Phosphorus fertilizer-use efficiency is a limiting factor for economic crop production. To evaluate the long-term effects of variable tillage systems on P adsorption and desorption by soils, composite samples (fine, illitic, active, mesic, mollic, Epiaqualfs) at 0-7.5 and 7.5-15 cm depth were randomly collected from 2, 20, and 40 yr NT and their adjoining conventionally tilled (CT) fields in Wood County, northern Ohio. Soil samples were processed and analyzed for P adsorption characteristics. The P adsorption capacity (Kf), adsorption intensity (1/n), adsorption maxima (b), bonding energy (k), buffering capacity (bk), and desorption were determined by using logarithmic regression of the data obtained from the Freundlich and Langmuir adsorption isotherms. Results showed that P adsorption increased while percent P adsorption decreased gradually with increasing P levels. However, P adsorption changed significantly in response to tillage operations. Soil P adsorption maxima and the extent of adsorption were significantly lower in response to long-term NT operations. Furthermore, P desorption was higher in NT soils than CT soils. Results suggest that NT may have beneficial effects to decrease buffering capacity and increase P availability in soil.