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

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.