The results confirm our hypotheses, namely, after re-flooding of sulfuric material: (i) pH increase or organic matter addition alone has little effect on sulfate reduction, (ii) only the combined treatment (+C + pH) induces a significant increase in sulfate reduction compared to the control, and (iii) the increase in sulfate reduction by this treatment is related to soil properties such as soil texture and the presence of competing electron acceptors such as nitrate.