Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2010
Publication Date: 4/15/2010
Citation: He, Z., Zhang, H., Toor, G.S., Dou, Z., Honeycutt, C.W., Haggard, B.E., Reiter, M.S. 2010. Phosphorus Forms in Sequentially-Extracted Fractions of Biosolids and Broiler Litter. Soil Science. 175:154-161. Interpretive Summary: Phosphorus is an essential nutrient for plant growth. Land application of biosolids (municipal wastes) and poultry litter can benefit crop production by providing phosphorus and other nutrients. However, the plant availability of phosphorus in waste materials depends on the presence of specific phosphorus forms. In this study, we examined the different forms of phosphorus in biosolids and broiler litter. Both contained significant amounts of phosphorus, but it was distributed in different pools with different plant-availabilities. Poultry litter contained more soluble (plant-available) phosphorus, but the majority of phosphorus in biosolids was only extractable with strong base and acid solutions. Results from this study add to our knowledge of phosphorus characteristics in biosolids and broiler litter and can help improve our understanding of phosphorus availability to plants from these sources.
Technical Abstract: Phosphorus (P) is an essential nutrient for plant growth. Land application of biosolids and poultry litter can benefit crop production by providing P and other nutrients. However, the bioavailability of applied P in waste materials is directly dependent upon the presence of specific P forms. In this study, we comparatively examined the P forms in biosolids and broiler litter by sequential fractionation coupled with enzymatic hydrolysis. First, P in the waste materials was partitioned into four sequential fractions (H2O, 0.5 M NaHCO3, 0.1 M NaOH, and 1 M HCl). Biosolid P was found in the four fractions in the following order: H2O<NaHCO3<NaOH<HCl. Extractable P in broiler litter was found in the order of NaHCO3<NaOH<H2O<HCl. The relative abundance of P was determined to be: inorganic P>hydrolyzable organic P>nonhydrolyzable organic P in each fraction. We also observed significant amounts of organic P in the HCl fractions of both biosolids and broiler litter. This suggests that both inorganic and organic P should be experimentally determined in the sequentially-extracted HCl fraction. As most studies have ignored the presence of organic P in HCl-extracts, this addition will provide a more sound approach for investigating the fate and transformations of P in soils amended with biosolids and poultry litter.