关键词: 低分子量有机酸, 红壤, 无机态磷, 酸度, 红松林, 敏感性指数, 凋落物质量, 土壤湿度, 凋落物分解

Abstract: Red soil samples collected from southern Hubei province and northern Jiangxi province were tested to analyze their inorganic phosphorus fractions,pHand active aluminum after incubated with added various organic acids.The results indicated that application of organic acids increased the content of Ca₂-P in both red soils,in the order of citric acid>malic acid>succinic acid>acetic acid,did not affect the contens of Ca₈-P and Ca₁₀-P,but usually reduced Fe P,Al Pand O P.The pHvalues of the soils treated by organic acids,except for acetic acid,were reduced by 0.65～1.96,compared with the control.Soil active Al extracted with 0.02 mol·L^-1 CaCl₂ in treatments with citric,malic and succinic acid was 5.7～51.3 tmes as the control,and Al extracted with 1 mol·L^-1 KCl also increased 4.0～67.3 times.However,acetic acid had little influence on active soil Al.It was concluded that in red soils, organic acid could improve phosphorus availability,but enhance the soil toxicity caused by active Al

Key words: Low molecular weight organic acid, Red soil, Inorganic phosphorus, Acidity, soil moisture, litter quality, litter decomposition, sensitivity index, Korean pine forest