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Phosphorus Distribution in Dairy Manures
Author(s) -
He Zhongqi,
Griffin Timothy S.,
Honeycutt C. Wayne
Publication year - 2004
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/jeq2004.1528
Subject(s) - manure , chemistry , zoology , phosphorus , fractionation , bioavailability , dry matter , manure management , organic matter , hydrolysis , agronomy , biochemistry , chromatography , biology , organic chemistry , bioinformatics
The chemical composition of manure P is a key factor determining its potential bioavailability and susceptibility to runoff. The distribution of P forms in 13 dairy manures was investigated with sequential fractionation coupled with orthophosphate‐releasing enzymatic hydrolysis. Among the 13 dairy manures, manure total P varied between 4100 and 18300 mg kg −1 dry matter (DM). Water‐extractable P was the largest fraction, with inorganic phosphorus (P i ) accounting for 12 to 44% of manure total P (1400–6800 mg kg −1 ) and organic phosphorus (P o ) for 2 to 23% (130–1660 mg kg −1 ), respectively. In the NaHCO 3 fraction, P i varied between 740 and 4200 mg P kg −1 DM (4–44% of total manure P), and P o varied between 340 and 1550 mg P kg −1 DM (2–27% of total manure P). In the NaOH fraction, P i fluctuated around 200 mg P kg −1 DM, and P o ranged from 130 to 630 mg P kg −1 DM. Of the enzymatically hydrolyzable P o in the three fractions, phytate‐like P dominated, measuring 26 to 605 mg kg −1 DM, whereas monoester P and DNA‐like P were relatively low and less variable. Although concentrations of various P forms varied considerably, significant correlations between manure total P and certain P forms were observed. For example, H 2 O‐extracted P i was correlated with total manure P ( R 2 = 0.62), and so was NaOH‐extracted P o ( R 2 = 0.81). Data also show that the amount of P released by a single extraction with sodium acetate (100 m M , pH 5.0) was equivalent to the sum of P in all three fractions (H 2 O‐, NaHCO 3 –, and NaOH‐extractable P). Thus, a single extraction by sodium acetate buffer could provide an efficient evaluation of plant‐available P in animal manure, while the sequential fractionation approach provides more detailed characterization of manure P.