Overview
ISO 11260:2018 - "Soil quality - Determination of effective cation exchange capacity and base saturation level using barium chloride solution" - specifies a standardized laboratory method to determine the cation exchange capacity (CEC) at the soil’s natural pH and to quantify exchangeable Na, K, Ca and Mg in air‑dried soils. The method uses a barium chloride saturation/leach sequence followed by displacement with magnesium sulfate; excess magnesium is quantified (typically by ICP‑AES). ISO 11464 is recommended for sample pre‑treatment.
Key topics and requirements
- Scope and applicability: Method applicable to all types of air‑dried soil samples; intended for determination of effective CEC and exchangeable major cations.
- Principle: Soils are saturated with barium (BaCl2), equilibrated at low ionic strength, displaced with MgSO4 and barium removed as BaSO4; excess Mg is measured to calculate CEC. Exchangeable Na, K, Ca and Mg can be measured in the 0.1 mol/L BaCl2 extract.
- Reagents and concentrations: Specifies analytical grade reagents and laboratory‑grade water (ISO 3696). Typical reagent examples in the standard include 0.1 mol/L and 0.0025 mol/L BaCl2 solutions and 0.0200 mol/L MgSO4 solution.
- Analytical measurement: Magnesium (for CEC) and exchangeable cations are determined by ICP‑AES (see ISO 22036) or other methods of comparable precision and detection limit.
- Quality control: Requires blanks, calibration series and a calibration‑check solution; provides performance characterization (calibration checks, repeatability and reproducibility).
- Interferences and checks: Notes interference from calcite, gypsum and soluble salts and recommends checking soil salinity via ISO 11265 (specific electrical conductivity). Colouration of extracts (organic matter dissolution) must be recorded.
Applications and users
- Practical for agronomy, soil fertility assessment, environmental monitoring, reclamation projects and research where accurate CEC and base saturation data guide lime and fertilizer recommendations.
- Typical users: soil testing laboratories, agronomists, environmental consultants, academic researchers, and regulatory agencies that require standardized, comparable soil chemistry data.
- Useful when baseline soil chemical properties are needed for nutrient management planning, soil classification or contaminant transport modelling.
Related standards
- ISO 11464 - soil sample pre‑treatment (recommended)
- ISO 11265 - determination of soil electrical conductivity (to check salinity interferences)
- ISO 3696 - water for analytical laboratory use
- ISO 22036 - guidance for ICP‑AES methods (instrumental determination)
Keywords: ISO 11260:2018, soil quality, cation exchange capacity, CEC, base saturation, barium chloride, exchangeable cations, ICP‑AES, soil testing, ISO 11464.
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