# Foliar Samples Collection and LMA Ratio Determination

Denis Loustau, Christelle Aluome, Dario Papale

► To cite this version:

Denis Loustau, Christelle Aluome, Dario Papale. Foliar Samples Collection and LMA Ratio Determination. Instructions guide for measurements at the ICOS Ecosystem Stations, ICOS-ETC, University of Viterbo, 2017. hal-02786543

HAL Id: hal-02786543

https://hal.inrae.fr/hal-02786543v1

Submitted on 5 Jun 2020

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INSTRUCTIONS FOR

# SOIL SAMPLING AND PREPARATION

for monitoring the soil organic carbon and nitrogen

<table><thead><tr><td>Version</td><td>Release date</td><td>Summary of changes</td></tr></thead><tbody><tr><td>20170530</td><td>20170530</td><td>Explained labeling of soil bags, correction of wrong reference to annexes.</td></tr><tr><td>20180322</td><td>20180322</td><td>Corrected the units of SUMWA<sub>i,s</sub> and WA30<sub>i,s</sub> (kg m<sup>-2</sup>), suggested to exclude Post Office as carrier for samples transportation. Clarified that metadata and correct labelling of samples are mandatory for the analysis. Other minor textual editing.</td></tr><tr><td></td><td></td><td></td></tr><tr><td></td><td></td><td></td></tr><tr><td></td><td></td><td></td></tr></tbody></table>

The ICOS protocols and the derived Instructions documents can be changed and amended in time, because new methods become available or to improve their clearness. For this reason, it is crucial to keep track of the versions and differences.
CONTENTS

<table><tr><td>SUMMARY</td><td>3</td></tr><tr><td>OBJECTIVES AND DEFINITIONS</td><td>4</td></tr><tr><td>SOIL SAMPLING OVERVIEW</td><td>5</td></tr><tr><td>Determine if sampling is needed</td><td>5</td></tr><tr><td>Soil description</td><td>5</td></tr><tr><td>Measurement methods</td><td>7</td></tr><tr><td>Timing of soil sampling</td><td>8</td></tr><tr><td>SOIL SAMPLING PROCEDURE</td><td>9</td></tr><tr><td>Equipment</td><td>10</td></tr><tr><td>Generic equipment</td><td>10</td></tr><tr><td>Specific equipment for the frame technique</td><td>10</td></tr><tr><td>Specific equipment for the cylinder technique</td><td>10</td></tr><tr><td>Specific equipment for the water technique</td><td>10</td></tr><tr><td>Specific equipment for the sand technique</td><td>11</td></tr><tr><td>The manual frame method (organic and uppermost soil layer)</td><td>11</td></tr><tr><td>Step-by-step operation mode</td><td>11</td></tr><tr><td>The "Core" method with mechanical sampling (motor hammer corer)</td><td>12</td></tr><tr><td>Soil sample preparation in the field</td><td>12</td></tr><tr><td>The "Core" method with semi-mechanical sampling (root corer)</td><td>13</td></tr><tr><td>Excavation method (cylinder, water and sand techniques)</td><td>14</td></tr><tr><td>Cylinder technique</td><td>14</td></tr><tr><td>Step-by-step operation mode</td><td>15</td></tr><tr><td>Water and Sand techniques</td><td>16</td></tr><tr><td>Step-by-step operation mode</td><td>16</td></tr><tr><td>Special instructions for peat soils</td><td>17</td></tr><tr><td>SAMPLE PROCESSING</td><td>19</td></tr><tr><td>Equipment</td><td>19</td></tr><tr><td>Mineral soil samples</td><td>20</td></tr><tr><td>Step 1 - Drying and sieving each individual sample to obtain fine earth, stones and root mass values</td><td>20</td></tr><tr><td>Step 2 - Combining fine earth of individual samples to obtain a composite sample</td><td>22</td></tr><tr><td>Step 3 - Extracting three aliquots from the composite samples</td><td>23</td></tr></table>
<table><tr><td>Organic samples</td><td>27</td></tr><tr><td>Step 1 - Drying and crushing samples</td><td>27</td></tr><tr><td>Step 2 - Composite sample and aliquots extraction</td><td>27</td></tr><tr><td>MAINTENANCE OF TOOLS</td><td>29</td></tr><tr><td>DATA SUBMISSION</td><td>30</td></tr><tr><td>Soil sample packaging for laboratory analysis</td><td>30</td></tr><tr><td>Soil sample packaging for archiving</td><td>31</td></tr><tr><td>Data submission</td><td>32</td></tr><tr><td>ANNEX 1: SOIL TEXTURE CLASSES</td><td>33</td></tr><tr><td>ANNEX 2: MOTOR SAMPLING SYSTEM</td><td>34</td></tr><tr><td>Sampling and drilling systems</td><td>34</td></tr><tr><td>Material</td><td>34</td></tr><tr><td>Methods</td><td>35</td></tr><tr><td>Tripod System to suspend jackhammer</td><td>36</td></tr><tr><td>Example of commercial systems (light and heavy versions):</td><td>37</td></tr><tr><td>How to use a tripod</td><td>38</td></tr><tr><td>Adapt a jack Hammer to a tripod</td><td>38</td></tr><tr><td>Drilling</td><td>39</td></tr></table>
# SUMMARY

This document describes how to collect and prepare soil samples to monitor the soil organic Carbon and Nitrogen Stocks (CNS) within the target area of an EC flux tower. The stocks are calculated for the first meter (0 to 100 cm). The CNS will be determined from simultaneous measurements of soil organic carbon and nitrogen contents and bulk density. Whereas the C and N contents of soil samples are determined by the ETC central laboratory, the soil density must be measured by the station team.

This document is structured in different sections with the aim to facilitate the use and application:

- Objectives and Definitions

- Overview of the soil sampling activities

- Soil sampling: description of the methods available to collect samples according to soil characteristics (soil texture, structure, stoniness, root content)

- Sample processing: description of available methods for soil preparation (drying and sieving), measurement of physical parameters (water content and stoniness), compositing and reduction to constitute the laboratory and archive soil samples

- Calculation and data submission: description of the sample identification and shipping to the soil analysis laboratory and soil archive facility, data preparation and submission to the ETC. It includes the list of all the parameters, the correct formatting and the way to submit them to the database. It is linked to the BADM system needed to submit the metadata and non-continuous measurements.

- Maintenance of tools

It is important to remind that the exact application of the protocol at station level must be also discussed with ETC in order to reach agreed solutions for specific cases. If a specific part is relevant only for a specific ecosystem or station Class this is also reported in the document.

This Instruction document is based on the following ICOS Ecosystem protocols and documents:

- Saby et al., 2016 "Soil carbon stocks", ICOS ecosystem variable protocols

- Jolivet et al. 2016 "Volumetric sample for the determination of bulk density". In "Manual for the French soil monitoring network", version 1.1. Available upon request from INRA US 1106 InfoSol, infosol@inra.fr

- International Standard ISO-11074-2:1998 (Soil quality – Vocabulary – Part 2: terms and definitions relating to sampling)

- Kruger et al., 2016 "Calculating carbon changes in peat soils drained for forestry with four different profile-based methods", For Ecol Manag, 381, 29-36, 10.1016/j.foreco.2016.09.006.

