24 July 2002

S lack may be hidden

WHEATS dont need to display sulphur deficiency to suffer yield loss, and supplies from livestock manures cannot be relied on to avoid the problem, warns Masstocks David Langton.

"Lack of visual deficiency symptoms doesnt necessarily mean there is no yield penalty." Trials last year found that loss could be as high as 0.6t/ha in apparently healthy crops receiving inadequate sulphur.

It is not just yield which is affected, he adds. "There is a lot more evidence now that baking and protein quality suffers in crops not getting enough sulphur.

"Organic manures do deliver sulphur. But for the peak demand at stem extension they may not break down fast enough to allow the plants to pick it up."

lGrowers lose £30m a year by not detecting sulphur deficiency early enough, but the new malate:sulphate ratio test developed at Rothamsted Research can help overcome this, according to the HGCA. &#42