Abstract
Sequential fractionation coupled with phosphatase hydrolysis allows a greater understanding of the effects of animal manure on the chemical distribution of soil P. Concentrations of specific soil P fractions were determined after long-term (>10 yr) poultry litter application at rates of 4.5, 6.7, 9.0, 11.2, and 13.4 Mg manure ha-1 yr-1 to watershed-scale plots (cultivated and grazed-ungrazed pasture) on a calcareous Texas Blackland Vertisol. Soil total extractable P (Pt) and inorganic P (Pi) were quantified following sequential extraction with H2O, NaHCO3, NaOH, and HCl. Hydrolyzable organic P (Pe) and non-hydrolyzable organic P (Pne) were determined in the extracted fractions following enzymatic hydrolysis. Litter application increased Pt regardless of land-use type compared with the control. Concentrations of H2O-extractable Pi in litter-amended plots increased by 9 to 34% (cultivated) and 7 to 30% (pasture) over the control, indicating substantial risk of soluble P runoff. Labile organic P (P0) extracted with H2O and NaHCO3 decreased in the order monoester > nucleic acid > phytate > Pne. An average of 68% of Pt was extractable with HCl. Organic P comprised the majority (95%) of HCI-Pt; however, only trace levels of HCI-P0 were hydrolyzable, and litter application increased HCI-Pne up to 217%. Thus, litter application increased levels of both soluble Pj and stable Pne, but the specific response varied with application rate and land management. This study increased understanding of P chemical distribution with time in litter-amended soil with high clay and CaCO3 contents under differing land-use scenarios.
Original language | English (US) |
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Pages (from-to) | 1601-1614 |
Number of pages | 14 |
Journal | Soil Science Society of America Journal |
Volume | 79 |
Issue number | 6 |
DOIs | |
State | Published - Nov 1 2015 |
Bibliographical note
Publisher Copyright:© Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA. All Rights reserved.
Keywords
- Abbreviations: DPS
- Degree of phosphorus saturation
- NMR
- Nuclear magnetic resonance
- OM
- Organic matter
- STP
- Soil test phosphorus