【摘要】 凯氏蒸馏法是土壤氮含量测定的经典方法,但费时费力,随着技术的发展,连续流动分析仪自动分析技术开始应用于氮测定。选择50个农田土壤和2个国家土壤标准物质（河南黄潮土GBW07413a和江西红壤GBW07416a）,利用硫酸+催化剂（K₂SO₄∶CuSO₄∶Se=100∶10∶1）进行消煮,将土壤全氮转化为铵态氮,消煮液中铵态氮分别用连续流动分析仪和自动凯氏定氮仪测定。结果表明,两种方法测定土壤全氮含量相比无明显差异,测定结果之间呈显著线性相关关系,回归直线方程为:Y（连续流动分析仪-N）=0.995 1X（自动凯氏定氮仪-N）+0.003 5,相关系数r=0.980（n=50,P<0.01）。对3个土壤样品和2个国家土壤标准物质采用连续流动分析仪分别重复测定7次,相对标准偏差均小于5%。国家土壤标准物质全氮测定值与标准确认值一致。连续流动分析仪测试速度快,试剂消耗量少,精密度和准确度满足要求,可用于大批量土壤全氮含量的分析测定。更多还原

【Abstract】 Various methods for assessing soil total nitrogen（N）have been developed to manage N nutrient and to understand N cycle in soil.Kjeldahl distillation-titration（KDT）has been used widely as a reference method for N determination in soils,but it is time consuming method.The objective is aimed at establishing a time saving method for determining of soil total N by a continuous flow analyzer（CFA）.Fifty soil samples and two standard samples were digested with H₂ SO₄ catalysts（K₂ SO₄∶Cu SO₄∶Se=100∶10∶1）.N contents in the digests were determined by a CFA and an automated KDT instrument,respectively.The result of t test found that there was no any significant difference of the soil contents measured by the CFA and the KDT method.A significant linear correlation could best describe the measured N values measured by both methods:Y（CFA-N）=0.995 1 X（KDT-N）+0.003 5.The pearson’s correlation coefficient was 0.980 with a significance level（n=50,P<0.01）.The CFA method for soil N measurement had a high precision with relative standard deviation（RSD）less than 5%.It is suggested that the CFA based on colorimetric detection of the pure ammonium chloride distillate（Berthelot reaction）can be used to determinate N in the Kjeldahl digests of soil samples.The CFA method is labor saving and can handle large numbers of samples.更多还原