Comparative Investigation of Sequentially Extracted Phosphorus Fractions in a Sandy Loam Soil and a Swine Manure

Sequential fractionation is one of the most common methods used to investigate phosphorus (P) forms in soils. The strategy can be used for evaluating bioavailability of soil P and for investigating the relationship between soil P transformation and soil development. Recently, the strategy of sequential fractionation has been used to investigate manure and compost P and their changes after application to soils. However, the physico-chemical characteristics of animal manure may differ from those of soils. Evaluation is therefore needed to determine if sequentially extracted P forms based on soil studies are applicable for manure. In this study we fractionated P in a sandy loam soil and a swine (Sus scrofa) manure with H2O, 0.5 M NaHCO3, 0.1 M NaOH, and 1.0 M HCl. The P distribution in soil was 0.2% H2O-extractable, 11% NaHCO3-extractable, 58% NaOH-extractable, 14% HCl-extractable, and 16% residual P. In contrast, P distribution in swine manure was 48% H2O-extractable, 19% NaHCO3-extractable, 18% NaOH-extrac...