Short term S availability markedly depends on C/S ratio (r2=0.95), and to a less degree on SO42- content (r2=0.50) of organic fertilisers. In pot experiments highest mineral fertiliser equivalents of 77 and up to 59% were obtained with urine (C/S 11) and sewage sludge (C/S 11–28) followed by slurry (C/S 81), stable manure (C/S 84) and biocompost (C/S 70) with equivalents of 17, 13, and 8%. Long term S effect is related to an increased S release potential in soil and in consequence a higher net S mineralisation.