Fig. 5.Changes in pH, redox and sulfate content of sulfuric soil maintained under anaerobic conditions for 6 months with (solid symbols) or without (open symbols) mulch (Phragmites shoots) overlaid at a rate of 1 g per 80 g soil. Initial sulfate content approximately 32 μmol g−1 dry soil. Values are mean ± s.e. (n = 3). Asterisks indicate significant differences (p b 0.05) between treatments at each depth.