Importance of Sulphur as a Plant Nutrient :
Sulphur (S), along with calcium and magnesium, is one of the three secondary nutrients required by plants for normal, healthy growth. The term secondary only refers to the quantity and not the importance of a nutrient. A deficiency in a secondary nutrient is just as detrimental as a deficiency in nitrogen, phosphorus or potassium. Sulphur is often overlooked and under-appreciated in importance. There is a significant balance between nitrogen and sulfur. Without enough sulfur, plants cannot efficiently use nitrogen and other nutrients to reach their full potential.
Functions of Sulphur :
Plants acquire sulphur from the growing medium as sulpate. Sulphate is readily soluble and subject to loss by leaching. Plant metabolism reduces sulphate and sulphur dioxide to forms that can be used to build organic molecules. Sulphur is a vital part of all plant proteins, and certain plant hormones. It is also used in the formation of certain oils and volatile compounds found in the onion and garlic family.
Sulphur Deficiency :
Since sulphur is associated with the formation of proteins and chlorophyll, its deficiency symptoms resemble those of nitrogen. Sulphur is moderately mobile within the plant, therefore deficiency symptoms usually start on the younger leaves and progress over time to the older leaves, resulting in plants becoming uniformly chlorotic. While sulphur deficiency symptoms on an individual leaf look like those of nitrogen, nitrogen deficiency begins in the lowest leaves, not the newest.
Sulphur toxicity :
Sulphur toxicity is very rare and will most likely not occur even if excessive sulphuric acid is injected to neutralise water alkalinity. High sulphur levels in the growing medium can compete with and induce nitrogen deficiency.
Effects of Sulphur on Plant Growth :
Sulphur is essential in the structural & enzymatic components in plants. Sulphur is a key component of some essential amino acids and is needed for protein synthesis. Chlorophyll synthesis also requires “S”.
Sulphur is not readily translocated within plants so all plants need a continuous supply of sulphur from emergence to maturity. In sulphur deficient plants, older leaves may appear more healthy while newer leaves & tissue may have stunted growth and a lighter green or even yellow appearance.
A sulphur deficiency at any growth stage can result in reduced crop growth & yield. Adequate “S” results in rapid crop & early maturity.
Dose & Application :
500g to 700g per acre.