ISO 20978:2020
p
ISO 20978:2020
69678

Abstract  Preview

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.


General information 

  •  :  Published
     : 2020-05
  •  : 1
     : 15
  •  : ISO/TC 134 Fertilizers, soil conditioners and beneficial substances
  •  :
    65.080 Fertilizers

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