ISO INTERNATIONAL STANDARD 13536 Firstedition 1995-06-15 Soil quality Determination of the potential cation exchange capacity and exchangeable cations using barium chloride solution buffered at pH = 8,1 Qualité du sol - Détermination de la capacite d'échange cationique potentielle et des teneurs en cations échangeables en utilisant une solution tampon de chlorure de baryum a pH = 8, 1 OSI Reference number ISO13536:1995(E) Copyright International Organization for Standardization Not for Resale ISO 13536:1995(E) Foreword ISO (the International Organization for s Standardization) is a worldwide federation of national standards bodies (isO member bodies). The work of preparing International Standards is normally carried out through Iso 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 Electrotechnicai Commission (lEC)onallmattersof electrotechnicalstandardization. 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. International Standard Iso 13536 was prepared by Technical Committee ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical methods and soil characteristics Annex A of this International Standard is for information only. ISO 1995 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced microfilm, without permission in writing from the publisher. International Organization for Standardization CasePostale56·CH-1211Geneve20·Switzerland Printed in Switzerland ii Poviah intematinal Oorganizatin for Standardization led without license from IHS Not for Resale INTERNATIONAL STANDARD ISO ISO 13536:1995(E) Soil quality - - Determination of the potential cation exchange capacity and exchangeable cations using barium chloride solution buffered at pH = 8,1 WARNING -- Barium is a very toxic element if ingested. The barium ion has health risks for laboratory personnel working with this chemical; it is also harmful for the environment. Scope Bascomb[3]. The CEC of soil samples is determined in barium chloride solution buffered at pH = 8,1 using ThisInternationalStandardspecifiesamethodforthe triethanolamine. determination of the potential cation exchange ca- pacity (CEC) of soil buffered at pH = 8,1 and of the The soil is first saturated with respect to barium by determination of the content of exchangeable sodium, treating the soil three times with buffered barium potassium, calcium and magnesium in soil. chloridesolution.Subseguentlyaknownexcessof 0,02 mol/l magnesium sulfate solution is added. All This international Standard is applicable to all types the barium present, in solution as well as adsorbed, of air-dried soil samples. isprecipitatedinthe formof highlyinsolublebarium sulfate and the sites with exchangeable ions are then Normative references readily occupied by magnesium. The excess 2 magnesium is determined by either flame atomic ab- The following standards contain provisions which sorption spectrometry (FAAS) or inductively coupled plasma atomic emission spectrometry (ICP-AES) through reference in this text, constitute provisions of this International Standard. At the time of publi- cation, the editions indicated were valid. All standards It is also possible to determine sodium, potassium, are subject to revision, and parties to agreements calcium and magnesium (and other elements) in the barium chloride extract of the soil. based on this InternationalStandard are encouraged to investigate the possibility of applying the most re- NOTES cent editions of the standards indicated below. Members of IEC and ISO maintain registers of cur- 1 Besides sodium, potassium, calcium and magnesium, it rently valid International Standards. is also possible to determine other cations, for