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United States Department of Agriculture

Agricultural Research Service

Research Project: NUTRIENT CYCLING AND UTILIZATION ON ORGANIC DAIRY FARMS

Location: New England Plant, Soil and Water Research Laboratory

Title: Sequentially-Extracted Phosphorus from Poultry Litter and Soil: Enzymatic and 31P NMR Characterization

Authors
item He, Zhongqi
item Honeycutt, Charles
item Cade-Menun, Barbara - STANFORD UNIVERSITY
item Senwo, Zachary - ALABAMA A&M UNIV
item Tazisong, Irenus - ALABAMA A&M UNIV

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 12, 2008
Publication Date: September 1, 2008
Citation: He, Z., Honeycutt, C.W., Cade-Menun, B.J., Senwo, Z.N., Tazisong, I.A. 2008. Sequentially-Extracted Phosphorus from Poultry Litter and Soil: Enzymatic and 31P NMR Characterization. Soil Science Society of America Journal. 72:1425-1433.

Interpretive Summary: Knowledge of the phosphorus (P) forms in poultry litter (PL) and their transformations in soil will help improve our understanding of the long-term role of P in water quality. For this reason, efforts have been made to obtain more detailed information on P forms in soil and manure. In this study, samples of PL and pasture soils with and without 20 years of PL application were investigated to determine the different forms of P present. Compared to soil not receiving PL, 20-year application of PL increased the pools of both labile and stable inorganic P in soil. However, repeated application of PL did not lead to a significant build-up of hydrolyzable organic P in stable fractions, indicating that the stable organic P in PL must have been degraded in soil to other forms. The degradation of the stable PL organic P observed in this study could be an important mechanism for maintaining a balance between labile and immobile P in soils.

Technical Abstract: Knowledge of the phosphorus (P) forms in poultry litter (PL)and their transformations in soil will help improve our understanding of the long-term role of P in eutrophication. In this study, samples of PL and pasture soil with and without 20 years of PL application, were sequentially extracted to separate P into H2O, 0.5 M NaHCO3, 0.1 M NaOH, and 1 M HCl fractions. After appropriate dilution and adjustment to pH 5.0, the fractions were incubated in the presence of orthophosphate-releasing enzymes. The peaks of Po species became very weak or disappeared in the solution 31P NMR spectra of the enzymatically-treated fractions, which confirmed the validity of P identities in the untreated fractions detected by enzymatic hydrolysis or solution 31P NMR spectroscopy. Thus, we conclude that both methods can be used to characterize P in an environmental sample. Although the majority of P in NaOH and HCl fractions of PL was in organic forms, these stable organic P forms could be subjected to enzymatic hydrolysis after being applied to soil, which was indeed supported by the soil P data. Compared to non-litter applied soil, 20 years of PL application increased the pools of both labile and stable inorganic P in the soil. However, repeated application of PL did not lead to significant accumulation of hydrolyzable organic P in NaOH and HCl fractions, indicating that the stable (hydroxide and acid extractable) organic P must have been converted to other forms. The transformation of stable PL organic P observed in this study could be an important mechanism for maintaining a balance between labile and immobile P in soils.

Last Modified: 7/28/2014
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