Overview
EN ISO 17155:2020 - Soil quality: Determination of abundance and activity of soil microflora using respiration curves specifies a laboratory test method to measure the activity of active aerobic, heterotrophic microbial biomass in soils. The method monitors CO2 evolution or O2 consumption from unamended soils (basal respiration) and after addition of an easily degradable substrate (substrate‑induced respiration). It is intended for soil‑quality monitoring, evaluation of ecotoxic potential, and assessment of soils along contamination gradients or experimentally contaminated soils.
Key topics and technical requirements
- Measured parameters: basal respiration (RB), substrate‑induced respiration (RS), respiratory activation quotient (QR = RB/RS), specific growth rate (µ), time to peak (tpeakmax) and cumulative CO2/O2 evolution (CR).
- Substrate composition: glucose + ammonium + phosphate. The standard gives a substrate mix (80 g glucose, 13 g diammonium sulfate, 2 g KH2PO4) to prepare the test material.
- Dose and sample handling:
- Pre‑incubation: moist samples at ~40–60% of maximum water‑holding capacity, 20 °C for 3–4 days.
- Substrate addition: typically 10 mg substrate per g soil (dry mass); for soils with >5% organic matter, add 0.2 g substrate per g humus.
- Recommended at least three replicates per sample.
- Apparatus and conditions: continuous respirometer maintained at constant temperature (preferably 20 °C); measurement intervals typically hourly until steady basal rates and post‑substrate peak are observed.
- Toxicity testing guidance: test design using logarithmic concentration series (five concentrations plus control) in triplicate; guidance on spiking soils (aqueous, solvent or solid carrier), and selection of soils with low organic carbon (0.5–1.5%) for chemical bioavailability testing.
- Sample characterization: particle size, water content, water‑holding capacity, pH, organic carbon - measured according to referenced ISO methods.
Applications
- Monitoring soil quality and microbial health in environmental assessments.
- Evaluating ecotoxicological effects of chemicals and contaminated sites.
- Comparing microbial biomass/activity across contamination gradients or before/after remediation.
- Research into soil microbial dynamics, biodegradation potential and land‑use impacts.
Who uses this standard
- Environmental testing laboratories
- Soil scientists and ecotoxicologists
- Environmental consultants and remediation practitioners
- Regulatory agencies and research institutes conducting soil quality assessments
Related standards
Normative references cited by EN ISO 17155:2020 include:
Keywords: EN ISO 17155:2020, soil quality, soil microflora, respiration curves, microbial biomass, basal respiration, substrate‑induced respiration, ecotoxicity testing.