基于有机肥料新标准的有机质测定方法分析

选取不同种类的有机肥料,分别用灼烧法、NY 525-2002和NY 525-2012中的重铬酸钾氧化法测定有机质含量,比较不同检测方法测得有机质结果,分析了检测影响因素及有机肥料新标准与旧标准在测量结果上的差异,并做了加标回收率试验。结果表明,有机肥料新标准中,重铬酸钾溶液浓度虽然从原来的0.3 mol/L提高到0.4 mol/L,但随着浓硫酸浓度的大幅降低(从65%降低至49%),其氧化能力也随之减弱,在不乘氧化校正系数的前提下,测得有机质均小于旧标准所测值,下降幅度为1.08%～14.47%。根据肥料所含还原物质的量及氧化难易程度差别,不同种类有机肥料氧化校正系数范围为1.24～1.54,计算结果统一乘以1.5,会导致一部分有机质数据偏高,甚至超过100%。

Analysis of Assay Method for Organic Matter Based on Organic Fertilizer New Standard

The organic matter contents in different kinds of organic fertilizer were determined by the burning method,and the potassium dichromate oxidation method based on NY 525─2002 and NY 525─2012,respectively.The determination results obtained by different methods were compared,and the influential factors of detection results as well as the difference in determination results based on new and old organic fertilizer standard were analyzed by recovery test.The results showed that: in the new standard(NY 525─2012) of organic fertilizer,though the concentration of potassium dichromate solution was increased from original 0.3 mol/L to 0.4 mol/L,its oxidation capability was weakened because the concentration of concentrated sulfuric acid decreased to 49% from original 65%,therefore the organic matter contents determined by new standard were 1.08% ～ 14.47% lower than those did by old standard(NY 525─2002) on the premise of not considering oxidation correction coefficient.The oxidation correction coefficient of different kinds of organic fertilizer ranged from 1.24 to 1.54 according to their reducing substance content and oxidation difficulty.If the test results of organic matter content were unifiedly multiplied by 1.5,some organic matter data would be higher,even exceed by 100%.