The short-term transport and transformation of phosphorus species in a saturated soil following poultry manure amendment and leaching

The application of manures for fertilization will influence the composition of phosphorus (P) species in the soil profile and the extent of dissolved P leaching to surface waters. Spatial and temporal changes in the P species composition of poultry-manure-amended soil were assessed at two soil column depths (0–5, 10–15 cm) during 10 weeks of leaching. Leachate P was primarily composed of dissolved fractions (soluble reactive P; dissolved unreactive P) and reached a maximum in the fourth week of leaching, concurrent with maxima in the degree of P saturation (DPS; 80%) and water extractable P (WEP, 9 mg kg− 1) in the soil profile. In week 4, orthophosphate (orthoP) represented a greater proportion of total P in the 0–5 cm depth (80% or 11 mg/kg NaOH–EDTA P) than the 10–15 cm depth (72%, 571 mg/kg). In contrast, monoester-(17%, 150 mg kg− 1) and diester-P classes (10%, 60 mg kg− 1) were most abundant in the 10–15 cm depth. In week 4, the 31P NMR spectrum of the 0–5 cm depth soil was most similar to that of the poultry manure, which may have contributed to the mobility of P species, including orthoP, myo-inositol hexakisphosphate (phytate or myo-IHP), and nucleic acids. The appearance of neo- and D-chiro-IHP, as well as phospholipid signals during the leaching period indicate possible short-term (< 10 week) contributions of organic P to the generation and leaching of orthoP, specifically under P-saturated conditions. This work reaffirms current best management practices to consider soil DPS prior to manure amendment in order to minimize the generation of excess inorganic P and loss of dissolved P species to receiving waters.