Research on the Sulfur Forms and the Acidity in Acid Sulphate Soils (ASS)

Four profiles of acid sulphate soils and 20 Samplings were taken according to different soiltypes and land use patterns in Taishan city, Guangdong province. The different sulfur forms including to-tal sulfur, pyrite (FeS2), jarosite, water-soluble sulfur, exchangeable sulfur, element S and organic Sand soil pH etc. were analyzed and estimated. The data showed that the contet of the total sulfur is veryhigh in soils in this region, and the sulfur in ASS was mostly in inorganic forms and dominated by pyrite,water - soluble sulfur and exchangeable sulfur; the content of element S and organic S was relatively low.The total suifur and pyrite usually chang with a trend of increasing from soil surface horizon to bottom;jarisite, water - soluble sulfur and exchangeable sulfur had similar change trend in profile, they common-ly accumulated in layers with a certain pH or low pH values. Coefficients between pH and exchangeablesulfur, contents of jaresite and total suifur are -0.800 7, -0. 437 4 and - 0.572 9 respectively; thecomplicated relationship was found between pH and content of pyrite in soils. The occurrence of jarositehas important diagnostic sighficance in the soil development and classification.