- WRB IUSS Working Group WRB, 2015 "World Reference Base for Soil Resources 2014, update 2015, International soil classification system for naming soils and creating legends for soil maps". World Soil Resources Reports No. 106. FAO
**OBJECTIVES AND DEFINITIONS**

The soil is a major component of the terrestrial carbon cycle and monitoring the temporal changes in the soil carbon and nitrogen stocks is requested in order to close the ecosystem mass balance of these elements and to assess the role of terrestrial ecosystems in the global carbon cycle. This protocol describes how to collect and prepare soil samples to monitor the soil organic Carbon and Nitrogen stocks (CNS) within the target area of an EC flux tower. The SOC stocks are calculated for the first meter (0 to 100 cm) and will be determined from simultaneous measurements of soil organic carbon and nitrogen content and bulk density. Throughout this document the following definitions are being used:

**Sampling Point:** it is a point in the target area where sample collection will be operated. In ICOS guidelines, the soil sampling points correspond to SP-II and are defined by the ETC following the Instruction on Sampling Design.

**Individual sample:** sampling unit collected by a single operation of a sampling device and kept and treated separately from others.

**Composite sample:** two or more individual samples mixed together in appropriate proportions, from which the averaged value of a desired characteristic may be obtained.

**Aliquot:** known amount of a homogeneous material, assumed to be taken with negligible sampling error.

**Organic layers:** according to the World Reference Base for Soil Resources, the organic horizons “O” are dominated by organic material, consisting of undecomposed or partially decomposed litter, such as leaves, needles, twigs, moss, and lichens, which has accumulated on the surface; they may be on the surface of either mineral or organic soils, or at any depth below the surface if it was buried. O horizons are not saturated with water for prolonged periods. The mineral fraction of such material is only a small percentage of the volume of the material and generally is much less than half of the weight. The O horizons classification is as follows:

- slightly decomposed plant material (Oi) are almost entire leaves and twigs

- moderately decomposed plant material (Oe) are fragmented plant parts still identifiable as twigs, leaves, buds, etc.

- highly decomposed plant material (Oa): not identifiable.

The “H” horizons or layers are also organic layers dominated by organic material, formed from accumulations of undecomposed or partially decomposed organic material at the soil surface which may be underwater and are saturated with water for prolonged periods or were once saturated but are now artificially drained.
# SOIL SAMPLING OVERVIEW

To sample the relevant soil characteristics across the target area, the sampling strategy includes 20 discontinuous measurement plots (SP-I). Within each SP-I, a variable number (3 or 5) of sampling SP-II points are used for soil sampling. The Instructions for Sampling Design describes how these points are selected.

## Determine if sampling is needed

As a preliminary step it must be determined whether the detection of a temporal change in the soil carbon stock is feasible and the present instructions are applicable. As a rule of thumb, temporal changes of the total soil carbon stock over the next 20 years expected to be less than 20-25% of its spatial standard deviation are unlikely to be detected. This is mainly the case for soils where the carbon stock is huge as compared with its expected changes over 20 years, typically the peat soils. This may apply also for the soil having a relatively large spatial inhomogeneity due for instance to stoniness (e.g. forests soils on glacial deposits). In such cases, it is important to describe the soil in order to evaluate the feasibility of detecting a temporal change and decide together with ETC whether these instructions can be applied or an alternative approach found.

## Soil description

The first core or pit of each location at the SP-I points should be described by a soil expert or a properly trained staff. When the number of 20 cores or pits is not achievable because of e.g. difficulty of access, it can be reduced to ten or five after discussion with the ETC. The following data must be reported:

**WRB name:** (e.g., Albic Stagnic Luvisol (Cutanic, Endoclayic)) (see http://www.fao.org/3/a-i3794e.pdf)

**Horizons description:** each horizon of the profile must be described using the following variables:

- Upper and lower vertical limits of the horizon

- Colour of the horizon using the Munsell color code chart and the format as follows:

xxYY /vv cc (e.g., 10YR /3 4) where lower case are numbers and upper case letters coding for hue (xxYY), value (/vv) and chroma (cc) respectively. See for instance http://munsell.com/color-products/color-communications-products/environmental-color-communication/munsell-soil-color-charts/.

- Texture of the horizon (in Annex 1)

- Diagnostic horizon name (if applicable) according to the FAO WRB (http://www.fao.org/3/a-i3794e.pdf)
- Diagnostic material name (if applicable) according to the FAO WRB (http://www.fao.org/3/a-i3794e.pdf)

- Diagnostic property name (if applicable) according to the FAO WRB (http://www.fao.org/3/a-i3794e.pdf).

A picture of each pit or core showing the vertical profile of the entire soil from 0.0 to 1.0 m depth must be taken. A graduated scale must be put along the core or pit and must be visible in each picture. The upper and lower limits of the soil must be clearly identified when necessary. The picture should show the entire vertical profile of the soil so that the soil cores taken along the same profile must be reassembled accordingly. The pit wall chosen to be photographed must be well clean and lit, preferably by natural light (Figure 1).

<figure><img src="image_2.png" /><figcaption>Figure 1. Example of photo of the soil profile with scale</figcaption></figure>
**Measurement methods**

All the measurements and sampling are based on a set of standard depths measured from the surface of the mineral soil and specifically: 0-5; 5-15; 15-30; 30-60; 60-100 cm. O layers are sampled separately and their thickness recorded. For peat soils, the standard depths are the same but supplemental cores can be sampled until reaching the mineral layer.

The International Standard ISO-11272:1998 describes three methods for the determination of dry bulk density of soils calculated from the mass and the volume of a soil sample. All three methods involve drying and weighing a soil sample, the volume of which is known (core method) or has to be determined (excavation method and clod method). At each sampling point, a series of core samples of known volume must be extracted. The core method (i) must be used for non-stony and coherent soils and the excavation method (ii) for stony soils.

(i) In non-stony coherent soils, samples have to be taken as vertical undisturbed cores that are extracted with a motor hammer corer or a root corer. All five SP-II locations around each SP-I (n = 20 × 5) have to be sampled (Figure 2a). The core samples of known volume will be extracted from the layer depths defined above.

(ii) In stony or incoherent soils, only the first three SP-II locations around each SP-I have to be sampled (n = 20 × 3, Figure 2b). At each SP-II location, a soil pit is dug and individual volumetric samples are extracted in the pit from the layer depths defined above. Because volumetric samples thicker than 10 cm are practically difficult to extract in one piece, the layers 30-60 cm and 60-100cm are sampled by means of two superposed samples of equal volume. The individual volumetric samples are taken either by the cylinder method or the excavation method according to the International Standard ISO 11272:1998.

