新鮮火山灰に含まれるアパタイトと土壌-植物系における主な活性成分との短期間における反応性

概要

論文の詳細を見る
The reactivity of the apatite in the volcanic ash from Mt. Pinatubo, Philippines, to various soil components (Al, Fe and organic acids) was examined in this study. The heavy fraction (specific gravity>2.8) of the volcanic ash having the diameter of 0.044-0.2 mm was first separated by sieving in water, and then by centrifugation using heavy liquid. The content of P_2O_5 in the heavy fraction thus obtained was 6.5 g kg^<-1>, One-hundred milligrams of the heavy fraction was shaken with 500 mg of four soils containing different amounts of active Al and Fe, four model materials (Al-gel, Al-Si-gel, Fe-gel and goethite), organic acids (10 mM of citrate and oxalate), and dilute HCl(0-4 mM) in 25 mL of aqueous solution for 16 h. The pH values of the solution ranged from 3 to 7 when the experiments were completed. The amounts of dissolved apatite P increased with the decrease in the final pH of the solutions. For all soil samples, Al-gel, and Al-Si-gel, the amounts of dissolved apatite P became noticeable only when the final pH values were lower than 4.5. On the contrary, the reactivity of active Fe with apatite was higher than that of active Al. Substantial reactions between Fe-gel and goethite and apatite were observed under the final pH ranges of 3-7. The amounts of apatite P reacted with Fe-gel increased with the amount added, suggesting that the amount of active Fe contained in the soil samples examined were not sufficient to react with the apatite. It was suggested that apatite does not react with active Al immediately under normal soil pH conditions, although active Fe reacts with apatite and reactivity is affected by the form and amount of active Fe. The amounts of apatite P dissolved by organic acids were also dependent on solution pH. Although the dissolution of apatite by organic acids was observed even at the final pH of 5-6, dissolution with dilute HCl was not observed under the above pH range. This can be attributed to the ability of those organicacids to form chelate compounds with Ca in apatite, resulting in the release of P in the apatite into the liquid phase. The mode of dissolution by oxalate solution was different from that by citrate solution. In lower pH conditions (final pH<4.5), the amount of dissolved P by oxalate solution did not increase with reduction in final pH. This might result from the formation of a coated layer due to precipitated Ca oxalate at the surface of apatite, which prevents further reaction of oxalate and apatite.
社団法人日本土壌肥料学会の論文
2000-02-05

新鮮火山灰に含まれるアパタイトと土壌-植物系における主な活性成分との短期間における反応性

スポンサーリンク

概要

著者

関連論文

スポンサーリンク