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Phosphorus Speciation and Sorption‐Desorption Characteristics in Heavily Manured Soils
Author(s) -
Dou Zhengxia,
Ramberg C. F.,
Toth J. D.,
Wang Y.,
Sharpley A. N.,
Boyd S. E.,
Chen C. R.,
Williams D.,
Xu Z. H.
Publication year - 2009
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2007.0416
Subject(s) - soil water , chemistry , sorption , manure , phosphate , environmental chemistry , phosphorus , compost , desorption , zoology , agronomy , adsorption , biology , environmental science , soil science , biochemistry , organic chemistry
Managing heavily manured soils for decreased P loss to waters requires improved understanding of the chemical and sorption–desorption characteristics of P in these soils. We used soils from agricultural fields receiving ≥8 yr of dairy, poultry, swine manure or spent mushroom compost for the determination of P functional groups in NaOH‐EDTA extracts by solution 31 P nuclear magnetic resonance (NMR) spectroscopy, degree of P saturation (DPS), and P sorption–desorption isotherms. The 31 P NMR results show that inorganic orthophosphate was the primary form of P in manure treated (79–93% of total extract P) and untreated soils (33–71%). Pyrophosphate and phosphate monoesters were identified in all soils, whereas phosphate diesters were present in small proportions (<3%) in only a few soils. Polyphosphate, a more condensed form of inorganic P, was present in seven out of nine manured soils (9–47 mg P kg −1 , <2%) but absent in untreated soils. Concentrations of inositol hexakisphosphate (IHP), mostly myo ‐IHP plus some scyllo ‐IHP, were similar in manured soils (52–116 mg P kg −1 , 2–8%) and untreated soils (43–137 mg P kg −1 , 6–22%), suggesting a lack of IHP accumulation despite long‐term manure applications, including poultry manures that are typically rich in IHP. Most of the treated soils had DPS ≈ 80 to 90% compared with 11 to 33% for the untreated samples. Results from P sorption isotherms showed that potential P release was 3 to 30 times greater from treated than untreated soils. The lack of IHP accumulation in soils receiving long‐term manure applications implies that manure‐derived IHP may not be biologically and environmentally benign.