Ash results from the processing of corn (Zea mays L.) stover for ethanol production and subsequent combustion to produce electricity. However, the potential value of this ash as a soil amendment has not been fully evaluated. Preliminary chemical analyses of the ash obtained for this study showed potential to raise soil pH and supply K and S. This potential was evaluated at two Iowa fields comparing ash with KCl fertilizer, gypsum, and CaCO₃. Three 2-yr separate K, S, and lime trials were established at each site, where several rates of each material were applied only the first year. Corn was planted in 2014 and soybean [Glycine max (L.) Merr.] in 2015. Soil samples (15-cm depth) were taken at the V6 growth stage of each crop and after crop harvest for analyses of pH, soil-test K, and extractable SO₄^–2. Leaf samples were taken at the corn R1 growth stage and soybean R3 growth stage for analyses of total K and S. There were large K effects on grain yield, soil-test K, and leaf K concentration but no differences between the K sources. First-year soil SO₄^–2 at the V6 corn growth stage and leaf S at the corn R1 stage showed that S supplied by the ash was less than for gypsum, but other measurements were inconclusive as of differences between the S sources. The ash had liming value comparable to pure CaCO₃.