火焰光度法测定土壤中速效性钾含量的不确定度评定

Evaluation of Uncertainty of Determination of Exchangeable Potassium in Soil by Flame Photometry

依据NY/T 889-2004标准,以中性乙酸铵作为浸提剂,用火焰光度计测定了土壤中速效钾的含量,建立数学模型。结果表明:确定测量不确定度的因素,评估各个不确定度分量,给出了该方法的标准合成不确定度及扩展不确定度,如实反映了测量的置信度和准确度。当土壤中速效性钾含量为183.2mg·kg-1时,置信概率p=0.95时,本方法的标准合成不确定度为4.21mg·kg-1,扩展不确定度为8.42mg·kg-1(k=2)。

According to NY/T 889-2004, taking neutral ammonium acetate as the extraction agent, the content of available potassium in the soil was determined by using flame photometer,mathematics model was builded, elements of measurement uncertainty was identified, components of each uncertainty were evaluated, standard compound uncertainty and extension uncertainty of this method were put forward. When exchangeable potassi- um content of soil was 1. 832 mg· kg^-1 , confidence probability p = 0.95, standard compound uncertainty was 4.21 mg· kg^-1 ,the extension uncertainty was 8.42 mg· kg^-1（k=-2）of this method.