ISO 20978:2020 pdf download

ISO 20978:2020 pdf download.Liming material — Determination of neutralizing value — Titrimetric methods
1 Scope
This document specifies two methods for the determination of the neutralizing value (NV) of liming materials. Method A is applicable to all liming materials except silicate liming materials. NOTE 1 Examples of hard liming materials are limestone and dolomite. Examples of soft liming materials are chalk, marl and burnt lime. Method B is applicable to all liming materials. Neither method correctly takes into account the potential neutralizing value of material containing more than 3 % P 2 O 5 . For a more accurate agronomic assessment of products containing more than 3 % P 2 O 5 , EN 14984 [8] is used to determine the liming efficiency. NOTE 2 The methods described in ISO 6598 and ISO 7497 can be used for the determination of P 2 O 5 content. Further information on P analyses is given in References [5] and [6]. NOTE 3 Carbonate consumes H + and removes acidity in solution with subsequent dissociation to H 2 O and CO 2 . Forms of orthophosphate can consume H + but are not dissociated to molecular forms that remove acidity. The acidity is back titrated with alkali causing an underestimation of NV.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 3310-1, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 8157, Fertilizers and soil conditioners — Vocabulary
ISO 14820-2, Fertilizers and liming materials — Sampling and sample preparation — Part 2: Sample preparation
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8157 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Principle
Dissolution of the sample in a specified quantity of hydrochloric acid standard solution. Determination of the excess acid by back titration with a sodium hydroxide standard solution.
For products containing iron, a preliminary oxidization is necessary in method B.
5 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade.
NOTE Commercially available solutions can be used.
5.1 Water, according to ISO 3696, grade 3.