ISO 23753-2:2019/Amd 1:2020

Overview

ISO 23753-2:2019/Amd 1:2020 is an internationally recognized amendment to the standard for assessing soil quality by measuring dehydrogenase enzyme activity in soils. This standard specifies the method using iodotetrazolium chloride (INT) to determine soil dehydrogenase activity, a key biological indicator of microbial activity and overall soil health. Published by the International Organization for Standardization (ISO), this amendment refines analytical procedures ensuring accurate enzyme activity quantification, crucial for environmental monitoring, agriculture, and soil science research.

Key Topics

• Dehydrogenase Activity in Soils: Enzymes known as dehydrogenases play an essential role in soil microbial metabolism. Measuring their activity provides insights into soil microbial function and vitality.
• INT Methodology: This method utilizes iodotetrazolium chloride (INT) as a substrate to form formazan compounds, which can be quantitatively analyzed through absorbance measurements.
• Amendment Highlights: The 2020 amendment updates the calculation procedure for enzyme activity by refining the formula for converting INTF concentrations into enzymatic activity in mU/g of dry soil.
• Standard Curve Use: Concentrations of INT-formazan (INTF) are determined using a standard curve plotting INTF concentration (nmol/ml) against absorbance. This linear model enables precise quantification.
• Calculation Formula:
  [ A = \frac{(C_c - C_s) \times V \times 100}{m \times D_M \times R_T} ]
  Where:
  • (A) = enzymatic activity (nmol/(min·g) dry soil)
  • (C_c) = INTF concentration in sample (nmol/ml)
  • (C_s) = INTF concentration in control (nmol/ml)
  • (V) = volume of reaction mixture (ml)
  • (m) = soil mass per tube (g)
  • (D_M) = dry matter content (%) per ISO 11465
  • (R_T) = reaction time (min)
  • Factor 100 adjusts for dry matter percentage

Applications

• Soil Health Monitoring: This standard method helps agronomists, soil scientists, and environmental specialists assess soil microbial activity, a critical indicator of soil fertility and ecosystem function.
• Biological Soil Quality Assessment: Organizations conducting soil quality evaluations use this method to understand microbial enzyme dynamics affected by pollutants, land use changes, or agricultural practices.
• Research & Development: Academic and industrial laboratories utilize this method for studying microbial processes, soil remediation efforts, and biogeochemical cycles.
• Environmental Impact Studies: Regulatory bodies apply this testing method for evaluating soil contamination and its biological consequences, supporting sustainable land management practices.

Related Standards

• ISO 11465: Describes the determination of dry matter content in soils, a key parameter used alongside ISO 23753-2 for calculating enzyme activity.
• ISO 23753-1: Covers related methods for determining dehydrogenase activity with alternative substrates and techniques.
• ISO/IEC Directives: Provide general guidance on developing and maintaining ISO standards ensuring consistency and quality in environmental testing protocols.

ISO 23753-2:2019/Amd 1:2020 is a pivotal standard for environmental scientists and soil quality professionals seeking reliable and internationally accepted procedures to measure enzymatic soil activity, supporting data consistency and promoting sustainable soil management worldwide. For detailed methodology and compliance, consult the official ISO documentation and your local ISO member body.