Ranatunga,T.D., Reddy,S.S. and Taylor,R.W.(2013): Phosphorus distribution in soil aggregate size fractions in a poultry litter applied soil and potential environmental impacts. Geoderma, 192, 446-452.

『家禽廃物含有土壌における土壌塊サイズ留分中のリン分布と起こりうる環境影響』

『Abstract
　Long-term poultry litter (PL) application in pasture soil was found to enhance accumulation of certain phosphorus (P) forms in soil micro-aggregate fractions and have potential impacts on non-point water pollution by wind erosion of run-off. A P fractionation method was utilized to identify P forms in aggregate fractions derived from a long-term PL applied pasture soil. Enrichment of surface soil P by PL application has considerable effects on increasing specifically the labile P forms in surface soil micro-aggregates. Particular concern is of accumulation of water soluble and labile inorganic P forms in micro-aggregate particles susceptible to wind and soil erosion. Continuous application of PL to pasture fields for at least 15 years at a rate of 2.3 T ha-1 y-1 resulted in considerable increase in inorganic P forms including Mehlich-3, water soluble and labile bicarbonate P (NaHCO3-P forms in most aggregate size fractions. Mehlich-3-P was highest in ＜0.053 mm micro-aggregates (223.8 mg kg-1) and relatively high amounts ranging from 145.5 to 170.4 mg kg-1 were found in 0.053-1.0 mm micro-aggregates. High levels of water soluble P were found in majority of micro-aggregates particles in PL supplied soil, which amounts to 11-18％ of total inorganic P in these particles. Bicarbonate-P or labile inorganic P forms were at elevated levels in 0.125-0.25, 0.053-0.125 and ＜0.053 mm micro-aggregates, which amounts to approximately 11-22％ of total inorganic P in these particles. The PL application also increased the NaOH extractable P (NaOH-P) or Al/Fe bound P in soil aggregate fractions (192-347 mg kg-1). Notable increase in labile organic P forms in certain micro-aggregate size fractions may be of concern due to ease of P mineralization.

Keywords: Soil aggregate fractions; Poultry litter; Phosphorus forms; Environmental impacts; Pasture sandy soil; Dithionite』

1. Introduction
2. Materials and methods
　2.1. Study site
　2.2. Soil sampling
　2.3. Characterization of soils
　2.4. Soil aggregate fractionation
　2.5. Chemical analysis
　2.6. Statistical analysis
3. Results and discussion
　3.1. Soil aggregate size fractions
　3.2. Phosphorus distribution in aggregate fractions
　　3.2.1. Available P (Mehlich-3 phosphorus)
　　3.2.2. Sodium dithionite/citrate extractable Fe, Al, and occluded P forms
　　3.2.3. Phosphorus forms in soil aggregate size fractions
4. Conclusion
Acknowledgments
References

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