ISO 20978:2020

ISO 20978:2020

May 2020
International standard Current

Liming material - Determination of neutralizing value - Titrimetric methods

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 % P2O5. For a more accurate agronomic assessment of products containing more than 3 % P2O5, 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 P2O5 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 H2O and CO2. 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.

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Main informations

Collections

International ISO standards

Publication date

May 2020

Number of pages

15 p.

Reference

ISO 20978:2020

ICS Codes

65.080   Fertilizers

Print number

1
Sumary
Liming material - Determination of neutralizing value - Titrimetric methods

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 % P2O5. For a more accurate agronomic assessment of products containing more than 3 % P2O5, 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 P2O5 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 H2O and CO2. 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.

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