Now is time to increase sulphur use
By Louise Impey
SOME areas of the UK are now receiving less than 15kg/ha of sulphur from the atmosphere, making supplementation with fertilisers essential to prevent yield loss, says Dr Mike Carver of Arable Research Centres.
"Oilseed rape is the indicator crop of a deficiency. It has a much greater requirement than cereals."
White flowers, small petals and shorter growing patches are the classic signs. "In trials in the Cotswolds in 2000, we recorded a 48% yield response when we applied sulphur to oilseed rape."
Cereals are not as responsive but yield boosts of 13% have been seen. "Sulphur is also implicated in breadmaking quality, so its worth checking levels," says Dr Carver.
Soil and tissue tests arent very accurate, he believes. "Measuring N and S levels in harvested grain is better, but any shortage cant be addressed until the following year. Theres also a new test available which measures the sulphur:malate ratio and allows growers to react within the same growing season."
ARC will be evaluating all four of the testing procedures at 34 sites in the coming year, helping growers find the best predictive method. "Theres great pressure to apply sulphur, but we must make sure there will be an economic response to it."
Ideally, sulphur should be applied in the sulphate form just as the crop is starting to grow in early spring. "You cant make a sulphur bank," says Dr Carver. "So it has to be applied every year once a deficiency has been identified." *