The trend of using sulphur has recently declined for both arable and grassland farmers. Whilst product availability has changed, it is essential that we do not neglect the importance of sulphur.
Historically ignored, as it was expected that requirements would be met with atmospheric S in the rain. However, the risk of S deficiency is increasing due to the 82% reduction of atmospheric S emissions over the last 25 years due to the 1993 Clean Air Act, subsequently reducing S deposits to 5-10kg/ha.
Sulphur has a strong co-dependent relationship with nitrogen. Along with nitrogen, sulphur forms amino acids necessary for protein synthesis, which then also improves nitrogen use efficiency.
Sulphur deficiency shows itself in cereals and oilseed rape with stunted growth and yellowing (chlorosis) of the leaves, first showing on the younger leaves due to sulphur’s immobility within the plant. This is opposed to N deficiency, which will show in the lower older growth first.
RB209 recommends that where an S deficiency has been detected in cereals, 25-50kg/ha SO3 should be applied as a sulphate-containing fertiliser between early March and the end of April.
