Don’t overlook the importance of sulphur

Sulphur (S) and nitrogen (N) go hand-in-hand when it comes to maximising grass production and sward quality during the grazing season.

In the past, S was overlooked as an essential nutrient to include in your fertiliser plan; but farmers are beginning to come to the realisation that S is just as important as N to the grass plant.

In addition to N, S is involved in protein synthesis in the grass plant. Both elements are the building blocks of amino acids which form plant proteins.

Importance of Sulphur

Sulphur is essential for the formation on amino acids, the building blocks for proteins which are needed for growth and development in plants and animals.

Again S is required to convert N to plant dry matter. As grass grows, both S and N are used together so a S deficiency will decrease nitrogen-use efficiency and so reduce yield.

Thus, S is an important nutrient for grassland and is closely associated with nitrogen uptake and efficiency.

Does my grass need sulphur?

If you feel you are not getting as much of a response from your N fertiliser as you should be, this may be a clear sign of S deficiency in the soil.

In addition, pale yellow leaves similar to what is observed when there is a N deficiency are an indicator. Although, it is usually more visible in younger plant leaves when associated with S.

The most effective way of accessing the S content of your grass is through a herbage analysis.

Sulphur fertiliser advice

The response to S fertiliser increases as the rate of N fertiliser increases.

  • Apply 20 kg/ha per or 16 units/ac year for grazed swards on a little and often approach starting in early spring;
  • For silage swards apply 20 kg/ha or 16 units/ac of S per cut;
  • Avoid over application of S as it will trigger a copper/selenium deficiency in livestock.