Optimum timing for sulfur application in winter wheat with respect to cropyield and quality

Between 1995 and 1997, we have conducted 32 fertilizer trials with sulphur (30 kg/ha S plus 60 kg/ha N as Ammonium Sulphate Nitrate BASF 26) at variou s sites in Germany to determine the optimum timing of a sulphur application for winter wheat (beginning of vegetation, growth stage 30/32 or growth st age 49/51). The summarized results are: 1. Averaged over 32 fertilizer trials, a sulphur application at the beginni ng of vegetation or at growth stage 30/32 resulted in a significant yield i ncrease compared to N application only. Sulfur application at growth stage 49/51 had no effect on crop yield. 2. Depending on the weather during the trial year, the highest yield increa se was obtained with sulfur application at the beginning of vegetation when temperature and precipitation in winter were above average (here: 1995), a nd with sulfur application at growth stage 30/32 after a cold and dry winte r (here: 1996). 3. Sulfur application - regardless of timing - had no effect on the crude p rotein content. 4. On the basis of the found S-min-values, neither the necessity of a sulfu r-application nor the optimal date of sulfur-application could be prognosed .