ISO 10694:1995

Overview

ISO 10694:1995 - "Soil quality - Determination of organic and total carbon after dry combustion (elementary analysis)" specifies a laboratory method for measuring total carbon in air-dried soils by dry combustion and for reporting organic carbon after correction for, or removal of, carbonates. The standard applies to all types of air-dried soil samples and defines the principle, apparatus, reagents, sample pretreatment and calculation procedures for soil carbon determination using combustion at temperatures of at least 900 °C.

Key topics and technical requirements

• Principle: Oxidize soil carbon to CO2 by dry combustion (≥900 °C) in an oxygen-containing, CO2‑free gas stream; measure CO2 released by titrimetry, gravimetry, conductometry, gas chromatography or infrared detection.
• Organic vs total carbon:
  • Total carbon is measured directly after combustion.
  • Organic carbon is calculated by correcting total carbon for carbonate carbon (determined separately), or measured directly after removing carbonates by HCl treatment.
• Sample preparation:
  • Use air-dried soil, fraction