Phosphorus Sorption and Desorption of Upland Soils in the Hilly Areas of Taihu Lake Watershed

Abstract

旱地土壤中流失的磷是地表水体中磷的重要来源,本文通过模拟实验对比太湖地区丘陵旱地土壤和水稻土对磷的吸持解吸特征,结果表明虽然旱地土壤对磷的固定能力略高于水稻土,但由于旱地土壤的有效磷水平普遍高于水稻土,因而前者磷的吸持饱和度(DPS)要大大高于后者,这就决定了旱地土壤中的磷被淋溶或以溶解态随径流流失的风险和数量也显著高于水稻土.磷吸持饱和度是土壤磷素水平和土壤固磷能力的综合指标,更能反映土壤固相中的磷进入液相的难易程度,可以作为评价水-土界面磷迁移能力的重要指标.;Phosphate sorption isotherms were determined for representative upland and paddy soils in Taihu Lake watershed.P desorped from the soils were also studied by successive extractions with iron oxide-impregnated paper st rips.Although the averaged P sorption maxima of upland soils derived from Langmuir sorption plot was a lit tle higher than thatof paddy soils the po tential of P loss from upland soils to waterbodies was greater because upland soils usually had a much higher P level.The Deg ree of Phosphorus Saturation (DPS), an integrated expression of soil P level and soil sorption capacity, can give good estimate of the amountof P desorped from soils so it can be used as a reliable index to assess the potential of soil P loss via leaching or surface runoff.