Sulphur is a constituent of three of the 21 amino acids which form proteins, and thus it plays an important role in both plant and animal nutrition.
Deficiency is commonly seen as yellowing of plants due to its role along with nitrogen in protein synthesis.
Impact Fertilisers’ Sulphur Products
Single Superphosphate (SSP)
P: 8.8% S: 11% Ca: 19%
SSP is ideally suited to top-dressing perennial pastures, where both phosphorus and sulphur are required.
Sulphate of Ammonia (SOA)
N: 20.4% S: 24%
Commonly used in combination with other nitrogen sources, such as DAP, MAP and Urea, to add sulphur to blends.
Sulphate of Potash (SOP)
K: 41.5% S: 17%
This product supplies potassium as well as sulphur. As it is considerably more expensive than MOP (Muriate of Potash), unless there are agronomic reasons (such as high soil chloride) as to why MOP should be avoided, then there are likely to be more economical sulphur containing fertilisers.
This sulphur fertiliser is 90% elemental sulphur plus a carrying or swelling agent, usually bentonite clay. Brimstone 90 is a dispersible elemental sulphur fertiliser. The granules disperse on wetting after application, to release fine sulphur particles.
Plants can only take up nutrients in an inorganic (chemical) form. Elemental sulphur, being in the organic chemical form, is not immediately available for plant uptake. It must first be oxidised to the sulphate (SO42-) form, through a process called mineralization which involves soil bacteria (Thiobacillus).
For this process to occur effectively the soil needs to be:
- Contain correct bacteria (Thiobacillus)
- In preferred pH range (low)
Elemental sulphur may be suitable for long term use or as a maintenance product. As elemental sulphur can reduce pH at high rates of application, it may be useful lowering pH for crops like Blueberries, where a pH (w) <5.5 is desirable.