Phosphorus-related properties in the profiles of three Italian soils after long-term mineral and manure applications

The long-term evolution (44 years) of phosphorus (P) in 1-m profile of three reconstructed soils (0–80 cm = sandy, SDY; clay, CLY; and peaty, PTY; 80–100 cm = native layers) typical of the Po Valley (northern Italy) has been studied in a factorial experiment with farmyard manure and mineral fertilizer. Calcium, magnesium, aluminium, and iron concentrations were determined as total (CaT, MgT) and pseuto-total (AlPT and FePT) amounts and as extractable forms by Mehlich-3 (M3) and ammonium oxalate (Ox) extracting solutions. The P distributions in total P (TP), organic P (Porg), H2SO4 P (image), and the more mobile NH4F P (image) and NaOH P (PNaOH) were also measured.