<figure><img src="image_3.png" /><figcaption>Figure 2. Soil sampling at each SP-I location, extracting either (a) 5 undisturbed vertical cores or (b) individual volumetric samples from 3 soil pits.</figcaption></figure>
**Timing of soil sampling**

The soil sampling should be carried out at a time when the conditions of humidity are close to the field capacity and in a stabilized ground, not recently ploughed, to ensure qualitative sampling. The ground water table should be below the soil depth to be sampled. In croplands, the sampling must be carried out at least four weeks after the last ploughing at a time when the upper soil layers are firm and wet and allows using a soil auger or automated corer. In addition, periods following cultivation operations (tillage, disking, seeding, fertilisers application etc.) must be avoided. The total duration of field operations can be estimated between 2 and 4 weeks depending on the number of staff and soil characteristics. It must not exceed three months. When several sampling teams are in charge of sampling they must be trained first together in order to achieve the best achievable comparability.
# SOIL SAMPLING PROCEDURE

For sampling soil and organic horizons the upper surface of the soil at the interface between "O" horizons and the upper mineral horizon must be carefully identified. Then, at each individual sampling location, the organic horizons O must be collected using a frame (25x25 cm²) and separated between the Oi, Oe, and Oa layers. Then, mineral soil cores can be taken from sampling depths 0-5, 5-15, 15-30, 30-60, 60-100 cm for organo-mineral and mineral horizons (see Figure 2). Whatever the technique used, it is essential to obtain for each sample collected i) the sample volume, V in cm3, ii) the sample vertical thickness, LT in cm, and iii) the sample horizontal cross sectional area, A. Cores have to be typically about 10 cm in diameter. The size of the pits has to be adapted to local conditions and in any case kept as small as possible. If core sampling is impossible to achieve (i.e., randomly distributed stones in depth) it is recommended to try to reach at least a depth of 30 cm by resampling once 1 m away from the theoretical point. In case a depth 30 cm can again not be reached, the deepest sampling point will be retained, and the soil depth will be considered to have been reached. For cores deeper than 30 cm, any impossibility to dig down to a depth less than 1 m, i.e. because of shallower bedrock, will define the soil depth. In case the soil depth is in between the standard depth values (e.g. it was possible to arrive to 55 cm, in between the standard range 30-60 cm) the layer between the upper standard depth and the soil depth has to be taken (e.g. 30-55 cm is considered as last layer instead of 30-60 and 60-100). Pits have to be re-filled after digging, respecting the vertical order of layers.

Because of the numerous samples and to ensure a precise identification, it is mandatory to use special plastic bags with pre-printed forms that will be provided by the ETC, and to label them carefully according to the following examples. The identification code for each soil sample will be as follows:

## CC-SSS_YYYYMMDD_S1-S2_UD_LD

where CC-SSS is the ICOS station code, YYYYMMDD is the sampling date, S1-S2 is the SP-II identification number as defined in the PLOT_ID (e.g. 01-01, see ICOS BADM on Sampling scheme) and UD and LD are respectively the upper and lower depths in cm. The identification code has to be reported on the label on the bag and duplicated on a plastic label to be inserted inside each plastic bag for avoiding mistakes. Additional information such as the name of the person collecting the sample, type of sample, sampling method and sample volume, thickness and area must be recorded and subsequently transferred to the ETC.

Also organic horizons samples must be collected in the same plastic bags and in the identification code UD is substituted by the name of the horizon (O, or eventually Oi, Oe and Oa when appropriate) while LD will have to report the thickness of the horizon collected in cm.

## CC-SSS_YYYYMMDD_S1-S2_XX_LT

where XX stands for Oi, Oe or Oa and LT for the layer thickness (cm).
Before extracting the core from the auger or starting to sample from the pit, a picture of each soil core or pit must be taken, with the site code, date and location in the name (e.g. FR-Bil_20161202_01-03.jpg).

**Equipment**

**Generic equipment**

- Shovel, spade, pickaxe, moil

- Knife, Berthelet trowel

- Spatula and trowels

- Pruning shears, scissors, handsaw (to cut the roots)

- Folding rule

- Labels, elastics, pencils, markers, paper labels

- 500 to 800 Plastic bags (provided by ETC) for field collection. The exact number of bags requested depends on the sampling scheme and the presence of organic layers.

- Portable field scale with 0.5g precision.

**Specific equipment for the frame technique**

- Metallic square frame with 25 x 25 cm inner dimensions and equipped with two 10 cm long iron rods for plugging.

**Specific equipment for the cylinder technique**

- Steel cylinders or rings (with an inner volume of approximately 500 cm³) with one sharpened edge (home-made or commercially available, see for instance at https://en.eijkelkamp.com). The cylinder dimensions can be adapted to the thickness of the layers.

- Hitting plate or cylinder

- Small plate to place the cylinder on

- Small and large mallet

**Specific equipment for the water technique**

- Spirit level (20 cm) to verify the flatness of the prepared surface

- Annular template of inner diameter long enough to take at least a 1000 cm³ sample

- Nails to fix the annular template

- Tablespoon, ladle, paintbrush

- Clear, thin and robust plastics bags
- 500 ml measuring cylinder graduated by 5 ml

- 5 litres of water

- Funnel

**<u>Specific equipment for the sand technique</u>**

- Graded sand with sand size particles between 500 and 700 µm

**The manual frame method (organic and uppermost soil layer)**

This method is compulsory for organic horizons and recommended for the upper mineral layer (0-5cm) as it is difficult to core precisely the surface horizons particularly with crumb or granular structures. It is based on the collection of a volumetric sample by excavating the organic layer or soil within a square frame, and in a given thickness. The volume extracted can be calculated from the dimensions of the cavity (frame area x thickness). As the difficulty of maintaining a proper geometrical shape can alter the precision of the method, the use of a large frame of at least 25 x 25 cm is recommended. The depth of the dug out cavity is measured in order to allow volume calculation.

**<u>Step-by-step operation mode</u>**

1. Sampling is realized directly from the soil surface. Install the frame on the soil by pushing the two iron rods in the ground (Figure 3A).

2. Collect the O layers on the whole frame surface and throughout their entire thickness. Use a knife to cut the sample along the inner edges of the frame and collect the material with a hand spade or spoon. Put the material in a labelled sample bag and insert a plastic label with sample identification code inside. All vegetation debris inside the frame must be collected (Figure 3B).

3. Measure the thickness of the cavity (mean from 5 to 10 measurements in case of irregular depth) and note it on the sample bag and on the field report (Figure 3C).

4. For the 0-5 cm layer, proceed in the same way by collecting the soil layer on the whole frame surface, using a knife to cut the sample along the inner edges of the frame (Figure 3D).
<figure><img src="image_4.png" /><figcaption>Figure 3. steps of the manual frame technique for organic and uppermost soil layer sampling. A: frame installation; B: organic layer sampling; C: organic layer thickness measurement; D: first soil layer sampling.</figcaption></figure>

## The “Core” method with mechanical sampling (motor hammer corer)

Mechanical sampling can be used for coring the mineral part of the soil (after removal of the organic layer as seen previously). The Annex 1 of this document presents the different systems: Jack hammer or drillers, and a method to extract the gouge from the soil. The soil coring must be operated at the same location than organic layers sampling. The corer must be driven vertically.

### Soil sample preparation in the field

Once the gouge is extracted, in order to avoid errors due to soil compaction, measure the soil depth and the depth of the gouge (Figure 4A) and note them a logbook, then carry the gouge to a “soil preparation spot” (Figure 4B), where you have prepared the labels, aluminum trays and a knife. At the soil preparation spot arrange the trays and plastic labels in the necessary order, open the window of the gouge (Figure 4C) and measure the length of the soil core (Figure 4D) taking note of it.

