Nitrogen to sulphur ratio in rapeseed and in rapeseed protein and its use in diagnosing sulphur deficiency

Abstract

This study investigated the variation of nitrogen to sulphur ratios in rapeseed (N/S)_t and in rapeseed protein (N/S). Under S‐sufficient conditions the (N/ S)_t ratios varied considerably between different varieties, with low glucosinolate varieties having higher ratios than high glucosinolate varieties. In contrast, (N/S)_p remained relatively constant at about 11.5 for all varieties tested, though significant effects of N and S nutrition on the (N/S) ratio were present. The ratio increased in the S‐deficient samples. Results of yield responses to S fertilizer and (N/S)₍from six field experiments were used to see if (N/S)_t could indicate the S status of the crop. Although yield losses due to S shortage tended to occur when (N/S)_t was greater than 10, the relationship was not sufficiently reliable for use in diagnosis.