Sulfuric acid and ferrous sulfate treatnients of calcareous soil increased yields of hybrid grain sorghum grown in the greenhouse. Effects of 250 ppm or more Fe with 250 ppm or more H2SO4 were still significant on the third crop after soil treatments were made. This study shows that residual effects are possible from heavy applications of FeSO4and H2SO4.In a field experiment, 560 kg/ha iron as FeSO4 or 560 kg/ha of H2SO4 produced about the same yield response on calcareous Arch Fine sandy loam.