Overview
EN ISO 14254:2018 (ISO 14254:2018) is an international test method for assessing soil quality by measuring exchangeable acidity in soils extracted with a barium chloride solution. The standard specifies a laboratory procedure-mainly a fixed pH end point titration-to determine total exchangeable acidity in barium chloride extracts prepared according to ISO 11260. It is applicable to all types of air-dry soil samples and includes optional steps for determining free H+ acidity and aluminium in the extracts.
Key topics
- Scope and principle
- Extraction of air-dry soil using a 0.1 mol/l barium chloride solution (as per ISO 11260).
- Main determination: titration of the extract with NaOH to a fixed end point pH = 7.8 (or using phenolphthalein indicator when specified).
- Optional determinations
- Free H+ acidity: add sodium fluoride (NaF) to complex aluminium and isolate proton acidity.
- Aluminium quantification: by flame atomic absorption spectrometry (AAS) or inductively coupled plasma atomic emission spectrometry (ICP-AES).
- Reagents and calibration
- Use analytical-grade reagents and low-conductivity water; detailed reagent recipes and calibration solutions are specified.
- pH-meter calibration with buffer solutions and regular standardization of titrants (NaOH) are required.
- Apparatus and procedure
- Required equipment includes pH-meter with automatic temperature compensation, burettes (≤0.05 ml), magnetic stirrers; automatic titrimeters are allowed.
- Procedure sections cover sample pretreatment, water content determination, extraction, titration, calculations and test reporting.
- Limitations and notes
- The fixed pH end point method is not specific to individual acid species; the pH 7.8 end point is intended to precipitate Al3+ but may include weak organic acids.
Applications
- Routine laboratory measurement of soil acidity for:
- Environmental characterization and monitoring
- Agricultural soil fertility assessment and lime requirement estimation
- Land remediation and regulatory compliance testing
- Research into soil chemical properties and cation exchange processes
- Typical users: environmental testing labs, soil science researchers, agronomists, land managers, regulators and consultants who require standardized, traceable acidity data.
Related standards
- ISO 11260 - Preparation/extraction protocol (effective cation exchange capacity/base saturation using barium chloride)
- ISO 11464 - Sample pretreatment for physico-chemical analysis
- ISO 11465 - Gravimetric determination of dry matter and water content
- ISO 22036 - Determination of trace elements in extracts by ICP-AES
EN ISO 14254:2018 provides a standardized, reproducible method for quantifying exchangeable acidity in soils - a key parameter for soil quality assessment and agronomic decision-making.