『Abstract
　The objective of this study as to determine how common soil P extractants compared when assessed on revegetated bauxite residue. Samples from contrasting residue preparation, amended with gypsum and/or organic matter, were analyzed for phosphorus using CaCl2, Morgans, Olsen and Colwell extractants. Herbage samples were also taken from the residue and phosphorus content and biomass determined. Phosphorus adsorption in the different treatments was also assessed.
　Amounts determined by CaCl2 were below limits of detection and Morgans extractant overestimated amounts of plant available P. P levels determined by Olsen extractant were within the deficiency range. Colwell P, although overestimated plant available P, did correlate with vegetation performance (biomass production) and amount of P added to the substrate. Plant indices (P-content and biomass) were correlated with organic and Ca content of the substrate.
　Fine particle size of the substrate resulted in increased rate of P adsorption and Ca-content further increased the rate. However, overall Ca content of the residue improved P-uptake and nutrition.

Keywords: Bauxite residue; Plant available phosphorus; Soil phosphorus extraction; Revegetation』

1. Introduction
2. Materials and methods
　2.1. Site selection
　2.2. Soil analysis
　2.3. Herbage analysis
　2.4. Statistical analysis
3. Results
4. Discussion
　4.1. Residue composition
　4.2. Soil phosphorus extractants
　4.3. Plant phosphorus
　4.4. P adsorption
5. Conclusion
Acknowledgements
References

※植物が利用できるリンの分析法は、Peech and English（1944）【Morgan法】とOlsen et al.（1954）【Olsen法】とColwell（1963）【Colwell法】とHouba et al.（1990）【塩化カルシウム法】の4通りが用いられている。