A greenhouse leaching column study was conducted to compare the effects of surface‐applied langbeinite (LB), phosphogypsum (PG), Ca‐ silicate slag (SS), and calcitic lime (CL) on subsoil Al and growth of alfalfa (Medicago sativaL. ‘Florida 77') in Toula silt loam soil (Typic Fragiudult). Langbeinite was foundtobe more effective than PG in the reduction of subsoil exchangeable Al, apparently through SO42‐‐induced Al precipitation. This study demonstrated that high exchangeable Al levels are not always indicative of Al toxicity in the soil solution phase. The primary factors limiting alfalfa growth in the Toula soil were found to be surface soil pH and Mn toxicity rather than subsoil Al toxicity. The liming materials, SS and CL, effectively corrected the surface soil Mn and pH problems, but had no effect on subsoil chemical properties.