<figure><img src="image_5.png" /><figcaption>Figure 4. Soil sample preparation with “Core” method. A: measure the depth of the gouge; B: organize a soil preparation spot with all the material needed; C: open the window of the gouge; D: measure the length of the soil core.</figcaption></figure>
Cut the soil column into the predefined slices (0-5, 5-15, 15-30, 30-60 and 60-100 cm) (Figure 5A) and transfer the soil slices into the corresponding trays (Figure 5B). Once the whole soil column is emptied, crumble and dissect the soil in order to disaggregate the soil aggregates (Figure 5C). Put the soil into the ICOS plastic bag properly labeled, insert its plastic label inside repeating the sample identification code, close the bag evacuating the air inside as much as possible and store the plastic bag for the transport to the lab. In case a scale can be used in the field, weight the fresh soil sample. Otherwise the weighing must be done within 5 days after bringing the samples back in a cold chamber between 4 and 10°C. At this stage, the soil sample volume (V) and fresh weight (W0T) must have been determined.

<figure><img src="image_6.png" /></figure>

Figure 5. Soil sample preparation with “Core” method. A: cut the soil column at the predefined depths using a home made slicer in this case; B: transfer soil slices into the corresponding trays; C: crumble and dissect the soil.

## The “Core” method with semi-mechanical sampling (root corer)

The use of a root corer (Figure 6A) could be an alternative to the use of the motor hammer corer described above. Typically, such a corer is provided with a sampling cylinder of 15 cm length and a diameter of 8 cm that is a volume of about 750 cm³. The corer is driven vertically in the soil either by manual rotation or by percussion using a mallet, the latter being useful in the compact horizons. The crank is used to remove the sample from the cylinder. The handle of the corer is graduated each 15 cm to check the depth of sampling.

The root corer can be easily used to sample the 5-15 cm layer (one 10 cm long core), the 15-30 cm layer (one 15 cm long core), the 30-60 cm layer (two successive 15 cm long cores), and the 60-100 cm layer (three successive cores: 15, 15 and 10 cm long). The sample preparation is the same explained for the mechanical sampling apart from the extraction of the sample from the corer that is done using the crank (Figure 6B).
<figure><img src="image_7.png" /><figcaption>Figure 6. Soil sample preparation with “Core” method using a root corer (A). B: extraction of the sample</figcaption></figure>

**Excavation method (cylinder, water and sand techniques)**

Three excavation techniques dedicated to soil pits are described here: the cylinder technique, the water technique and the sand technique. For organo-mineral and mineral layers, the most appropriate technique will be selected according to the soil characteristics (consistency and thickness of the soil layer, stones and roots contents).

The water and sand techniques must be used when the cylinder technique is difficult to use: in the presence of gravels, pebbles and roots, or in the very clayey horizons. These techniques are not suited to sample small volumes. The main difficulty of the water technique is to obtain a soil surface flat enough to fit exactly the water level to the surface of the ground. That is why for soil on steep slopes, the sand technique is more suitable.

**Cylinder technique**

The cylinder technique allows collecting undisturbed volumetric samples of predetermined volume. This technique is described according to the ISO 11272:1998 International Standard. It is suited for soils with a small content of stones, gravels and roots. Large steel cylinders are recommended (500 cm³ e.g. 8.4 cm inner diameter × 9 cm height) to allow extraction of large volumes and minimize relative errors. Small cylinders (250 cm³ e.g. 8.4 cm inner diameter × 4.5 cm height or 100 cm³ e.g. 5.3 cm inner diameter × 4.5 cm height) can be used to characterize the thinner soil layers (5-15 cm and 15-30 cm). It is not recommended to use cylinders with diameter larger than 10 cm unless the soil is particularly plastic and coherent. In addition, cylinders with height larger than 10 cm must also be avoided wherein removing the sample from the soil matrix can be very difficult. For thick soil layers e.g. 30-60 cm and 60-100 cm, it is necessary therefore to take several samples superposed to cover the whole layer thickness. As shown in Figure 2b, one soil sample must be taken for each depth level sampled from 5 to 30 cm (i.e. 5-15 cm and 15-30 cm), two superposed for the 30-60 cm level and three superposed for the 60-100 cm level.
**Step-by-step operation mode**

Sampling is realized from the soil surface for the uppermost sampling depth (Figure 7A) and from stair-stepped surfaces in the soil pit for the deeper sampling depths (Figure 8C). Horizontal surfaces are shaped by using the trowel or the Berthelet trowel. The cylinder (Figure 7B) is hammered vertically in the soil using one or two mallets on the hitting plate (an aluminum half cylinder in Figure 7C). Gently remove the cylinder from the soil by means of a knife, a spatula or a trowel digging out the soil all around the cylinder. Cut the soil below the cylinder's underside with a well sharpened knife and insert a spatula below the cylinder and remove the cylinder + spatula, ensuring that no soil falls out of the cylinder (Figure 7D).

<figure><img src="image_8.png" /><figcaption>Figure 7. Cylinder technique phases: A) prepare the surface and the cylinder (B), C) hammer the cylinder vertically in the soil and then extract it (D).</figcaption></figure>

Once extracted, place the cylinder on the plate and carefully level both sides of the cylinder with a knife (Figure 8A-B). Empty the cylinder in the labelled sample bag adding the plastic label inside. Remember to measure the sampling depths of the cylinder (top and bottom) and note them on the sample bag and on the field report.

<figure><img src="image_9.png" /><figcaption>Figure 8. Cylinder technique phases: A and B preparation of the sample in the cylinder; C: stair-stepped surfaces in the soil pit.</figcaption></figure>

**Note:** driving the cylinder vertically is recommended but driving it horizontally through the pit wall is allowed, particularly in deep horizons.
## Water and Sand techniques

The water technique and the sand technique allow both to collect volumetric samples of varying volume by excavating soil and measuring the volume of the cavity with either water or graded sand poured into in the cavity covered by a plastic film. The water technique is adapted from the standard sand technique (ISO 11272:1998) by replacing the graded sand with water. The stonier the soil and the larger the pebbles (stones or blocks), the more important is the volume of the cavity. So to improve the precision of the measurement, it is recommended to collect samples of more than 2000 cm³.

## Step-by-step operation mode

Sampling is realized from the soil surface or in the deep horizons of a pit, by fitting stair-stepped surfaces (Figure 9A). Horizontal surfaces are shaped by using the trowel or the Berthelet trowel. A perfect leveling is needed so place the annular template on the soil surface, fix it with the nails and check the leveling with the level (Figure 9B). Start to dig a cavity at the center of the annular template with a knife, a table spoon and a ladle, according to the wetness of the soil. The diameter of the cavity has to correspond to the annular template and the depth of the cavity must be adjusted according to the thickness of the layer to sample. All of the extracted earth must be collected in the labelled sample bag with the corresponding plastic label inside (Figure 9C). The extracted earth must be extracted without losses (collect the possible losses fallen on the template and the small aggregates remaining at the bottom of the cavity by means of the paintbrush). Be sure take at least a 1000 cm³ sample. The shape of the cavity does not need to be a perfect cylinder but its walls must be as regular as possible: avoid recesses and projections of sharp stones or roots susceptible to drill the thin bag used to coat the cavity. When a sufficient amount of soil is sampled, place the thin bag in the cavity and stick it onto the walls (Figure 9D).

