Sulphur content of winter wheat grain in long term field experiments

Sulphur is an essential element for both plants and animals. Decreasing sulphur deposition from the air, and the use of more concentrated phosphate fertilizers that contain less sulphur, has led to reports of sulphur deficiencies for winter wheat. Sulphur deficiency significantly effects production and quality of winter wheat. Sulphur deficiency decreases grain size and baking quality because of formation of disulfide bonds formed from the sulphydryl groups of cysteine. This effects the viscoelasticity of dough. The purpose of this study was to evaluate the effect of NPK fertilization on sulphur concentration in winter wheat grain on different soil types. We analyzed wheat grain, grown at various locations where fertiliser had been applied for many years in places throughout Hungary, for sulphur content. These experiments were conducted using the identical varieties and fertiliser treatments at eight locations. At a separate location, additional varieties were also evaluated. The sulphur contents of the grains were determined by using ICP-AES equipment. The sulphur contents of winter wheat varieties in Hungary averaged 1500 mg/kg and the difference between the varieties was as much as 120 mg/kg. The sulphur contents are influenced not only by sulphur fertilisers, but nitrogen fertilisers as well. Due to the strong N-S relationships, fluctuations in protein contents also caused decreases/increases in the sulphur contents of the wheat grain. The N-S relationship could be described by using a mathematical linear function. Annual applications of 100 kg/ha superphosphate, containing more than 10kg sulphur, provide sufficient sulphur to produce a 5 t/ha grain yield. This study suggests that a 1500 mg/kg value for sulphur content in winter wheat grain is sufficient to maintain good yield and grain quality.