Supply and nutrient demand of sugar beet for sulphur

Sulphur deficiency in arable crops is discussed due to decreasing sulphur immission. This study aimed at assessing the recent supply and the effect of sulphur application on yield and quality of sugar beet. A survey on farms showed regional differences in the sulphur supply. The Smin amount considerably exceeded 20 kg/ha (0-90 cm), the sulphur concentration in young leaf blades in most cases was more than 0,35 %. There was no relationship between Smin and sulphur concentration in leaves. In an in-situ-incubation a net sulphur mineralisation of 42 kg/ha in 0-30 cm was determined under sugar beet from April to October. At 21 sites sulphur application had no positive effect on yield and quality of sugar beet in 1996 and 1997. The sulphur uptake of 24 kg/ha (8-10 kg/ha by beet) was markedly lower than the sulphur amount released within the vegetation period. In pot experiments a threshold value between 0,30 and 0,35 % sulphur was determined. These results lead to the conclusion, that at that time there is no need for sulphur application of sugar beet.