Cross,A.F. and Schlesinger,W.H.(1995): A literature review and evaluation of the Hedley fractionation: Applications to the biogeochemical cycle of soil phosphorus in natural ecosystems. Geoderma, 64, 197-214.

『ヘドレイ分画法の文献レビューおよび評価：天然生態系における土壌リンの生物地球化学循環への適用』

『Abstract
　The Headley fractionation recognizes plant-available forms (Resin Pi, Bicarb Pi, and Bicarb Po) and refractory forms (NaOH Pi, NaOH Po, Sonic Pi, Sonic Po, HCl Pi, Residual P) of soil phosphorus. This updated survey of the recent literature shows that the sequential fractionation proposed by Hedley et al. can also be used to separate forms of organically bound soil phosphorus from the geochemically bound fractions. We consider that biological P includes all the extracted organic fractions (Bicarb Po, NaOH Po, Sonic Po) and geochemical P includes the remaining fractions (Resin Pi, Bicarb Pi, NaOH Pi, Sonic Pi, HCl Pi) and the Po and Pi in the Residual fraction.
　Data from the Hedley fractionation suggest that the contribution of geochemical versus biological processes to soil phosphorus availability varies with pedogenesis. The pool of primary phosphate declines and the NaOH and sonicated-NaOH phosphorus fractions increase as phosphorus becomes geochemically fixed to the iron and aluminum oxides in more highly weathered soils. The sum of organic-P fractions - biological P - is an increasing proportion of total available P as a function of soil development. Therefore, the Hedley fractionation provides a valuable index of the relative importance of biological processes to soil phosphorus content across a soil weathering gradient.』

1. Introduction
2. Literature survey
3. Methods
4. Results
5. Discussion
Acknowledgements
References

図1　土壌に対するHedley連続リン分画法（Tiessen et al.,1984から）（元は図）
50 mLの遠心分離管に0.5ｇの土壌試料 30 mLの脱イオン水と0.4 gのDowex（ダウエックス、イオン交換樹脂）1×8-50の炭酸水素塩（重炭酸塩）態の陰イオン交換樹脂を加え、16時間振とう、樹脂バッグ除去、遠心分離、上澄み液廃棄 樹脂P（Pi）
土壌 30 mLのNaHCO3（炭酸水素ナトリウム）（pH 8.5）を加え、16時間振とう、遠心分離、上澄み液採取 Bicarbonate P（炭酸水素塩P）（PiとPo）
土壌 30 mLの0.1M NaOH（水酸化ナトリウム、苛性ソーダ）を加え、16時間振とう、遠心分離、上澄み液採取 Hydroxide P（水酸化物P）（PiとPo）
20 mLの0.1M NaOHを加え、2分間氷浴中で75W（Braunsonic 1510）で超音波処理、30 mLに容積調整、16時間振とう、遠心分離、上澄み液採取 Sonicate/hydroxide P（超音波処理／水酸化物P）（PiとPo）
土壌 30 mLの1.0M HCｌ（塩酸）を加え、16時間振とう、遠心分離、上澄み液採取 Acid P（酸P）（Pi）
残渣土壌 5 mLのH2SO4（硫酸）とH2O2（過酸化水素）で温浸（Digest） Residue P（残渣P）（全Pのみ）

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