ANNEX II METHODOLOGIES

Activity

Minimum criteria for methodology

The sampling survey shall be designed from a complete sample frame containing the best available information on the distribution of soil properties, such as information resulting from relevant measurements pursuant to Article 9(3) and (4)

The sampling scheme shall be a stratified random sampling optimised on the best available information on the variability of soil descriptors, and the stratification shall be based on the soil units established in accordance with Article 4(2). Sampling points related to measurements referred to in Article 9(4) may be taken into account partly or completely in the sampling scheme, regardless of their design

The number and location of the sampling points shall represent the variability of the chosen soil descriptors within the soil units, with a maximum error percentage (or coefficient of variation) of 5 %

The allocation and size of the sample shall be determined by applying appropriate procedures (e.g. the Bethel algorithm – Bethel, 1989 (1)) which are able to account for the required maximum estimation error

The sampling survey designed by the Member States for each monitoring cycle may change or remain the same

Further details on determining the number and location of sampling points are to be provided pursuant to Article 24(1), point (a)

Exact sampling locations shall be sampled unless duly justified circumstances, such as soil saturated with water or a high level of rock content, prevent the sampling of the locations

When soil composite samples are taken, they shall be a mixture of at least 5 subsamples

When sampling soil in non-forested areas, residues and organic debris shall be removed from the surface

When sampling soil in forested areas, the forest floor, if relevant subdivided into litter and organic layers, shall be sampled separately and the thickness and weight shall be recorded

Samples or subsamples for the composite sample shall, where possible, be taken to a depth of at least 30 cm of soil. Information such as soil type and if possible genetic soil horizons shall be recorded. Subsamples shall be mixed together in order to get a homogeneous composite sample. Sampling may be done by fixed depth or by horizon, but data shall be reported by fixed depth

Bulk density samples shall be undisturbed samples taken at the relevant depth, including below 30 cm for subsoil. Samples related to soil compaction (saturated hydraulic conductivity and air capacity) may be the same undisturbed samples as those taken for bulk density. Where high content of coarse fragments in soil prevents sample taking, sampling may be excluded in that location for measuring bulk density

Further details on the field sampling survey are to be provided pursuant to Article 24(1), point (a), including on how to handle specific situations such as shallow soils and different sampling depths

Soil descriptor

Reference methodology

Minimum methodological criteria

Validated transfer function required (if using a methodology different from the reference methodology)?

Soil texture (clay, silt and sand content – needed for the determination of other descriptors and related ranges)

ISO 11277 Determination of particle size distribution in mineral soil material – Method by sieving and sedimentation

Not applicable

YES

Electrical conductivity

Option 1: ISO 11265 Determination of the specific electrical conductivity

Option 2: saturated soil paste extract (eEC) measurement method (FAO SOP: GLOSOLAN-SOP-08 (2))

Not applicable

YES

Soil erosion rate

Soil erosion rate estimation shall take into account all actions taken to mitigate or compensate the erosion risk, including post-fire mitigation measures

Soil erosion rate estimation shall include all relevant erosion processes such as erosion by water, wind, harvest and tillage

Soil erosion by water shall be assessed by considering the following factors:

Not applicable

Soil erosion by wind shall be assessed by considering the following factors:

Soil erosion by management practices such as tillage or export of biomass shall be quantitatively assessed based on a methodology either available in the scientific literature or publicly available

Soil Organic Carbon (SOC)

ISO 10694 Determination of organic and total carbon after dry combustion, ensuring all carbon is incinerated

SOC shall be calculated by determining the total carbon content and subtracting the carbon present as carbonate, which shall be determined in accordance with ISO 10693

Not applicable

YES

SOC stocks

Methodology as set out in Annex V to Regulation (EU) 2018/1999 in accordance with the 2006 IPCC Guidelines for National Greenhouse Gas Inventories

Not applicable

YES

Bulk density in subsoil

ISO 11272 for determination of dry bulk density

Where an equivalent parameter is chosen, the methodology shall be either a European or international standard where available; if such standard is not available, the methodology chosen shall either be available in the scientific literature or publicly available

Methodology may be refined depending on the proportion of coarse fragments

YES

Extractable phosphorus

Preferred: ISO 11263 for spectrometric determination of phosphorus soluble in sodium hydrogen carbonate solution (P-Olsen)

Other methods may be used as an alternative

Not applicable

YES

For heavy metals:

ISO 54321: Aqua Regia

Optional: bioavailable fractions of contaminants, such as ISO 17586 using dilute nitric acid

For contaminants other than heavy metals: use European or international standards where available; if such standard is not available, the methodology chosen shall either be available in the scientific literature or publicly available

For heavy metals:

YES

For contaminants other than heavy metals: not applicable if European or international standards are not available

Soil water holding capacity, air capacity and saturated hydraulic conductivity

Methodology to determine the value for one sample point:

Option 1: LABORATORY: ISO 11274 for determination of the water-retention characteristic

Option 2: ESTIMATION: apply pedotransfer functions requiring input variables such as particle size distribution, bulk density, soil organic carbon concentration

Minimum criteria for estimating the total soil water holding capacity, the air capacity and the saturated hydraulic conductivity of a soil unit or on a river basin or sub-basin scale:

YES (for point value)

Option 1:

LABORATORY: ISO 17313: Determination of hydraulic conductivity of saturated porous materials

Option 2:

ESTIMATION: apply pedotransfer functions requiring input variables such as particle size distribution, bulk density, soil organic carbon concentration

Nitrogen in soil

Option 1:

ISO 11261 for determination of total soil nitrogen using a modified Kjeldahl method

Option 2:

ISO 13878 for determination of total nitrogen by dry combustion

Not applicable

YES

Soil acidity

ISO 10390 for determination of pH in H2O, KCl and CaCl2 extract

Not applicable

YES

Base saturation and exchangeable concentrations of sodium, potassium, calcium and magnesium

ISO 11260 for determination of effective cation exchange capacity and base saturation level using BaCl2

Not applicable

YES

Bulk density in ‘topsoil’ (A-horizon (3))

ISO 11272 for determination of dry bulk density

Methodology may be refined depending on the proportion of coarse fragments

YES

Soil descriptors linked to soil biodiversity and biological activity

Use European or international standards where available; if such standard is not available, the methodology chosen shall either be available in the scientific literature or publicly available

Not applicable