<figure><img src="image_10.png" /><figcaption>Figure 9. Water technique. A) prepare the stair-stepped surface; B) place the annular template perfectly horizontal; C) sample the soil using a spoon and a ladle; D) place the thin bag in the cavity.</figcaption></figure>

Fill the bag with water (Figure 10A) by using a measuring cylinder until the exact surface level of the cavity is reached (Figure 10B). Check that the plastic film adheres well to the walls of the cavity by rectifying the adhesion by means of the spoon. The volume of extracted soil corresponds to the total
volume of water poured into the cavity. Note the measured volume of the cavity on the sample bag and in the field report. Measure also the sampling depths of the cavity (top and bottom) and note them on the sample bag and in the field report (Figure 10C).

In the sand technique, the water is replaced by the graded sand, which is used to measure the volume of the cavity. This technique is described in the International standard ISO 11272:1998.

<figure><img src="image_11.png" /><figcaption>Figure 10. Water technique. A) fill in the cavity with water; B) measure the total volume of water poured into the cavity; C) measure the depth of the cavity; D) multiple cavities can be used.</figcaption></figure>

**Special instructions for peat soils**

Acknowledging that the assessment of temporal changes in the total C and N stocks in virgin mires using repeated measurements based on cores is not achievable and that the carbon export by lateral fluxes is a major component of carbon balance of mires, it can be proposed to the ETC to not apply the sampling scheme described in this document in these sites.

Either alternative method can be proposed, especially in actively drained peatlands and shallow peat soils where temporal changes might be significant and detectable, or the determination of the temporal changes of C and N stock simply ignored. Since the main objective of the soil sampling strategy is to close the ecosystem mass balance of carbon, the alternative method proposed should consider also to determine the discharge fluxes of carbon and nitrogen.

However it remains compulsory in all sites to sample the soil peat down to its lower limit that is its transition with the mineral subsoil, as far as this is technically feasible. Sampling must be carried out at a total of 5 to 10 points among SP-I locations in order to provide an overall estimate of the total carbon and nitrogen stocks and a general description of the peat vertical profile as part of the general site description.

In case the cores are sampled deeper than 1 m, the portion until 1 m must follow the standard layer sizes (0-5, 5-15, 15-30, 30-60, 60-100 cm), while the part exceeding 1 m is sampled in layers of 50 cm (e.g. 100-150, 150-200, 200-250 cm etc.).

To collect the samples in peat, it is recommended to use a corer adapted for these ecosystem such as the Wardenaar corer (Figure 11), an apparatus for sampling intact, undisturbed peat profiles in peat
lands up to a depth of 1 meter. The peat profile sampler consists of a rectangular stainless steel box casing, divided lengthwise into two halves, with very sharp specially shaped cutting edges at the base. The handgrip hinging with both halves allows both halves to be pushed into the soil alternatingly. A clamp mechanism on the grip allows the profile to be clamped in the sampler when it is extracted from the soil. Then, in the field, the peat core is cut with a sharpened blade and scissors to obtain samples at the required depths (0-5, 5-15, 15-30 cm, etc.). If the peat layer thickness is less than 1.0 m, the Wardenaar corer can be used down to this depth and a standard corer can be used for collecting soil samples at deeper levels.

<figure><img src="image_12.png" /><figcaption>Figure 11. the Wardenaar corer designed to sample peat profiles</figcaption></figure>
# SAMPLE PROCESSING

The sample processing describes the operating modes to obtain the composite samples that will be sent for chemical analysis and archiving and the instructions for the bulk density determination. The following operating modes are adapted from the International Standard ISO-11464:1994. Please refer to this document for further details. All the used equipment must be clean and dry, the worktop must be cleaned each time a sample has been processed to avoid cross contamination between samples. Every sample must be clearly and precisely identified at each step of the sample processing.

## Equipment

- Latex gloves

- Plastic trays (typically 25 x 25 cm), about one or two for each sample

- Sieve with 2mm mesh size with round holes

- Porcelain pestle and mortar

- Pinch tweezers for roots manual removal

- Metallic containers for stones/gravel and roots

- Flat circular plate with removable vertical sides (type springform pan)

- Small plastic shovel

- Knife blade

- Ventilated oven with temperature control (70 and 105°C)

- Drying room (~30°C and 30% of humidity) [optional]

- 100 to 160 additional plastic bags (provided by ETC) for shipment. The exact number of bags requested depends on the sampling scheme and the presence of organic layers.

- 160 plastic containers of 500 cm³ for sample packaging for C and N analysis. Example of recommended containers: https://www.grosseron.com/flacon-carre-a-large-ouverture-simple-et-double-fermeture-cape-jointee_48-132-1-317-1-748.html

- Precision electronic balances (0-2000g with <0.01g error and 0-200g with <0.001g error)

- Large desiccators (20 dm³) with dry silica gel

- Grinder or crusher or knife - or ball mills for organic material
Mineral soil samples

The mineral soil samples preparation and processing can be divided in 3 main steps that are described here below and summarized in Figure 16.

Step 1 - Drying and sieving each individual sample to obtain fine earth, stones and root mass values

The following processing should be applied on each individual sample: use this method for all the samples of each soil layer.

1. Weigh the moist field sample, either in the field or in the laboratory with the precision balance (WOT).

2. Dry the soil in a heating chamber or a drying room at 30°C ± 5°C. To do this prepare the plastic trays to spread samples. Verify the cleanliness of the trays. Stick on every tray the identifiers of the sample (Figure 12A), to be able to recognize it unequivocally during the following steps, by writing on a label stuck on the front of the tray with the following information:

- [the identifier of the sample] as CC-SSS_YYYYMMDD_S1-S2_UD_LD (see Soil Sampling Procedure section above)

- [the tray number (n/nt)], nt is the total number of trays for a single soil sample. Optional when nt =1.

With latex gloves on, spread the samples in the trays, ensuring a good mixing of the sample at this stage (Figure 12B). Every sample is distributed in a sufficient number of trays to allow fast drying: clumps of earth are to be reduced to small aggregates before spreading them in a thin layer not thicker than 20 to 25 mm. Depending on the soil texture, the drying time takes between 5 to 10 days, until a constant weight is reached.

3. Use the precision balance to weigh the sample after drying, paying attention to weigh all the trays for each sample and to subtract the weight of the trays.

4. Sample sieving at 2mm mesh

- **Crushing.** The crushing step is requested depending on the soil sample structure. It consists in breaking the aggregates and in separating the coarse elements (stones and concretions) of the fine earth by means of a porcelain mortar and pestle. Soil clumps or aggregates are manually disintegrated without grinding the elements like concretions. Be careful in the case breakable elements as concretions or pieces of limestone are present in the sample, as these should not be grinded.

- **Sieving.** The loosened earth is then sieved through a 2mm mesh size sieve. Stones, gravels and roots constitute the refusal > 2 mm (residue on the top sieve). They are removed manually with the pinch tweezers (Figure 12C) and put aside in metallic containers for weighing (coarse elements) and further drying (roots). The sieving is
finished when the refusal elements are clean; a criterion to judge sufficient sieving is
-to check the colour of the face of the stones (Figure 12D).

5. Weighing of fine earth, stones and roots

5.a Weigh the fraction of fine earth (W30E) as well as the fraction of coarse elements (W30S) using a precision balance.

