Sulfur is an important trace element in agriculture because it is required for the production of amino acids, the precursor to proteins. It is also used in photosynthesis and chloroplasts development (the “organs” within cells responsible for chlorophyll production). Sulfur fertilisers come in two forms; thiosulfates or elemental sulfur and sulfates. Thiosulfates and elemental sulfur release sulfur slowly because it must first be oxidised to the usable sulfate. These products become more available for maximum plant growth in spring and are not lost by leaching. Sulfates however are immediately available to the plant, meaning visual deficiencies can be corrected but also that the nutrients can be lost in a heavy rainfall event. It is recommended that fertilisers with both fast and slow release of sulfur be used.
Sulfur deficiencies have become more common in recent years due to the stricter controls on sulfur atmospheric emissions and increases in crop sulfur removal. Sulfur and nitrogen deficiencies are similar in that they both cause the yellowing of leaves, however this occurs in the younger leaves if there is insufficient sulfur and the older leaves if there is insufficient nitrogen. Sulfur deficiency also causes the plant to turn rigid and brittle and the stems to remain very thin. It is most common in sandy soils and wet conditions, where the sulfate leaches below the roots, becoming unavailable.
The important role of sulphur in soils | Summit Fertilizers. Summitfertz.com.au. (2022). Retrieved 10 February 2022, from https://www.summitfertz.com.au/field-research-agronomy/sulphur.
Mclaughlin, M. (2020). Technical Bulletin: Sulfur in Soils [Ebook]. The University of Adelaide. Retrieved 10 February 2022, from