Determination of Total Carbon in Soil by Dry Combustion (Elementary Analysis) with Sundy SDCHN636  Carbon, Hydrogen and Nitrogen Analyzer According to ISO 10694

Introduction

Soil serves as the material foundation of agricultural production and an important carrier for the survival and reproduction of living organisms. With the continuous advancement of science and technology, particularly the deepening understanding of soil functions and their ecological roles, the perspective of contemporary soil material cycling helps reveal the biogeochemical nature of elements in soil. This understanding has led to greater emphasis on the importance of dynamic changes in soil nutrient elements in agricultural and ecological systems.

Carbon, as the fundamental constituent element of all organic matter in nature, occupies a central position in the soil biogeochemical cycle. Studies have shown that the soil carbon pool is not only a key component of the global carbon balance but also an important factor in maintaining ecological stability. Current research on soil carbon mainly focuses on its forms, activity, and interactions with global change, highlighting the importance of understanding the soil carbon cycle for addressing climate change.

Method Reference

ISO 10694 Soil quality — Determination of organic and total carbon after dry combustion (elementary analysis)

Principle

The carbon present in the soil is oxidized to carbon dioxide (CO₂) by heating the soil to at least 900 °C in a flow of oxygen-containing gas that is free from carbon dioxide. The amount of carbon dioxide released is then measured by using an infrared detection method.

Instrument and Basic Parameters

SDCHN636 Carbon, Hydrogen and Nitrogen Analyzer: an instrument for the determination of total carbon content by combusting the sample at a temperature of at least 900 °C (typically 950 °C in this application), equipped with a detector for measuring the carbon dioxide generated.

NOTE SDCHN636 Carbon, Hydrogen and Nitrogen Analyzer is capable of simultaneously determining total nitrogen and total carbon in soils.

（1）Method Parameters

Typical settings are listed below:

Combustion tube: 950 °C

（2） Carrier and Combustion Gases

Oxygen, high purity (99.999%)
Helium, high purity (99.999%)

（3）Calibration substances

Calcium carbonate (CaCO₃) or other suitable reference materials, e.g. acetanilide (C₈H₉NO), atropine (C₁₇H₂₃NO₃), spectrographic graphite powder (C), and potassium hydrogen phthalate (C₈H₅KO₄).

（4） Consumables

Tin foil cup
Ceramic Crucibles
Combustion tube

Laboratory sample

Use the fraction of particles less than 2 mm of air-dried soil samples pretreated according to ISO 11464. Use part of the laboratory sample to determine the water content according to ISO 11465.

Procedure

（1） Calibration of the Apparatus

Calibrate the apparatus as described in the relevant manual. For calibration or establishing a calibration graph, use one of the substances listed in 4.3.

（2） Determination of the Total Carbon Content

Weigh out about 100 mg of the air-dried sample in a tin foil cup (4.4). Carry out the analyses in accordance with the instrument operation manual.

Typical Results

The typical results are shown in Table 1.

Summary

The repeatability of the total carbon test procedure was evaluated using three soil samples, with triplicate parallel determinations for each sample. The carbon content determinations satisfied the conditions specified in Table 1 of ISO 10694. The SDCHN636 Carbon, Hydrogen and Nitrogen Analyzer fully meets the requirements of ISO 10694 Soil quality — Determination of organic and total carbon after dry combustion (elementary analysis).

For more information about the Sundy SDCHN636 Elemental Analyzer, please contact us by phone or email.

Phone: +86-731-88112150
Email: sales@sundytech.com