5.b The roots fraction must first be further dried at 70 °C before weighing (see box 1 below). Drying must be done in a ventilated, temperature-controlled oven until a constant weight is reached. For sake of practicality, the required drying duration can be determined prior to the experiment, it is typically 48 or 72 hours. The temperature of the oven should be controlled by a calibrated sensor and kept constant at the target temperature ±1°C.

Determine the dry weight using a precision balance (W70R respectively, see box below).

<figure><img src="image_13.png" /><figcaption>Figure 12. Sample preparation. A) drying the sample; B) loosening the sample; C) remove stones and roots; D) fine earth.</figcaption></figure>

**BOX 1. Drying and weighing procedure**

This procedure must be applied for drying and weighing soil mineral and organic samples at a given
temperature. Drying at 30 ±5 °C can be operated in a well ventilated room. Drying of samples at
70°C or 105°C must be done in a ventilated, temperature-controlled oven until a constant weight is
reached. For sake of practicality, the duration requested to reach a constant weight can be
determined prior to the experiment, typically 48 or 72 hours. The temperature of the oven should
be controlled by a calibrated sensor and kept constant at the target temperature ±1°C.

After drying, the samples must be taken from the oven into a desiccator filled with dry silica gel for cooling down to room temperature while avoiding the re-humidification of the sample. Alternatively, soil samples may be left cooling down in the oven closed providing a sufficient volume of fresh silica gel has been placed inside the oven for avoiding the sample to rehumidify. Each sample is then weighed to the nearest 0.01 g. Dry weight uncertainty is calculated using the uncertainty of the scales used to perform the weighing. The uncertainty of the scales is given by the accredited company that verifies them once a year.
At the end of this step of the operating mode one should obtain for each individual sample:

- the weight of fine earth, **W30E**

- the weight of coarse elements (stones and gravels), **W30S**

- the weight of roots, **W70R**

## Step 2 – Combining fine earth of individual samples to obtain a composite sample

The composite sample is a representative sample obtained by mixing the 5 (or 3) fine earth samples of the same layer and SP-I location. This step is thus repeated for each mineral soil layer (0-5, 5-15, 15-30, 30-60, 60-100) at each of the SP-I locations (n=20).

First, the proportion of each individual sample in the composite sample is calculated using the apparent density of each sample:

$$Q_{i,l,s} = \frac{WA30E_{i,l,s}}{SUMWA_{l,s}}$$

where

- $Q_{i,l,s}$ is the proportion of soil dried at 30 °C to be used from the sample i (i=1 to 3 for pits or 1 to 5 for cores), layer l (l = 0-5, 5-15, 15-30, 30-60, 60-100), SP-I location s (s = 1 to 20)

- $SUMWA_{l,s}$ is the sum of the mass of fine earth ($WA30E_i$) of all the samples to combine for the layer l and the SP-I location s (in kg m⁻²).

- $WA30E_{i,l,s}$ is the mass of fine earth of sample i per unit area (in kg m⁻²).

The mass of fine earth per unit area for each sample can be calculated as:

$$WA30E_{i,l,s} = LT_{i,l,s} \times \frac{W30E_{i,l,s}}{V_{i,l,s}} \times 10$$

where $W30E_{i,l,s}$ is the mass of fine earth of the sample (in g), $LT_{i,l,s}$ is the sample thickness in cm, and $V_{i,l,s}$ is the volume of the sample in cm³. The layer thickness may vary among samples with excavation methods. The mass requested from each individual soil sample, $QE_{i,l,s}$ (in g) is given as:

$$QE_{i,l,s} = Q_{i,l,s} \times TW_{l,s}$$

where $TW_{l,s}$ is the target weight (in g) of the final composed sample for layer l, SP-I location s (1500-2000 g). An Excel file that allows the calculation of the mass needed from each individual sample is provided by the ETC.

Second, the mass requested of each individual soil sample, is obtained with the quartering method. This method reduces the mass of a soil sample without introducing a sample bias and is based on a series of sub-sampling (Figure 13):
1) Using a flat circular plate with removable vertical sides, spread the sample mass in order to form a circular and uniformly flat "pie" over the bottom area. The surface should be dry and clean with enough space;

2) Divide the pie in 4 quarters of the same size by drawing 2 perpendiculars with a knife blade;

3) Remove two opposite quarters. The remaining mass will be about half the original mass;

4) If the remaining soil mass is more than the double of the calculated required mass for the composite sample, $QE_{i,l,s}$, repeat the previous step: homogenise the remaining fine earth sample, on the circular plate and remove this time the alternate opposing quarters;

5) Repeat the previous steps again in the presented order until the remaining mass is less than the double of the calculated required mass. The number of repetitions of the quartering method that is needed can easily be determined in advance.

<figure><img src="image_14.png" /><figcaption>Figure 13. Quartering method to reduce the mass of a soil sample. Homogenise the soil in a circular plate and split it in 4 quarters (Step1 A); Remove two opposite quarters (Step1 B). If the soil mass is still more than double the needed amount homogenise is again (Step2 C) and remove the alternate quarters (Step2 D). Continue with the sequence (Step3 and so on) until the desired mass is almost reached.</figcaption></figure>

The final mass of each sample obtained with the quartering method will be probably close to the requested amount but not the exact amount. In order to reduce it to the exact value $QE_{i,l,s}$, put the well mixed sample in a plastic container on an electronic balance and remove soil with a spatula until the target mass value is reached.

The obtained required quantities of the 5 (or 3) individual samples of the same SP-I location and soil layer, are then combined and mixed thoroughly to create the composite sample for the SP-I location $s$, and depth $l$. Each composite sample will have a minimum dry mass of 1500g.

### Step 3 – Extracting three aliquots from the composite samples

The obtained composite samples (one for each SP-I location and layer) must be split in three aliquots:

1) a 50±10 g aliquot for determination of bulk density. This aliquot must be weighed (WX30E), then dried at 105°C following the procedure described in Box 1, and then weighed again (WX105E) to calculate the residual humidity and the fine earth mass.
2) a 300±30 g aliquot that must be send to the Central Soil Analysis Laboratory (CSAL) for C, N and residual water content analyses; packaged in a 500 cm³ plastic container (Figure 14 left)

3) The remaining sample (not exceeding 1700g) that must be sent to INRA Orléans for archiving in the ETC Archive (European Conservatory of Soil Samples), packaged in plastic bag provided by the ETC (Figure 14 right)

<figure><img src="image_15.png" /><figcaption>Figure 14. Example of plastic containers for the sample sent to the CSAL (left) and plastic bags for the soil to be sent to the archive (right)</figcaption></figure>

The splitting of the composite sample in the three aliquots must be done following the following steps 1-6:

1) Divide the composite sample (1500-2000g) into 4 trays;

2) Take a sample with the plastic small shovel along the diagonal of each of the 4 trays and put these 4 samples in a new clean and dry tray (Figure 15);

3) Mix the composed sample in the new tray in order to create a homogeneous sub-sample;

4) If the obtained quantity is not sufficient, homogenise the remaining earth in each of the original 4 trays again and use the shovel again to take additional samples, this time along the opposite diagonal.

5) If needed, repeat the previous step until the requested amount is reached.

