Why use sulphur on grass

Published 26 March 15

These days there aren’t many places where you won’t see a sulphur (S) response in grass, although lighter soils or younger swards will show the greatest, says Elaine Jewkes from the BGS.

As well as increased herbage DM yield, sulphur use can improve grass protein and sugar content. Nitrogen use efficiency can also be improved, with a knock-on environmental benefit – if N has been used, it’s not there to be lost by leaching or denitrification, making losses to the environment smaller.

It is important to measure what you have already and you can get grass analysed for N and S content. If the S content is below 0.25% it is lacking but don’t push the S content too high though, the top end of normal is 0.4%.

How much sulphur should I apply?

Sulphur is crucial on cut swards, where the large offtake of grass removes lots of nutrients. Apply up to 40kg/ha SO3 per cut. First cut may not always give a response but in recent years there has been early S deficiency, especially after very wet winters; second and third cuts are a must.  There is no reason not to get the same benefits on grazing land; apply a modest amount as an N:S fertiliser (or NKS if required) from late April/May. Most N:S or NKS fertilisers will supply 14-18kg SO3/ha at  N rates commonly used mid-season and this is plenty.