Taxonomic and Geographic Distribution of Total Phosphorus in Florida Surface Soils

摘要

Taxonomic and geographic distributions of background P concentrations are important in assessing whether a soil P level is influenced by anthropogenic activities. This study was conducted to establish an upper baseline concentration (UBC) of soil P, which is defined as 97.5% of the background concentration, using 448 geographically and pedogenically representative Florida surface soils (genetic horizon A, A1, Ap, O, O1 or Op) using total P as determined by the USEPA Method 3052 (HCl–HNO₃–HF digestion). A significant difference existed in total P concentrations between disturbed (126 mg kg-1, n = 180) and undisturbed (60 mg kg-1, n = 268) soils. Geometric mean (GM) concentration of total P in the undisturbed soils decreased in the order of Histosols (350 mg kg-1) > Mollisols (171 mg kg-1), Inceptisols (140 mg kg-1) > Ultisols (88 mg kg-1) > Alfisols (54 mg kg-1), Entisols (53 mg kg-1) > Spodosols (24 mg kg-1). Aquic suborders tended to have greater P contents than the dry suborders, e.g., Aquents (92 mg kg-1) > Psamments (47 mg kg-1) and Aquods (27 mg kg-1) 4–fertilizer application and population growth as nonpoint sources.