ABSTRACTThe importance of subsurface phosphorus (P) transport in deterioration of surface water quality is welldocumented. Practices and treatments have been identified and modeling approaches have been implemented todecrease the subsurface P load to surface waters. Soil phosphorus storage capacity (SPSC) is a site-assessmenttool that predicts the potential for P loss from soils. We examined the use of SPSC to assess soil profile Pdistributions and loss potentials for two contrasting soil types: manure-impacted Spodosols and Ultisols. Ourspecific objectives were to (i) validate prediction of the Langmuir P bonding strength, KL, the Freundlichadsorption coefficient, KF, or the linear adsorption coefficient, KD, of Spodosols (Ap, E and Bh horizons) andUltisols (Ap, E and Bt horizons) using SPSC-based equations developed for surface and sub-surface horizons (Ap,E and Bt) of Ultisols and (ii) identify factors affecting retention and release of P. Results showed that SPSCderived from oxalate-extractions data can effectively predict P isotherm parameters used in P transport models.The SPSC also captured differences between soil horizons within a profile pertinent to P loss. Magnesium (Mg)and calcium (Ca) concentrations related to negative SPSC, likely due to the presence of these components indairy manure. The initial sorbed P in the solid phase (S0) of both soil types was related to soil components suchas Mg, Ca and total P when SPSC was positive. The equations developed from A, E and Bt horizons of Ultisolrelating isotherm parameters to the PSR and SPSC made successful predictions for all horizons of Ultisolssampled from locations different from those in the current study and Spodosols suggesting that such equationsmight be applicable across a wide range of soils.