About Us | Help Videos | Contact Us | Subscriptions

Journal of Environmental Quality Abstract - Waste Management

Phosphorus Distribution in Dairy Manures


This article in JEQ

  1. Vol. 33 No. 4, p. 1528-1534
    Received: Oct 1, 2003

    * Corresponding author(s): zhe@maine.edu
Request Permissions

  1. Zhongqi He *,
  2. Timothy S. Griffin and
  3. C. Wayne Honeycutt
  1. USDA-ARS, New England Plant, Soil, and Water Laboratory, University of Maine, Orono, ME 04469


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 (Pi) accounting for 12 to 44% of manure total P (1400–6800 mg kg−1) and organic phosphorus (Po) for 2 to 23% (130–1660 mg kg−1), respectively. In the NaHCO3 fraction, Pi varied between 740 and 4200 mg P kg−1 DM (4–44% of total manure P), and Po varied between 340 and 1550 mg P kg−1 DM (2–27% of total manure P). In the NaOH fraction, Pi fluctuated around 200 mg P kg−1 DM, and Po ranged from 130 to 630 mg P kg−1 DM. Of the enzymatically hydrolyzable Po 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, H2O-extracted Pi was correlated with total manure P (R 2 = 0.62), and so was NaOH-extracted Po (R 2 = 0.81). Data also show that the amount of P released by a single extraction with sodium acetate (100 mM, pH 5.0) was equivalent to the sum of P in all three fractions (H2O-, NaHCO3–, 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.

  Please view the pdf by using the Full Text (PDF) link under 'View' to the left.

Copyright © 2004. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyASA, CSSA, SSSA