6) Finally, use a precision balance to obtain the exact amount of the 50 g and 300 g aliquot.
<figure><img src="image_16.png" /><figcaption>Figure 15. Splitting of the composite sample. The 4 trays with earth and sampled along the diagonal (top of the photo) and the samples put in a new clear and dry tray (bottom of the photo)</figcaption></figure>
<figure><img src="image_17.png" /></figure>

**Figure 16.** Scheme of the preparation and processing of mineral soil samples. For details on the different steps refer to the text.
## Organic samples

The organic samples preparation and processing can be divided in 2 main steps that are described here below and summarized in Figure 17.

### Step 1 - Drying and crushing samples

The following processing should be applied on each individual sample: use this method for all the samples of each organic layer (3 to 5 samples according to the sampling method).

1) Weighing of moist field sample either in the field or in the laboratory (WOO).

2) Removal of mosses and other living plant material

3) Drying at room temperature that is 30±5°C. Proceed in the same way as for organo-mineral and mineral samples. Use plastic trays to spread the samples in a thin layer and clearly identify the samples with labels. The drying time could be between 2 to 5 days, until reaching a constant mass.

4) Weighing of dried sample (W300).

5) Crushing of sample to obtain fine material (< 2mm). This may be done using either a knife mill or balls mill or a mortar and pestle as long as no contamination from the instrument is guaranteed.

6) Dry the crushed sample in a ventilated drying oven at 70°C following the same procedure described in Box 1.

7) Weigh the sample again (W700).

### Step 2 - Composite sample and aliquots extraction

Combine the fine material from individual samples to obtain a composite sample of the holorganic soil layers, Oi, Oa, Oe, at each of the 20 SP-I locations, following the same method described for organo-mineral and mineral samples. The calculation of the exact proportions of fine material of each individual sample to be composed must follow the same scheme described in Step 2 of the mineral soil. Use the "frame method table" of the excel sheet.

Use then the dividing method explained in Step 3 of the mineral soil to create the following aliquots from the composite sample:

1) a 300 g aliquot that must be sent to the Central Soil Analysis Laboratory (CSAL) for C, N and residual water content analyses, packaged in a 500 cm³ plastic container (Figure 14 left).

2) The remaining sample (not exceeding 1700g) that must be sent to INRA Orléans for archiving in the ETC Archive (European Conservatory of Soil Samples) packaged in plastic bag provided by the ETC (Figure 14 right).
In case the holorganic soil layers are very thin and the available fine material after preparation is less than 300g, send all the available sample to the Central Soil Analysis Laboratory (CSAL).

<figure><img src="image_18.png" /><figcaption>Figure 17. Scheme of the preparation and processing of organic samples. For details on the different steps refer to the text.</figcaption></figure>
**MAINTENANCE OF TOOLS**

The calibration and uncertainty of the scales used for weighing the soil and organic horizons samples is given by the accredited companies that should verify them once a year.

The thermometer used for oven temperature control must be calibrated by a certified organism to the nearest 0.5°C.
# DATA SUBMISSION

## Soil sample packaging for laboratory analysis

Each sample must be put into a plastic container with a screw-on cap and duly labelled twice with the sample identifier shown below: once using a sticker to be put on the container side and second with a paper label to be placed inside the container. Great care must be taken to mark each unit clearly before sending it to the CSAL. The identification sample code to be used must follow the scheme:

CC-SSS_YYYYMMDD_S1_UD_LD

where CC-SSS is the ICOS station code, YYYYMMDD is the sampling date, S1 is the SP-I identification number as defined in the PLOT_ID (e.g. 01, see ICOS BADM on Sampling scheme) and UD and LD are respectively the upper and lower depths in cm. For the organic horizons UD is substituted by the name of the horizon (O, or eventually Oi, Oe and Oa when appropriate) while LD will have to report the thickness of the horizon collected in cm. Samples must be packed and the carefully labelled otherwise can not be processed.

### Example:

Labels for the samples collected at the SP-I point 05 of the FR-Bil station on December 1st 2016 and where there are two organic horizon Oi and Oa respectively 2 and 3 cm thick plus the standard 5 depths in mineral soil will be:

FR-Bil_20161201_05_Oi_2

FR-Bil_20161201_05_Oa_3

FR-Bil_20161201_05_0_5

FR-Bil_20161201_05_5_15

FR-Bil_20161201_05_15_30

FR-Bil_20161201_05_30_60

FR-Bil_20161201_05_60_100

Altogether, for a station with 3 organic layers (Oi, Oe, Oa) and 5 mineral soil layers, a total of [3 + 5] × 20 SP-I = 160 samples should be sent for analysis. Samples should be grouped in a single parcel and sent to the Central Soil Analysis Laboratory (CSAL) of the ETC to the following address:

INRA- Laboratoire d'Analyse des Sols
ETC Central Laboratory
273 rue de Cambrai
62000 ARRAS
France
## Soil sample packaging for archiving

The same procedure is applied as above. Each sample must be put into a plastic bag, hermetically closed, and duly labelled twice with the sample identifier shown in Table 1: first using a permanent black marker on the bag itself and second with a plastic label to be placed inside the bag.

<table><caption>Table 1. Example of data to be put on each plastic bag for archiving.</caption><tr><td>DATE OF SAMPLING</td><td>20161201</td></tr><tr><td>SAMPLER'S NAME</td><td>Kirk DOUGLAS, Marlene DIETRICH</td></tr><tr><td>SAMPLE TYPE</td><td>Mineral / Organic</td></tr><tr><td>SAMPLE IDENTIFICATION</td><td>FR-Bil_20161201_01_5_15</td></tr><tr><td>SAMPLING METHOD</td><td>Soil corer (diam = 10 cm)</td></tr><tr><td>MIN and MAX DEPTHS OS SAMPLING (cm)</td><td>5-15</td></tr><tr><td>SAMPLE VOLUME (cm³)</td><td>785.4</td></tr><tr><td>ICOS STATION IDENTIFIER</td><td>FR-Bil</td></tr></table>

Great care must be taken to mark each unit clearly before sending it to the Central Soil Archive that is the ESSC (European Soil Samples Conservatory in Orléans). The identification rule to be used is the same as for the samples for the analysis:

CC-SSS_YYYYMMDD_S1_UD_LD

where CC-SSS is the ICOS station code, YYYYMMDD is the sampling date, S1 is the SP-I identification number as defined in the PLOT_ID (e.g. 01, see ICOS BADM on Sampling scheme) and UD and LD are respectively the upper and lower depths in cm. For the organic horizons UD is substituted by the name of the horizon (O, or eventually Oi, Oe and Oa when appropriate) while LD will have to report the thickness of the horizon collected in cm.

Also in this case altogether up to 160 samples should be sent for archiving for each sampling date. Samples should be grouped in a single parcel, sent by any surface transporter avoiding the public French Poste Office (Colissimo) to the ESSC at the following address:

INRA - Conservatoire Européen des Echantillons de Sol
ICOS-ETC
2163 avenue de la Pomme de pin
CS 40001 Ardon
45075 Orléans Cedex 2
France
**Data submission**

All the data and information needed to correctly process and document the samples shipped to the ETC must be submitted using the BADM system (SOSM group). Data and metadata cover information about the method used, the sample type, size, position and all the different weights measured. All these are needed to identify and characterize each sample shipped.

