ISO INTERNATIONAL STANDARD 10694 First edition 1995-03-01 Soil quality - Determination of organic and total carbon after dry combustion (elementary analysis) Qualité du sol - Dosage du carbone organique et du carbone total apres combustionseche (analyseélementaire) ISO Reference number iSO 10694.1995(E) No reproduction or networking permited without license from IHS e with ISO Not for Resale IS0 10694:1995(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through isO which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with IsO, also take part in the work. Iso collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. ISO/TC 190, Soil quality. Subcommittee sC 3, Chemical methods and soil characteristics. Annexes A and B of this International Standard are for information only. iSO1995 or utiized in any formorbyany means,electronic or mechanical,includingphotocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization CasePostale56·CH-1211Geneve20·Switzerland Printed in Switzerland ii Copyright International Organization for Standardization r networking permitted without license from IHS Not for Resale ISO 10694:1995(E) INTERNATIONAL STANDARD ISO Soil quality -- Determination of organic and total carbon after dry combustion (elementary analysis) Scope ISO 11465:1993,Soil qualityDetermination of dry matter and water content on a mass basis This International Standard specifies a method for the Gravimetric method. determination of the total carbon content in soil after dry combustion.The organic carbon content is calcu lated from this content after correcting for carbonates 3 Principle present in the sample. If carbonates are removed be- forehand, the organic carbon content is measured di- The carbon present in the soil is oxidized to carbon rectly. dioxide (CO2) by heating the soil to at least 900 °C in a flow of oxygen-containing gas that is free from car- This International Standard is applicable to all types bondioxide.Theamountof carbondioxide released of air-dried soil samples. is then measured by titrimetry.gravimetryconduc- tometry, gas chromatography or using an infrared de- tection method, depending on the apparatus used. When the soil is heated to a temperature of at least 900 'C, any carbonates present are completely de 2 Normative references composed. For the determination of the organic car bon content, any carbonates present are previously The following standards contain provisions which, removed by treating the soil with hydrochloric acid. through referencein this text,constituteprovisions Alternatively, if the carbonate content of the examined of this International Standard. At the time of publica- samples is known and corrections are made for the tion, the editions indicated were valid. All standards carbonates present when the organic carbon content are subject to revision, and parties to agreements is calculated. based on this International Standard are encouraged NOTE 1 When the pH-CaCl2 is less than 6,5, the pres- to investigate the possibility of applying the most re- cent editions of the standards indicated below. ence of carbonates is unlikely.For example,this combina- tion of low pHand presence of carbonates is only possible Members of IEC and ISO maintain registers of cur- in recently limed soils. rently valid International Standards. IS0 3696:1987, Water for analytical