Effect of sulphur fertilizers on the grain yield and sulphur content of cereals

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Abstract
In order to determine whether cereal crops require fertilizer sulphur (S) in areas estimated as receiving < 20 kg S/ha per year from the atmosphere, the effects of applying agricultural gypsum (10, 20, 30, 40, 60 and 80 kg S/ha), ammonium sulphate (24 and 48 kg S/ha) and foliar-applied elemental S (10 kg S/ha) fertilizers were compared with a nil-S control in replicated field experiments at 12 sites in England and Wales during 1987–90. Averaged across all S treatments, significant (P ≤ 0·01) positive yield responses of 0·4 t/ha were obtained in winter barley at three sites in 1990 on sandy soils in Wales (two sites) and in south-west England (one site). There was no yield advantage in applying > 10 kg/ha of S as gypsum at these sites. Yield responses were best predicted by a nitrogen: S concentration ratio ≥ 17:1 in leaf tissue at anthesis and a S concentration of ≤ 0·1% in the grain dry matter at harvest.Significant increases in total S and sulphate-S concentrations in leaf tissue at anthesis were obtained from increasing the rates of gypsum applied at ten of the sites, but a significant increase in the concentration of S in the grain at harvest was obtained at only one site. There was no difference in effectiveness between gypsum and foliar-applied elemental sulphur when compared at a single rate of 10 kg S/ha. Comparison of the increases in leaf-S status from maximum application rates of ammonium sulphate and gypsum suggested that ammonium sulphate was the more effective Sfertilizer source. The results confirm that S deficiency is starting to appear in cereal crops in England and Wales.