用连续流动分析仪测定土壤微生物态氮的方法研究

DETERMINATION OF SOIL MICROBIAL BIOMASS NITROGEN BY CONTINUOUS FLOW ANALYTICAL SYSTEM

本文在用连续流动分析仪 Ｔ Ｒ Ａ Ａ Ｃ Ｓ２０００ 测定土壤中常见十几种有机态氮化合物的基础上，对连续流动分析仪法和凯氏法测定土壤浸提液全氮和土壤微生物态氮的方法进行了比较研究。结果表明，连续流动分析仪所测标准有机态氮化合物的回收率平均为９４ ％ ；连续流动分析仪测得浸提液中全氮量与凯氏定氮法所测浸提液中全氮量之间呈显著线性正相关；连续流动分析仪法测得的土壤微生物态氮与凯氏法测得的土壤微生物态氮的之间亦呈显著线性正相关，表明两种方法测得的氮来自土壤氮的同一组分，其转换系数分别为 Ｋｎ ＝ ０４８（ Ｃａ Ｃｌ２ 浸提） 或 Ｋｎ ＝０５３（ Ｋ２ Ｓ Ｏ４ 浸提） 。

In order to simplify measurement of soil microbial biomass nitrogen(SMB?N), a study on comparison of total nitrogen (N tot ) in soil extraction and SMB?N estimated by continuous flow analytical system (CFA) and Kjeldahl digestion methods was conducted based on determination of nitrogen partions existing normally in soil extraction The results showed that the recovery of standard organic nitrogen of various components reached to a mean value of 94%, and there existed significant correlation and similar tendency of content of N tot and SMB?N measured by CFA and Kjeldahl methods The amount of SMB?N estimated by CFA method accounted for 78% or 84% of that estimated by the Kjeldahl method and these observations all come from the same fraction of the soil nitrogen The Kn value for determination of soil microbial biomass nitrogen by CFA method should corrected to Kn=0 48 (CaCl 2 as extractant) or Kn=0 53 (K 2SO 4 as extractant)