nutrient that that improves the efficiency of other plant nutrients, particularly nitrogen and phosphorus.
- Sulphur works directly with nitrogen, enabling the conversion of nitrate nitrogen in the plant to amino acids, and supporting basic carbohydrate metabolism in the plant.(Nitrate is a proven Carcinogenic)
- Required for the formation of chlorophyll
- For healthy growth and optimal yields, plant require sulphur in similar quantities as they do phosphorus
- Sulphur is the fourth major nutrient in terms of volume the plant requires and probably the most neglected. More importantly without sulphur organic chemistry will not function to its fullest potential
- Sulphur is essential component in vitamins and enzymes
- The lists of benefits are extensive because Sulphur is essential as a classic catalyst in organic chemistry and therefore should be No 1 and starting point for soil corrections!
Despite its vital role, sulphur is one of the most neglected plant nutrients, particularly in conventional farming where the focus is narrowly set on nitrogen, phosphorus and potassium. By contrast, Avondale’s holistic BioLOGIC® approach ensures that we pay attention to the full spectrum of macro- and micro-nutrients involved in healthy plant nutrition, and therefore we monitor the presence of sulphur in our soils. In the Western Cape, most of our agricultural soils are hugely deficient in sulphur and when you combine the fact that Sulphur is second only to Nitrogen form a leachability perspective the problem compounds itself.
In soil tests we are looking for a minimum amount of 30 to 50 ppm taking into account the plant removal and how leachable the element is. Sulphur is found naturally in volcanoes and hot springs, there are many great natural sources of sulphur. We the soil sulphur requirements in the forms of gypsum, elemental Sulphur (Much slower release and relies on soil life, great for easy leachable soils) and volcanic ash. However, a great way to increase sulphur in your soil is to ensure that it contains large amounts of organic matter that supports large communities of Sulphur fixing bacteria which in turn releases plant-available sulphur through mineralisation.