Phosphorus availability and fractionation vary among forest site types in reconstructed oil sands soils.

We investigated relationships between phosphorus (P) availability and fractionation and growth of lodgepole pine ( Pinus contorta var. latifolia Engelm. ex S. Watson) and white spruce ( Picea glauca (Moench) Voss) in the Athabasca oil sands region. The study sites had peat - mineral soil mix (PMM) as cover soil over a tailings sand substrate planted to pine or an overburden substrate planted to spruce. Available P was determined using a modified Kelowna extraction and sequentially extracted to obtain exchangeable, Fe- and Al-bound, Ca- and Mg-bound, organic, and residual P. The organic P content in PMM explained 83% and 65% of the variations in available P in the pine and spruce sites, respectively. Phosphorus bound to Fe and Al in PMM was also positively related to available P on pine sites ( p < 0.001) but not on spruce sites. Available P in PMM was correlated with aboveground biomass increment of spruce ( p < 0.05) and explained 78% of the variation in foliar P. Foliar P in both pine and spruce was lower than the adequate level for tree growth. Low foliar P and available P in PMM affect the successful establishment of pine and spruce trees on the reclaimed sites, and proper P nutrition management is important to overcome P limitation in reclaimed soils. [ABSTRACT FROM AUTHOR]