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

Publication date: November 2015
Source:Geoderma, Volumes 257–258
Author(s): Courtney D. Giles , Barbara J. Cade-Menun , Corey W. Liu , Jane E. Hill
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, 10–15cm) during 10weeks 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, 9mgkg⁻¹) in the soil profile. In week 4, orthophosphate (orthoP) represented a greater proportion of total P in the 0–5cm depth (80% or 11mg/kg NaOH–EDTA P) than the 10–15cm depth (72%, 571mg/kg). In contrast, monoester-(17%, 150mgkg⁻¹) and diester-P classes (10%, 60mgkg⁻¹) were most abundant in the 10–15cm depth. In week 4, the ³¹P NMR spectrum of the 0–5cm 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 (<10week) 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.

Graphical abstract