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

Giles, C.D., Cade-Menun, B.J., Liu, C.W., and Hill, J. (2014). "The short-term transport and transformation of phosphorus species in a saturated soil following poultry manure amendment and leaching.", Geoderma, 257-258, pp. 134-141. doi : 10.1016/j.geoderma.2014.08.007  Access to full text

Abstract

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.

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