ISO 10573-1995 PDF

Full title and description

ISO 10573:1995 — Soil quality — Determination of water content in the unsaturated zone — Neutron depth probe method. This International Standard specifies an in situ, non‑destructive procedure for measuring soil volumetric water content in the unsaturated zone using a neutron depth probe; it is intended to produce water‑content profiles by measuring at a series of depths.

Abstract

The standard describes the measurement principle (fast neutrons thermalized mainly by hydrogen atoms), required apparatus (neutron probe and access tubes), field calibration against reference samples (gravimetric method), counting procedures, corrections for bulk density and soil composition, safety/handling considerations for the radioactive source, and reporting of volumetric water‑content profiles. The method is particularly suitable for rapid, repeated measurements at fixed locations but has relatively limited depth resolution compared with some alternative techniques.

General information

• Status: Published; International Standard (confirmed in systematic review).
• Publication date: 27 December 1995 (Edition 1, 1995).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 13.080.40 — Hydrological properties of soils / Soil quality.
• Edition / version: Edition 1 (1995).
• Number of pages: 13 pages.

Scope

Applies to in situ investigations of water storage, water balance and water distribution in the unsaturated zone of soils where rapid, repeatable measurements at fixed locations are required. The standard covers installation of access tubes, probe and detector specifications, calibration against gravimetric samples, measurement and counting procedures at multiple depths, required corrections (for bulk density, soil composition and matrix effects), and reporting; it also highlights safety requirements for handling the neutron source. The method is suitable down to depths within the local phreatic level and is useful for field profiling but offers coarser depth resolution than some other methods.

Key topics and requirements

• Measurement principle: fast neutrons emitted by a source are thermalized primarily by hydrogen atoms; detector count rate relates to hydrogen (water) concentration.
• Apparatus: neutron depth probe (source and detector), access tube installation and dimensions, and counting equipment specifications.
• Field calibration: use of gravimetric reference samples (drying method) and conversion to volumetric water content, with procedures for site‑specific calibration.
• Corrections and limitations: adjustments for bulk density, soil matrix composition, measurement volume/influence, and recognition of limitations in stony or highly heterogeneous soils.
• Safety and regulatory considerations: handling, transport and use of the radioactive neutron source (radiation safety best practices and national regulations).
• Reporting: recommended format for depth‑wise volumetric water content, calibration data, measurement uncertainty, and field conditions.

Typical use and users

Used by soil scientists, hydrologists, agronomists, environmental consultants, groundwater and vadose‑zone researchers, and civil engineers for field studies of soil water storage, irrigation scheduling research, water‑balance investigations, contaminant transport studies, and monitoring where repeated, rapid profiling at fixed sites is required. Users should have training in neutron probe operation and radiation safety.

Related standards

Commonly referenced and complementary documents include ISO 11461 / ISO 11465 (gravimetric determination of soil water content used for calibration), ISO 11272 (determination of dry bulk density) and other soil‑water and geotechnical water‑content standards; radiation safety guidance from IAEA/ICRP and national regulators is also relevant when using neutron probes.

Keywords

ISO 10573, soil quality, water content, unsaturated zone, neutron depth probe, soil moisture profiling, in situ measurement, field calibration, volumetric water content, access tube, radiation safety.

FAQ

Q: What is this standard?

A: An ISO International Standard (ISO 10573:1995) that specifies an in situ, non‑destructive method for determining soil water content in the unsaturated zone using a neutron depth probe.

Q: What does it cover?

A: It covers the measurement principle, required apparatus (probe and access tubes), field calibration procedures (reference gravimetric sampling), measurement and counting methods at multiple depths, corrections for soil properties, reporting formats, and safety considerations for the radioactive source.

Q: Who typically uses it?

A: Soil scientists, hydrologists, environmental and agricultural researchers, consultants and engineers performing water‑balance studies, monitoring and research that require repeated in situ soil moisture profiling. Operators must be trained in neutron probe use and radiation safety.

Q: Is it current or superseded?

A: ISO 10573:1995 remains a published International Standard; it has been periodically reviewed and was confirmed in ISO's review process (the edition published in December 1995 is the current confirmed version as listed by ISO). Users should check national regulations and newer measurement standards or methods for specific applications.

Q: Is it part of a series?

A: It forms part of ISO/TC 190 "Soil quality" documents addressing soil water content and related properties; it is complementary to gravimetric water‑content methods (ISO 11461/11465), bulk density standards (ISO 11272) and other soil‑quality procedures used together for calibration and interpretation.

Q: What are the key keywords?

A: Neutron depth probe, soil water content, unsaturated zone, in situ measurement, volumetric water content, access tube, field calibration, radiation safety.