Laboratory Procedures for Characterizing Manure Phosphorus

Abstract

Phosphorus runoff from agricultural land contributes to accelerated eutrophication of surface waters. In areas with intensive animal farming, P loss from manured fields may be elevated due to high concentrations of soluble P in manure. We characterized P in dairy and poultry manure for the relative dissolution and fraction distribution using deionized water (H2O), 0.5 M NaHCO3, 0.1 M NaOH, 1.0 M HCl, and 5% trichloroacetic acid (TCA). Two extraction procedures were tested: (i) independent, with dried, ground samples being extracted repeatedly and P measured for each extractant; and (ii) sequential, with each sample being repeatedly extracted by H2O, NaHCO3, NaOH, and HCl, in that order. For the independent procedure, H2O extracted 53 to 64%, NaHCO3 64 to 72%, NaOH 33 to 54%, HCl 90 to 97%, and TCA 84 to 96% of the total P in manure. Sequentially, H2O, NaHCO3, NaOH, and HCl extracted 70, 14, 6, and 5% of the total P in the dairy, and 49, 19, 5, and 25% of the total P in the poultry sample, respectively. Manure P release was not greatly affected by shaking time but decreased rapidly with increasing number of repeated extractions. A large portion of P in manure being extractable by H2O or NaHCO3 suggests weak binding energy of P and hence a high susceptibility for loss to waters when conditions favor runoff. A 1‐h shaking of manure with H2O may provide a quick measure of the relative magnitude of P that is most susceptible. Further investigation relating manure P fractions with P in runoff would help identify management alternatives for reduced P losses.

Phosphorus Compounds in Sequential Extracts of Animal Manures: Chemical Speciation and a Novel Fractionation Procedure

“…However, this is likely to influence phosphorus solubility. For example, Sharpley and Moyer (17) reported that most of the phosphate in a range of fresh manures stored at 4 °C was recovered in the NaOH fraction, whereas Dou and colleagues (18) recovered most of the phosphate from a dairy manure dried at 65 °C in the initial water extract, although this was performed exhaustively. Leinweber and colleagues (16) freeze-dried a liquid swine manure and a chicken manure prior to sequential fractionation but recovered only 60% of the phosphorus.…”

Soil phosphorus fractions in sandy soils amended with cattle manure for long periods

“…Dou et al (2000) found that approximately 70 % of the P in cattle manure was water-extractable, but this type of information is not available for the FYM used in the semi-arid region of Brazil. There is no information either on the transformations of this P source after several years of FYM application to the soil.…”

Accelerated phosphorus accumulation and acidification of soils under plastic greenhouse condition in four representative organic vegetable cultivation sites

“…Phosphorus (P) is not only an important 4 plant nutrient, but also a major contaminant in the water environment. However, information on the 5 accumulation and distribution of P in organic vegetable soils under plastic greenhouse conditions is 6 limited, relative to the open cultivation systems. Therefore, twenty-six plastic greenhouse vegetable PGVS with similar soil and cultivation practices were selected.…”