西北石灰性土壤阳离子交换量测定方法比较

Comparison of Two Methods for Determination of Soil Cation Exchange Capacity of Calcareous Soil in Northwest China

阳离子交换量是评价土壤保肥性能和缓冲性能的重要指标,也是改良土壤和合理施肥的重要依据之一。为了给西北石灰性土壤阳离子交换量的测定提供科学依据,通过平行性实验、标准物质检测、实际样品检测,分析比较了目前普遍采用的测定方法乙酸钙交换法和三氯化六氨合钴浸提-分光光度法的优劣。结果表明,2种分析方法均具有较好的精密度和准确度,均适合西北地区石灰性土壤阳离子交换量的测定。从测定结果来看,三氯化六氨合钴浸提-分光光度法的土壤阳离子交换量测定值略高于乙酸钙交换法,在实际样品检测中相对标准偏差介于3.47%~9.46%。但相比之下乙酸钙交换法具有试剂成本较低的优势,而三氯化六氨合钴浸提-分光光度法具有节省时间的优势,检测人员可根据实际情况灵活选择使用。

Soil cation exchangeable capacity(CEC)is an important index to evaluate the fertilizer retention capacity and buffer capacity of soil.In order to provide reference for the determination of the cation exchangeable capacity of calcareous soil in northwest China,major differences in precision and accuracy between calcium acetate exchange method and hexamine cobaltic chloride exchange method were compared and studied by the parallel tests,standard substance testing and actual sample detection.The result showed that both analysis methods had good precision and accuracy,which were suitable for the determination of the cation exchangeable capacity of calcareous soil in northwest China.Compared with the two analysis methods,data from hexamine cobaltic chloride exchange method were higher compared with that of calcium acetate exchange method and the relative standard deviationsin the actural sampledetection were between 3.47%to 9.46%,the calcium acetate exchange method has the advantages of lower reagent cost,and the spectroph otometry method using hexammine cobaltic chloride digestion has the time-saving advantages.Therefrore,detectors may choose this two methods based on the actual circumstances.