All the metadata are mandatory and needed before the samples analysis and for this reason must be submitted as soon as the samples are ready to the shipped. Without metadata the analysis can not be done.
# ANNEX 1: SOIL TEXTURE CLASSES

Classes according to Annex 4 of the “World Reference Base for Soil Resources 2014”, p 192

## Soil particle-size and texture classes

Relation of constituents of fine earth by size, defining textural classes and sand subclasses

<figure><img src="image_19.png" /></figure>

Source: Adapted from FAO (2006): Guidelines for Soil Description
# ANNEX 2: MOTOR SAMPLING SYSTEM

(from *Mode opératoire* for soil sampling, INRA, Clermont-Ferrand. K. Klumpp et al.)

## Sampling and drilling systems

<figure><img src="image_20.png" /><figcaption>Figure A1. A: Percussion hammer Cobra TT powered; B: Percussion /jack hammer with gasoline; C: Hydraulic soil corer</figcaption></figure>

## Material

For more information see description of Eijkelkamp.com.

- Tripod or squad / pickup with adapted fixation to lift the jackhammer to the necessary height

- Hoist/winch with chains to fix jackhammer

- Percussion /jack hammer with gasoline or powered percussion hammer Cobra TT

- rod puller extension for the extraction

- lifting jack with lever and chain

- stairs to be at working height

- Percussion gouges (combination type for various types of soil) in sufficient diameter (e.g. larger than 5 cm) and length (100cm). See examples in Figure A2.

Make sure your gouges have a window to close in order to determine bulk density, and a cutting end at the bottom to go through root and stones. Some coring system may alternatively be equipped with a thin-walled, disposable transparent liner that is put inside the core before digging, and thereafter extracted once filled with soil sample. The corer is loaded from one end with a new liner which is firmly fixed before every drill. After coring, the liner with the core (see Figure A2) is taken out afterwards. Systems exist from various manufacturers in various thicknesses including near and above 10 cm liner diameter e.g. www.roehren-hamm.de, www.geoprobe.com.
<figure><img src="image_21.png" /><figcaption>Figure A2. Examples of gouges</figcaption></figure>

## Methods

There are different ways to drill, either without uses of any accessories to facilitate the work and lighten the weight of the used material (see Figure A3) or by uses of a hydraulic system. Using the more simple version, there are two types of percussion hammer, depending on the number of points to sample, ecosystem (i.e. forest, arable, grass, etc.) and soil texture (i.e. stones, ...):

- The light electrical percussion hammer has a beating power of 31.7 Joule at 1200 beats per minute, a net weight of 17 kg and an overall length of 613 mm. The sound power level acc. to 84/537/EEC is not more than 108 dB (A).

- The heavy model has a beating power of 55.3 Joule at 1000 beats per minute, a net weight of 29.1 kg and an overall length of 825 mm. The sound power level is not more than 108 dB (A).

Using these hammers there are no petrol vapors and exhaust gasses directly over the sample.

<figure><img src="image_22.png" /><figcaption>Figure A3. Examples of drills</figcaption></figure>
Tripod System to suspend jackhammer

In order to ease the work you may use the help of hoist/winches, a tripod or other to lift of the jackhammer and gouge

<figure><img src="image_23.png" /></figure>

<figure><img src="image_24.png" /></figure>

Fixing head for the 3 legs, so you can slip iron
square chunks (See slide below)

Rod with chain to hook the winch / hoist

<figure><img src="image_25.png" /></figure>

<figure><img src="image_26.png" /></figure>

Tripod set with legs to about 2/3 pieces
Length legs about 3,30m.
<figure><img src="image_27.png" /></figure>

**Example of commercial systems (light and heavy versions):**

<figure><img src="image_28.png" /></figure>

**Light tripod**

<table><tr><td>Article no.</td><td>02.01.01</td></tr><tr><td>Max. tensile force</td><td>6,5 kN</td></tr><tr><td>Total leg length</td><td>3 x 1,5 m</td></tr><tr><td>Working height</td><td>Ca. 3,9 m</td></tr><tr><td>Net weight</td><td>44 kg</td></tr><tr><td>Legs</td><td>Ø 50 mm</td></tr><tr><td>Snatch block</td><td>20 kN</td></tr></table>

**Heavy tripod**

<table><tr><td>Article no.</td><td>02.01.04</td></tr><tr><td>Max. tensile force</td><td>20 kN</td></tr><tr><td>Total leg length</td><td>3 x 1,65 m</td></tr><tr><td>Working height</td><td>Ca. 4 m</td></tr><tr><td>Net weight</td><td>108 kg</td></tr><tr><td>Legs</td><td>2 single Ø 70 mm<br>1 double Ø 80 mm</td></tr><tr><td>Snatch block</td><td>20 kN</td></tr></table>
Heavy tripod set-up procedure:

1. The heavy tripod is delivered in pieces. Attach the legs' top ends as shown in the figure at right.

2. Fold out the legs of the snatch block (6) and lay them wide apart on the ground.

3. Slide the extension pieces (9) over the legs' top ends. Lock them with bolts and nuts.

4. Attach the end-pieces with point (10) to the extension pieces (9). Mount the frame (11) on the Ø80-mm leg (8). Lock with bolts and nuts.

5. Attach the pulley with hook to the snatch block (6). Make sure the hook control is on.

<figure><img src="image_29.png" /></figure>

**<u>How to use a tripod</u>**

<figure><img src="image_30.png" /></figure>

**<u>Adapt a jack Hammer to a tripod</u>**

The jackhammer has been modified (Figure A4). An iron frame has been added so that jackhammer can be attached at the tripod in order to better distribute the weight and to assure the security once suspended.

- Jackhammer is suspended with a winch hook / hoist in order to move/lift up and down easily.

- to this iron frame we welded a metal ring on which is hooked the winch hook / hoist.

- Jackhammer length 1m
<figure><img src="image_31.png" /><figcaption>Figure A4. Modified jackhammer</figcaption></figure>

## Drilling

- Once the sampling point is prepared (e.g. depth, litter, stones, ....), pull up the jackhammer with help of the hoist.

- Then insert the gouge into the jackhammer and start to drill.

- Before and during drilling, when using percussion gouges with window and cutting segment, make sure the window is closed properly and the cutting part of your gouges is well attached

- Control the drilling angle.

<figure><img src="image_32.png" /></figure>

Once the necessary drilling depth is achieved, there are several ways to remove the gouge:

- A very basic and laborious way is the steel lifting jack and lever.

- A chain is tightly placed around the soil column (by scale) in order to pull up the column.

- Before removing the soil column with the tripod/chain - shake/row with the gouge by inserting a metal bar to the top of the gouge. While "rowing" the gouge comes off the soil more easily.
<figure><img src="image_33.png" /></figure>

- Another way is to use of a rod puller which is either one-man operated extractor, two-man operated extractor or hydraulic extractor

<figure><img src="image_34.png" /></figure>

By using a tripod or other setup using a hoist/winch, you may attach the gouge to the hoist and then by slightly "rowing" and up-moving the gouge with help to the chains you extract the gouge.

<figure><img src="image_35.png" /></figure>
<figure><img src="image_36.png" /></figure>

<figure><img src="image_37.png" /></figure>