The effect of sulphur fertilisation on yield and herbage composition was investigated in two successive years at two grassland sites, one with ryegrass and one with ryegrass/ clover, where the available sulphur in the soil was less than 10 mg kg-l. When supplies of N, P and K were not limiting, herbage yields increased with added sulphur at both sites, particularly at the second and third cuts and in the second year. Sulphur additions also increased the concentrations of total S and so42--s in the crop, and reduced the N: S ratio. The figures for these parameters in herbage from control plots confirmed that low yields in the presence of normal nitrogen fertilisation were probably caused by sulphur deficiency.

WILLIAMS et a1.-PHOSPHATE SORPTION I N SOILS 551 9. Germination tests have shown that beans which are alive when taken from the heap can die on the drying mats, providing further support for the theory that many of the changes occurring during fermentation continue in the drying stage. Acknowledgment this work.

No abstract

The relationships of the amounts of sulphate extracted by different extractants with the yield, response to added sulphate, and the sulphur uptake of oats in pot cultures have been studied for ten acid soils. The L-value, representing the quantity of isotopically exchangeable sulphur sampled by the plants, was estimated using radioactive sulphur. The best relationships with the crop variables were given by sulphate extracted with calcium chloride, potassium dihydrogen phosphate and sodium bicarbonate. Critical values, below which a response to added sulphate is likely to be obtained under the pot conditions, are given for the phosphate and bicarbonate extractants.

Sulphur deficiency reduced the yield and sulphur content of ryegrass at the fourth cut, while increasing the nitrogen content and N:S ratio. The distribution of the forms of nitrogen was also altered, with a decrease in the proportion of nitrogen recovered as amino acids and an increase in the concentration of asparagine. Amino acid analysis showed that the concentrations of the sulphur-containing amino acids cyst(e)ine and methionine were depressed by sulphur deficiency as well as those of arginine, histidine, lysine, glycine, leucine, serine and threonine. Sulphur deficiency, therefore, decreases the quality of crude protein found in grass, as well as reducing the yield.