Agricultural practices affect soil P status, which is the key factor affecting P bio-availability and susceptibility to loss. Previous studies mostly focused on short-term effects and were limited to assessments within agricultural ecosystems. We evaluated the effects of consistent long-term (43 years) cropping (Continuous Corn: CC, Continuous Bluegrass: CB, and Crop Rotation of corn-oats-alfalfa-alfalfa: CR) with and without fertilization on changes in soil P as compared to that in a natural (virgin) forest ecosystem for a Brookston clay loam soil. Soil P was fractionated into various inorganic (Pi) and organic P (Po) forms. Soil P loss was determined by analysing tile drainage water samples, which were year-round continuously collected from the entire large filed plots using an automated sampling system. Under virgin forest, soil P was predominated by stable P, followed by moderately stable Pi (HCl-Pi) and moderately labile Po (NaOH-Po). Consistent cropping without fertilization reduced all forms of soil P relative to virgin forest; i.e. labile P (NaHCO3-P) and moderately labile P were reduced by 60-76% and moderately stable and stable P were reduced by 30-39%. Consistent cropping with fertilization reduced all forms of Po, in the order of CC>CR>CB, but increased labile and moderately Pi in the order of CB>CC>CR. Moderately stable Pi increased with fertilization in CC and decreased in RC and CB. All forms of soil P are in a dynamic system, of which the transformation pathways may depend on the balance of soil P input vs. output. Cultivation of virgin soil causes losses of soil Po, which may not be remedied by fertilization. Unfertilized CC and CB had similar flow-weighted mean P concentrations of 0.043, 0.035 and 0.19 mg P L-1 for Dissolved Inorganic P (DIP), Dissolved Organic P (DOP) and Particulate P (PP), respectively, while the corresponding concentrations under unfertilized RC were greater by 6 %, 25 % and 14 % , respectively. Fertilization increased flow-weighted means of DIP, DOP and PP in tile water by an average of 375 %, 393 % and 75 %, respectively, relative to no fertilization. Either with or without fertilizations, flow-weighted mean DIP and DOP followed the order CB>RC>CC, while the reverse order occurred for PP. The total annual soil P losses in tile water were 226-1253 g P ha-1 for the unfertilized treatments, and 96-611 % greater for the fertilized treatments. Total annual P loss and total tile discharge volume followed the order CB>RC>CC regardless of fertilization. The leaching of soil P into tile drainage can consequently be substantial, and strongly influenced by cropping system.