Effects of sulphur application on grain yield and quality, and assessment of sulphur status in winter wheat (Triticum aestivum L.)

Winter wheat was grown in 26 field trials in Norway during the period 2004-2006. The main aim was to determine the effect of various sulphur (S) fertilization strategies at two different nitrogen (N) levels on grain yield and quality of winter wheat. With the exception of four trials in central Norway, all the trials were located in the south-eastern part of the country. Increasing the N fertilization from 170 to 210 kg N ha(-1) resulted in significantly higher grain protein content (GPC) and sodium dodecyl sulphate (SDS) sedimentation volume. On clayey soils in southeast Norway, increased N-fertilization also resulted in higher grain yield and lower test weight and thousand grain weight (tgw). Omitting S fertilization significantly reduced grain yields on sandy soils in southeast Norway and on loam and silt loam in central Norway, whereas no yield reduction was found on clay soils. SDS sedimentation volume and specific SDS (sSDS = SDS/GPC) were significantly reduced when S-fertilization was omitted. GPC was reduced by S fertilization in central Norway. Generally there were no significant responses at application rates higher than 12 kg S ha(-1). The malate: sulphate method is a field-based diagnostic test used to determine whether S deficiency is likely to occur. The results did not indicate that this test is reliable under Norwegian conditions. On the other hand, the use of a chlorophyll meter measurements to assess S status gave promising results.