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Water‐Extractable Phosphorus in Animal Manure and Manure Compost: Quantities, Characteristics, and Temporal Changes
Author(s) -
Liu Jian,
Spargo John T.,
Kleinman Peter J. A.,
Meinen Robert,
Moore Philip A.,
Beegle Douglas B.
Publication year - 2018
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2017.12.0467
Subject(s) - compost , manure , zoology , broiler , manure management , agronomy , biology
Water‐extractable P (WEP) in manure and manure compost is widely used as an indicator of P release to runoff from manure and compost that are land applied. A survey of 600 manures and composts was conducted to assess trends in WEP (dry weight equivalent) related to manure and compost types from sources in the Mid‐Atlantic region. Manure and compost WEP ranged from 0.2 to 20.8 g kg −1 . Mean WEP was highest in turkey and swine manures (manure: 4.1–5.6 g kg −1 ; no composts tested), followed by layer and broiler chicken manures (manure: 3.0–3.5 g kg −1 ; compost: 4.6–5.1 g kg −1 ), cattle manure (dairy and beef manure: 2.1–2.8 g kg −1 ; compost: 1.1–2.7 g kg −1 ), and horse manure (manure: 2.7 g kg −1 ; compost: 1.9 g kg −1 ). Across all manures and composts, WEP was negatively correlated with manure dry matter content ( r = 0.42, p < 0.001). Moreover, WEP was strongly correlated ( r = 0.66, p < 0.001) to degree of P saturation expressed as a molar ratio of total P to total metals (Ca, Mg, Fe, Al, and Mn). Although WEP levels of beef, broiler chicken, and turkey manures from this survey are similar to those from a decade ago, WEP is now significantly lower for dairy (30%, p < 0.001), swine (46%, p < 0.001), and layer chickens (39%, p < 0.05). Lower WEP resulted from decreasing total P and/or increasing P sorption capacity, combined with increasing dry matter content. Results highlight the potential to use degree of P saturation to predict WEP and suggest an opportunity to reduce WEP by managing manure handling, storage, and chemistry. Core Ideas Water‐extractable P (WEP) and WEP/total P ratio vary widely across animal manures. Total P/total metals in manure and compost can be used to estimate degree of P saturation. WEP is strongly correlated with degree of P saturation in manure and compost. Current manure WEP in the US Northeast is generally lower than a decade ago. The properties of different manures can be used to guide practices to minimize P solubility.