The effects of rate and pattern of fertilizer S application on herbage production from Perennial ryegrass‐dominant swards at six potentially S‐deficient sites in south‐west Scotland were measured under a silage cutting regime (3 cuts year‐1) with high fertilizer N application (300 kg ha−1 year‐1). Fertilizer S (as gypsum) was applied at annual rates from 0 to 48 kg ha−1 as single spring applications before the first cut or split before each of the three cuts. The residual effect of S in the year following its application was assessed at one site. Applied S increased total DM production at four of the six sites. These increases were restricted to the second and/or third cuts and were generally in the range 10‐30% greater than where no S was applied. Timing of S application was not important in influencing annual DM yield. The residual effect of gypsum in the year following application was small. The supply of available soil S is limiting herbage production in certain areas and soil types of south‐west Scotland. Areas of S deficiency are likely to increase in the future and need to be identified more precisely than they are at present.

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