Annex II — METHODOLOGIES

Part A: methodology for determining the number and location of sampling points and for the sampling survey ActivityMinimum criteria for methodology 1. Determination of sampling points (sampling survey) for soil health assessment 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) 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) 2. Field sampling survey 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 Part B: methodology for determining or estimating the values of soil descriptors Where a reference methodology is set out in the table below, the following methodologies are to be used in accordance with Article 9: the reference methodology, a methodology equivalent to the reference methodology, or another methodology, provided that it is available in the scientific literature or publicly available and a validated transfer function is available. If a CEN methodology is available, it shall be preferred over the reference methodology. In that case, the initial reference methodology shall be considered to be an equivalent methodology. Soil descriptorReference methodologyMinimum methodological criteriaValidated 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 sedimentationNot applicableYES Electrical conductivityOption 1: ISO 11265 Determination of the specific electrical conductivity Option 2: saturated soil paste extract (eEC) measurement method (FAO SOP: GLOSOLAN-SOP-08) Not applicableYES Soil erosion rateSoil 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: soil characteristics (e.g. erodibility, soil crusting, soil roughness, stoniness) topography (e.g. slope steepness and length) climate (e.g. rainfall erosivity – intensity and duration) vegetation cover, crop type, land use and management practices to control or reduce erosion management practices (e.g. cover crops, reduced tillage, mulching, etc.) burned areas Not applicable Soil erosion by wind shall be assessed by considering the following factors: soil characteristics (e.g. erodibility) climate (e.g. soil moisture, wind speed, evaporation) vegetation (e.g. crop type) management practices to control or reduce erosion (e.g. wind breaks) 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 applicableYES SOC stocksMethodology as set out in Annex V to Regulation (EU) 2018/1999 in accordance with the 2006 IPCC Guidelines for National Greenhouse Gas InventoriesNot applicableYES Bulk density in subsoilISO 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 fragmentsYES Extractable phosphorusPreferred: ISO 11263 for spectrometric determination of phosphorus soluble in sodium hydrogen carbonate solution (P-Olsen) Other methods may be used as an alternative Not applicableYES concentration of heavy metals in soil: As, Sb, Cd, Co, Cr (total), Cu, Hg, Pb, Ni, Tl, V, Zn concentrations of other contaminants (including PFAS, pesticides and their metabolites) defined or selected by Member States 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 availableFor 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 conductivityMethodology to determine the value for one sample point: (1) Soil water holding capacity and air capacity: 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: for the area of soil not sealed or areas that did not undergo soil removal, estimate the total value of soil water holding capacity, air capacity and saturated hydraulic conductivity for the area of sealed and removed soils, consider setting the water holding capacity, air capacity and saturated hydraulic conductivity of impervious areas to zero, attributing proportionately intermediate values to semi-impervious and other artificial areas YES (for point value) (2) Saturated hydraulic conductivity: 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 soilOption 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 applicableYES Soil acidityISO 10390 for determination of pH in H2O, KCl and CaCl2 extractNot applicableYES Base saturation and exchangeable concentrations of sodium, potassium, calcium and magnesiumISO 11260 for determination of effective cation exchange capacity and base saturation level using BaCl2Not applicableYES Bulk density in topsoil (A-horizon)ISO 11272 for determination of dry bulk densityMethodology may be refined depending on the proportion of coarse fragmentsYES Soil descriptors linked to soil biodiversity and biological activityUse 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 availableNot applicable Part C: minimum methodological criteria for determining the values of the soil sealing and soil removal indicators For the soil sealing and soil removal indicators, the methodologies used shall comply with the definitions set out in Article 3 and Annex I. Such methodologies shall make use of at least the Copernicus services or, preferably, best available data including remote-sensing images, which shall be supplemented with relevant national inventories. For the settlement area indicator, Member States may use data collected under Regulation (EU) 2018/841, provided that such data are reported at soil district level. The methodologies chosen shall either be available in the scientific literature or publicly available.