Especially in semiarid regions and for calcareous soils there is a need for better understanding of the processes involved in P cycling in soils and the development of better P fertility management to mobilize the recalcitrant P pools for crop uptake. The objective of the present study was to understand the effect of landscape, slope, soil depth and land use on P-availability in Calcareous and Sandy Plain (CP and SP, respectively) landscapes of the central Argentinean Pampas. Soil profiles were described in pits dug at top, mid and footslope positions: soils were classified according to Soil Taxonomy, and samples were taken at fixed depth (0-20, 20-40, 40-60 cm) for each slope position in agricultural soil (AG) and soil under natural vegetation (NV) for physicochemical analyses and the Hedley P-fractionation. The main differences among the landscapes were in calcium carbonate, pH, CEC, exchangeable Ca, and Ca:FeAl ratio. The largest P-fraction was HCl-P in both landscapes and in general, organic P represented about 20% of total P. The most available P-forms were higher in SP. In CP, Anion exchange membrane-P (AEM-P) was defined by organic carbon and exchangeable Ca, while this was not the case for SP. In CP, AEM-P was positively correlated to NaOH-Pi and Po and NaHCO3-Pi and Po, whereas in SP, AEM-P was positively affected by HCl-P and NaHCO3-Pi. AEM-P and NaHCO3-Pi and Po increased towards the footslope position for both CP and SP mainly at 0-20 cm, while deeper strata showed less differences. Also, NV land use showed a higher proportion of available P fractions while AG presented greater differences between slope positions than NV. The knowledge about soil characteristics, the distribution of soil P-fractions and their interaction affecting the P availability facilitates more efficient fertility management, unique to each landscape and position.