Manganese deficiency has been implicated as an important factor in the susceptibility of crop plants to some soil-borne pathogenic fungi, but the factors influencing plant-available soil Mn are very poorly understood. We conducted a 2-year study to evaluate the effects of crop rotation and tillage on available soil Mn at the Agronomy Center for Research and Education (ACRE) in West Lafayette, Indiana. Samples were taken from plots under continuous corn [Zea mays (L.)], continuous soybean [Glycine max (L.)], and corn-soybean-wheat [Triticum aestivum (L.)] rotations under no-till tillage and fall chisel tillage systems at 1-month intervals during the growing season. Mn was extracted using a 3-step sequential extraction using 1M NH₄OAc at pH 7, 1M NH₄OAc at pH 3, and 0.018M quinol in 1M NH₄OAc at pH 7. Extracts were analyzed using atomic adsorption spectroscopy. Crop rotation had significant effects on Mn extracted with 1M NH₄OAc at pH 7, with the continuous corn showing the highest extractible Mn with a back-transformed Least Squares Mean (LSM) of 13.1 mg Mn kg^-1 soil for 2002, and 15.7 mg kg^-1 for 2003. Continuous corn had more extractible Mn than all other treatments in both years. Continuous soybean had the lowest extractible Mn, with 4.5 mg kg^-1 in 2002 and 7.5 mg kg^-1 in 2003. Soybean, wheat, and corn in rotation were not significantly different in either year. Soybean in rotation was significantly different from continuous soybean in 2003, but not in 2002. Wheat in rotation was not significantly different from continuous soybean in either year. Corn in rotation was significantly higher than continuous soybean in 2002 but not in 2003. Tillage did not significantly change extractable Mn in either 2002 or 2003. The crop, therefore, can significantly alter the plant available Mn of the soil in which it is grown.