Silicomolybdenum Blue Colorimetric Determination of Available Si in Calcareous Soils  

作　　者：XUGUOHUA ZHENGWENJUAN 等 

机构地区：[1]DeprtmentofNaturlaResourcesandEnvironmentalSciences,NanjingAgriculturalUniversity,Nanjing210095,China

出　　处：《Pedosphere》1996年第3期279-284,共6页土壤圈（英文版）

摘　　要：This paper deals with the determination of available Si content in calcareous soils with Mo blue colorimetric analysis method.The experimental results showed that two acid reagents of sodium acetate buffering solution (pH 4) and 0.025 mol/L citric acid generally had a strong ability of extracting soil available Si,and theri soil filtrates were colorless,On the contrary,two alkaline extractants of 20 mg/mL sodium carbonate and 0.5 mol/L sodium bicarbonate only got a relevantly lower soil avaiable Si and theri extracts appeared deep color of organic and other pigments,which could be decolorized by adding certain amounts of P-free activated charcoal (about 0.1g/g soil),Int the procedure of Mo blue colorimetry,adding proper amount of oxalic acid and K(SbO)C4H4O6 could eliminate the interference of P to Si and Si to P,respectively.The concentration of acids was not the major factor suppressing the interferences between P and Si in the colorimetric analysis.In the medium of 0.2-0.8mole H×＋／L sulfuric acid,the intensity of the silicomolybdate blue color did not vary with acidity,no matter whether(NH4)2 Fe(SO4)2 or ascorbic acid was used as reductive reagent.About 10 minutes was needed to from a fully blue complex at 20-25°C，After 30 minutes,the blue color would slowly change into light one,and hence,the colorimetric process should be finished within a short time.

关 键 词：石灰土 有效硅 硅 硅钼蓝色度测量度 

分 类 号：S155.291[农业科学—土壤学] S151.93[农业科学—农业基础科学]