Foreword

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This document was prepared by Technical Committee ISO/TC 190, Soil quality.

This second edition cancels and replaces the first edition (ISO 20951:2019), of which it constitutes a minor revision. The changes are as follows:

editorial changes in Table 1 and Table 2;
adjustment of formatting throughout the text;
the Bibliography and references in the text have been updated.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

Greenhouse gas (GHG) emissions from soils are a major environmental concern. Global and national emission inventories have identified soils, in particular agricultural soils, as being a major contributor to these emissions, in particular nitrous oxide (N₂O), methane (CH₄) and carbon dioxide (CO₂) related to loss of soil organic matter. Agricultural soils are also major emitters of ammonia (NH₃), which is a precursor of N₂O. Changes in soil management should take account of these emissions as part of efforts to mitigate climate change.

GHGs and ammonia fluxes from soil are complex to measure. They are variable and heterogeneous as they are governed by weather and meteorological conditions (e.g. temperature and moisture regimes), soil characteristics (e.g. soil parental material, pH, clay content, cation exchange capacity) and, for managed soils, by the agricultural or forestry practices (e.g. crop and wood residues management, soil tillage or no-tillage, inputs of soil conditioner and fertilizers, irrigation). These factors generally interact and their effects on GHG emissions are still poorly quantified. This results in large uncertainties for the inventories of national and global agricultural emissions. For example, Freibauer, 2008^[1^] has estimated an uncertainty at 80 % for European (EU27) agricultural N₂O emissions. With the reinforcement of international and regional climate policies, comparable and reliable information is needed to report on GHG emissions but also to adopt and verify mitigation options.

No standard covers the measurement of GHGs and ammonia emissions from soils. However, several measurement methods have been developed. This document provides guidance on the main methods available to quantify the exchanges of greenhouse gases (CO₂, N₂O, CH₄) and ammonia (NH₃) between soils and the atmosphere. It is intended to help users to select the measurement method or methods most suited to their purposes by setting out information on the application domain and the main advantages and limitations of each method.

1 Scope

This document gives an overview and provides guidance on the main methods available to quantify the exchanges of greenhouse gases (CO₂, N₂O, CH₄) and ammonia (NH₃) between soils and the atmosphere.

It is intended to help users to select the measurement method or methods most suited to their purposes by setting out information on the application domain and the main advantages and limitations of each methods.

2 Normative references

3 Terms and definitions

4 Methods for measuring GHGs and ammonia fluxes between soil and the atmosphere

5 Concentration measurements and air sampling

5.1 General

5.2 Concentration measurement methods

5.3 Air sampling

6 Selection of the appropriate methods

7 Minimum information for reporting

Bibliography