ALKALINE PERSULFATE OXIDATION FOR DETERMINING TOTAL NITROGEN IN MICROBIAL BIOMASS EXTRACTS
ALKALINE PERSULFATE OXIDATION FOR DETERMINING TOTAL NITROGEN IN MICROBIAL BIOMASS EXTRACTS
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DOI：
10.2136/sssaj1993.03615995005700040021x
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发表时间：
1993-07-01
影响因子：
2.9
通讯作者：
BEARE, MH
中科院分区：
文献类型：
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作者：
CABRERA, ML;BEARE, MH
测定土壤微生物氮的三氯甲烷熏蒸-提取法包括用0.5 M K2 SO 4提取三氯甲烷熏蒸和三氯甲烷未熏蒸的样品，然后测定提取物中的总氮。总氮通常通过凯氏定氮消化（TKN）测定，其中包括NO2-和NO3-存在。通过TKN测定总氮有几个程序上的限制，如初始浓缩步骤，消化时间长，催化剂盐引起的相当大的冲击。相比之下，通常用于测定海水和淡水样品中总氮的过硫酸盐氧化法（TPN）不需要浓缩步骤，比TKN简单和快速得多。本研究的目的是评估和调整TPN法测定0.5 M K2 SO 4浸提液中的总氮，用于测定土壤微生物生物量氮。研究了试剂/样品（R/S）比和高压灭菌时间的优化，并评估了C和N浓度的影响。这些研究表明，在C/N比为10：1的情况下，在含有多达250 mg葡萄糖-C L-1的浸提液中，R/S比为1，高压灭菌时间为30 min时，可以获得完全的N回收。对12种CHCL 3熏蒸土壤提取物进行的优化TPN方法与TKN方法的比较表明，两种方法的氮回收率相同。在0.5 M K2 SO 4浸提液中使用TPN方法应有助于更快速有效地测量土壤微生物生物量N。
The CHCl3 fumigation-extraction method for determining soil microbial N involves the extraction of CHCl3-fumigated and CHCl3-unfumigated samples with 0.5 M K2SO4, followed by determination of total N in the extracts. Total N is typically determined by Kjeldahl digestion (TKN) with the inclusion of NO2- and NO3- present. The determination of total N by TKN has several procedural constraints such as an initial concentration step, long digestion times, and considerable bumping caused by catalyst salts. In contrast, a persulfate oxidation method (TPN) commonly used for determination of total N in sea- and freshwater samples does not require a concentration step and is much simpler and faster than TKN. The objective of this study was to evaluate and adapt the TPN method to measure total N in 0.5 M K2SO4 extracts for determination of soil microbial biomass N. Studies were conducted to optimize reagent/sample (R/S) ratio and autoclaving time, and to evaluate the effects of C and N concentrations. These studies showed that complete N recovery can be obtained with a R/S ratio of 1 and an autoclaving time of 30 min in extracts containing as much as 250 mg glucose-C L-1 at a C/N ratio of 10:1. A comparison of the optimized TPN method to TKN for extracts of 12 CHCL3-fumigated soils indicated that the methods gave the same N recoveries. The use of the TPN method in 0.5 M K2SO4 extracts should facilitate more rapid and efficient measurements of soil microbial biomass N.