Changes in the sulphur status of British wheat grain in the last decade, and its geographical distribution

In 1992 and 1993, respectively, 400 and 393 wheat grain samples were collected representatively from the major wheat-growing areas in Britain. Concentrations of S in the grain and the N:S ratios were determined, and the variations due to variety and geographical distribution were analysed. Grain S concentration ranged from 0.54 to 2.09, with a mean of 1.43 mg g(-1) in 1992, and from 0.80 to 1.67, with a mean of 1.26 mg g(-1) in 1993. The ranges of grain N:S ratio were 13.3-29.6, with a mean of 15.8 in 1992, and 11.5-25.9, mean 15.6 in 1993. Breadmaking varieties contained significantly greater N and S concentrations in the grain than other varieties, but only small differences were found in the N:S ratio in grain. In 1992 and 1993, 7 and 26% of the samples had a S concentration below the critical value of 1.2 mg g(-1), respectively, whereas 10 and 7% of the samples had an N:S ratio greater than the critical value of 17. In both years 2.5% of the samples satisfied both criteria of S deficiency. Comparison of the results of 1992-1993 with those of 1981-1982 (Byers et al, J Sci Food Agric 38 (1987) 151-160) showed a significant decrease in the S status of British wheat grain during the 10-12 year period. The decrease can be attributed mainly to decreased S inputs, particularly from atmospheric deposition. The pattern of geographical distribution of grain S concentrations was not as strong as it was in the 1982 survey. However, it was still apparent that grain samples with small S concentrations were located mainly in Scotland, northern England, and the west and southwest of England, whereas the largest S concentrations occurred mainly in the areas near to or down-wind of the industrial conurbations of central England.