- The plants frequently contain more Sulphur than Potassium, Calcium and Magnesium.
- Sulphur improves cereal qualities for milling and baking, marketability of copra, quality of tobacco, vegetables, onion, crucifers (cabbage, cauliflower, knol-khol, mustard), legumes, forage crops, etc. Obviously, if crop rotation is followed with these crops; the next crop requires addition of Sulphur in the field.
- Rains, industrial fumes, smokes, decaying organic matter, etc. return some amount of Sulphur in soil and air.
- Thawing cabbage fields emit Hydrogen Sulphide (H2S) gas. This is an evidence of abundant Sulphur content in cole crops. Onion and Garlic also contain Sulphur in appreciable quantities. Their pungency is due to presence of sulphurous compound – Allyl Propyl di Sulphide.
- It is absorbed in the plant system as Sulphate form (SO4). Then it goes into the production of Sulphur containing amino acids like Cystine, Methionine, etc. Just like Nitrates (NO3) are reduced before they can be used to form proteins, Sulphates must also be reduced to become a part of Sulphur containing organic compounds in the plant.
- Sulphur deficiency is found mainly in acidic soil. So also in coarse textured soils low in organic matter, in high rainfall areas and sites away from industrial activity.
- Optimum supply of Sulphur leads to increased uptake of Manganese and Zinc.
- Sulphur is a component of amino acids (Methionine and Cystine), which are the building blocks of proteins.
- It is an important constituent of thiamine, biotin, Acetyl Co-A, Ferredoxin, glutathione, etc.
- It plays important role in the synthesis of glycosides in mustard oil.
- It promotes nodule formation on the roots.
- It is involved in carbohydrate metabolism.
- Sulphur is a structural component of some amino acids (Methionine and Cystine) and vitamins, and is essential in the manufacturing of chloroplasts. Sulphur is also found in the Iron-Sulphur complexes of the electron transport chains in photosynthesis. It is immobile and deficiency therefore affects younger tissues first.
GENERAL DEFICIENCY SYMPTOMS
- The deficient leaves turn yellow and the veins are pale. But no necrotic spots are observed on the veins.
- The roots and stem become abnormally long and develop woodiness.
- The fruits do not mature fully and remain light green in colour. The forage crops contain undesirably wide C:N ratio and thus have lower nutritive value.