Spring wheat (cv. Kleiber) was grown in three pot experiments in a soil containing 10 mg kg-1 KH~P04-soluble sulphur with different rates of nitrogen and sulphur fertilisers. Without added S the yields of grain dry matter and crude protein were either unchanged (glasshouse experiment) or significantly decreased by the N treatments (controlled environment experiments). With added S the N fertiliser increased the yields by 4&110%. The experiments produced grain with a wide range of N and S contents, the latter ranging from 0.06-0.21 % on a dry matter basis. Grain from treatments giving the largest yields of dry matter and crude protein had a N: S ratio of about 15. The amino acid composition of the whole grain was changed significantly by the fertiliser treatments. When plants were grown without added S at the highest level of N the grain contained less than half the amount of cyst(e)ine and methionine (as % of total amino acid content) found in grain from plants given adequate amounts of S fertiliser. Grain from S-deficient plants also had a much greater content of aspartic acid + asparagine but less threonine, leucine, isoleucine and lysine. The N: S ratio in grain from plants grown with insufficient S was well in excess of 15. The relation of these findings to the nutritive value of wheat as a feed and to the provision of enough disulphide bonding capacity for its use in bread-making are discussed. Our results emphasise the necessity for having an adequate amount of S to balance the larger N applications now given to wheat to ensure that the grain is of the highest quality possible with any particular cultivar.

SummarySoils were analysed from two long-term liming experiments on a sandy-clay loam at Rothamsted and a loamy sand at Woburn. Plots given four levels of limestone factorially combined with phosphate and potassium fertilizers (with magnesium subplots in 1974) were cropped with beans, barley, potatoes and oats from 1963 to 1974.The smallest limestone applications (5 t CaCO3/ha) increased soil pH the following year to values predicted by lime-requirement determinations using a standard advisory method. The larger limestone applications (10 and 20 t/ha) increased pH proportionally less. Soil pH decreased after the first year with 5 t/ha in both experiments but increased at the 20 t/ha rate for 6 years in the sandy-clay loam and for 3 years in the loamy sand before starting to decline.Exchangeable calcium (soluble in N ammonium acetate) decreased at approximately linear rates in all plots of both experiments from the first year. Slopes of the regressions were smaller at low than at higher rates of liming, depending primarily on the average pH. Rates of CaCO3 losses from the surface 23 cm of soil ranged from 225 to 823 kg/ha per year at Rothamsted and from 307 to 852 kg/ha per year at Woburn.Observed rates of Ca loss were compared with an empirical relationship suggested by Gasser (1973) between annual Ca losses and soil pH under average rainfall conditions and estimates based on a model system.

In a controlled-environment pot experiment sulphur fertilisers increased the yields of ryegrass when large dressings of nitrogen were also given. Yield responses to sulphur occurred when the dry matter contained less than 0.20% S . At the third cut, sulphur deficiency decreased concentrations of reducing sugars but had little effect on sucrose and fructosan in the grass dry matter. Only 44% of the nitrogen in the most sulphur-deficient grass was protein-N as compared to over 80% in non-deficient grass. The non-protein-N accumulated predominantly as amides especially asparagine. The amino acid composition of the insoluble protein, including the proportions of cystine and methionine, was unaffected by acute sulphur or nitrogen deficiencies.

Calcium chloride giving 253 kg CI ha" was applied to the 20-inch and 40-inch 1/1000 th acre drain gauges after drainage restarted in 1974. It was taggedwith *

SUMMARYIn an 8-year field experiment, potassium sulphate and to a lesser extent magnesium sulphate increased yields of all crops both when applied alone and together. Although K/Mg interactions did not affect yields they considerably affected the ratio of concentrations of these elements in the dry matter of the crops. Sodium chloride increased yields of kale but not of barley harvested at ear-emergence.Percentage yield response to potasium followed the orderPotatoes (218%) < clover = barley < sugar beet < kato; < ryegress (17%).Magnesium increased yields from 3 to 10%, most with potatoes.Changes in exchangeable magnesium in the soil reflected differences between applied magnesium and crop uptakes. Changes in exchangeable potassium were less than expected, probably because non-exchangeable potassium was released on plots without added potassium and ‘fixed’ in non-exchangeable forms on plots where much fertilizer potassium had been given.Increase in the incidence of magnesium deficiency symptoms reported recently in South. East England are attributed to the local liming materials containing only small amounts of magnesium and to less F.V.M being applied to crops than previously.