Cultivation Chemistry: Micronutrients – Sulfur
It smells like rotten eggs and in its elemental form conveys a pale yellow color. Did you know that sulfur (S) is a critical component in cannabis cultivation? Let’s find out what’s going on under the surface.
When producing proteins, cannabis requires sulfur which makes constitutes around 90% of the nutrient uptake. The primary amino acids featuring sulfur are cystine, methionine and cysteine, which contain 90% of plant sulfur2. This nutrient, sometimes referred to as the “4th Macronutrient”, is a component of the amino acids that make up the proteins3.
Sulfur is predominantly found as sulfate in soils but is subject to leaching due its solubility in water. It is metabolized by cannabis from sulfate or sulfur dioxide and used to build organic molecules4.
Because sulfur plays a role in protein synthesis and chlorophyll, deficiency is similar to nitrogen. Sulfur has some mobility in plants and deficiency will show up in younger leaves followed by older leaves if left untreated unlike nitrogen deficiency which affects older leaves first.
To correct sulfur deficiency, add additional sulfur in the sulfate form to the growing media. Toxicity is rare even if excess is added.