ISO INTERNATIONAL STANDARD 15959 Firstedition 2016-07-15 FertilizersDeterminationof extracted phosphorus Engrais-Dosageduphosphore extrait Reference number ISO15959:2016(E) ISO Intemational Organization for Standardization IS02016 No reproduction or itted without license from IHS IS0 15959:2016(E) COPYRIGHTPROTECTEDDOCUMENT IS02016,Published inSwitzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8. CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +4122 749 09 47 [email protected] www.iso.org Intemationaibr PrganizationforStandardization networking permited without license from IHS IS0 15959:2016(E) Contents Page Foreword ..iv 1 Scope ..1 2 Normativereferences 3 Terms and definitions ..1. 4 Principle 5 Samplingandsamplepreparation ..1 6 Reagents. .1 7 Apparatus ..2 8 Procedure .3 8.1 Treatmentofthesolution .3 8.2 Hydrolysis.. 3 8.3 Weighingthecrucible .3 8.4 Precipitation .3 8.5 Filtering and washing .3 8.6 Drying and weighing. .4 8.7 Blanktest. 4 8.8 Verification 4 9 Calculation and expression of the result 10 Precision .5 10.1 Interlaboratory tests .5 10.2 Repeatability 10.3 Reproducibility .5 11 Test report .6 AnnexA(informative)Statisticalresults oftheinterlaboratorytest .7 Bibliography 9 iii ithout license from IHS