Soil Water Samplers. Inert samplers can extract small or larger volumes of (pore) water from soils and sediments in a simple, non-destructive and repeatable manner. Different soil water samplers, developed by i) Rhizosphere Research Products, and ii) Sentek can be used to sample water from both unsaturated and saturated soils, and the extract can be used to measure dissolved compounds such as salt / nutrients, dissolved organic carbon, plant exudates incl. enzymes, or contaminants.
Sentek SoluSampler. Two types of robust, inert SoluSamplers with ceramic cups are available for large volume soil water sampling in the field (Table 6). Sampled solutes are frequently analyzed for nitrate and salinity (EC). Read more on SoluSamplers.
RRP Rhizon Samplers. Three major types of RRP Rhizons for soil pore water extraction are available :
Rhizon Sampler Accessories (syringes, vacuum vials) are listed in Table 5. Read below on characteristics of the Rhizon microfiltration membrane, and details on the sampling procedure. For continuous measurements of soil moisture content in larger diameter boxes, mesocosms, rhizotrons, and in the field see soil moisture sensors.
RRP MicroRhizons are mainly used in RhizonBoxes and Agar tests. They consist of two parts: a porous part (i.e. microfiltration membrane) of 8 mm with an outer diameter of 1 mm, and a PEEK tube (0.6*0.4 mm; 12 cm long) with a silicone connector that fits onto a syringe. The average pore size of the membrane is 0.15 µm, so no filtering of samples is required prior to analysis. The yield of MicroRhizons is up to 2 ml (depending on pore water availability). Because the MicroRhizon tubing is made of PEEK and a special adhesive, it can be steam sterilized.
For MicroRhizons, any standard syringe with a "tip" and a wooden retainer can be used for sampling. The MicroRhizons and the syringe tip are connected by a "silicone connector" - i.e. a small piece of silicone tubing.
Table 1 MicroRhizons & accessories for soil pore water sampling in RhizonBox back panels (RRP19.21.81), or with silicone sleeve (RRP19.21.83) for entry from the side of Rhizonboxes (4.5 mm holes).
Product #(Image) | Length, membrane [mm] | Length, tubing [cm] | Description |
19.21.81 | 8 | 12 | MicroRhizon, 8 mm porous, glued on 12 cm PEEK tube, silicone connector for syringe with tip, 10x - STANDARD - use with Rhizonbox 1.5 mm rear panel holes! Buy MicroRhizons online. |
19.21.82 | 8 | 12 | MicroRhizon, 8 mm porous, glued on 12 cm PEEK tube, PEEK guide (1.6 mm OD), silicone connector for syringe with tip, 10x |
19.21.83 | 8 | 12 | MicroRhizon, 8 mm porous, glued on 12 cm PEEK tube, with silicone sleeve, silicone connector for syringe with tip, 10x - use with Rhizonbox 4.5 mm side holes! |
19.21.84 | - | - | Accessory - PEEK tubing, 1.6 mm OD, guide tubing to push the MicroRhizon (19.21.81) into agar or other media, 5 cm |
19.21.85 | - | - | Accessory - PEEK extension tubing 0.6 x 0.4 mm, (including silicone connectors), 30 cm |
19.21.88 | - | - | Accessory - Syringe PP set [Syringe PP, 5 ml, tip, with wooden retainers 5 cm], 10x |
RB-Rhizonbox | - | - | Accessory - RhizonBoxes; Custom size or Online Shop |
Rhizon Samplers are used for (un-)disturbed soils (see types below), and are ideal to be positioned in Rhizoboxes and RhizonBoxes, pot experiments and the field. Rhizonboxes can be equipped with special 4.5 mm openings on the side wall(s) (e.g. at different depth) to insert CSS Rhizon samplers (diameter of 2.5 mm plus silicon sleeve to prevent leakage of water from the RhizonBox). They can be used to collect water from larger zones (length of porous parts: 5 cm or 10 cm) for analyzing macro and micro elements, dissolved organic carbon (DOC), exudates and enzymes, and dissolved gases. Using Rhizons with a 10 cm porous part, maximum yield of water is approximately 4 ml per minute. Rhizon Flex Samplers are particular suitable for sampling when installed in Rhizoboxes and Rhizonboxes during soil filling / set-up.
Rhizon SMS. For installation in disturbed soils, lab, greenhouse, and in upper layer in the field. For analysing macro elements, not suitable for analyzing metals and DOC. SS 316 strengthener wire (metal) can be bent permanently. Can be used in Rhizonboxes with restrictions (i.e. wait until soil contact is re-established). See Table 3 for details.
Rhizon MOM. For installation in disturbed soils, lab and greenhouse. For analysing macro and micro elements, dissolved gases and DOC. MOM samplers have a tip with a bulb (2.8 mm) and need several hours or days to achieve a good contact between soil and sampler. Strengthener is a a glass fibre wire. Can be used in Rhizonboxes with restrictions (i.e. wait until soil contact is re-established). See Table 3 for details.
Rhizon CSS. For direct sampling in cores, undisturbed soils and Rhizonboxes (with silicon sleeves, from side). For analysing macro and micro elements incl. metals, dissolved gases and DOC. CSS samplers have a flat tip (2.5 mm) of the diameter of the porous part. The direct contact between the soil and the porous part makes CSS samplers suitable for immediate sampling - when inserted e.g. through the side holes of Rhizonboxes. Strengthener is a 10-15 cm glass fibre wire. The porous membrane (5 or 10 cm in length) should be fully inserted into the soil and must be at least 0.5 cm away from the outside. 1st choice for Rhizonbox sampling from the side. See Table 2 for details.
Rhizon Flex. For disturbed soils or positioned during the filling of Rhizo(n)boxes (from the side holes OR top) or pots. For analysing macro and micro elements incl. metals, dissolved gases and DOC. Strengthener is a a nylon wire. The long tube length makes it easy to install them at the intended depth and from the top of Rhizoboxes. 1st choice for Rhizobox sampling when installed during set-up. See Table 2 for details.
MacroRhizon. For field research. For analysing macro and micro elements incl. metals, dissolved gases and DOC. They have a porous membrane (9 cm) with an outer diameter of 4 mm and a pore size of 0.15 µm. MacroRhizons are only available with female luer lock, suitable for creating a vacuum with syringes. Four lengths available are 0 (=direct sampling), 30, 60, and 90 cm tube length. Can also be used in large (i.e. > 3 cm deep) Rhizoboxes. See Table 5 for details.
Rhizon type are available in varieties (see Tables 2, 3 and 4 for details / product numbers):
Ask for silicone sleeve versions (i.e RRP product number # + S) to prevent Rhizonbox leakage from the sampler inlet holes (i.e. sleeves sealing the 4.5mm holes in the side of the Rhizonboxes). Alternatively, the gaps around the sampler tube can also be be sealed with Terostat or similar sealant.
Table 2. Rhizon types CSS and Flex for soil pore water sampling in RhizonBoxes and Rhizobox, and pot studies. Rhizon CSS (Rhizonbox, from side, immediately) / RhizonFlex (Rhizobox, from top during set-up) samplers are particular suitable for use with Rhizo(n)boxes. See Table 5 for Rhizon Sampler Accessories.
Product number (Image link) | Length, membrane [cm] | Length, tubing [cm] | Description of CSS / Flex Rhizon Product (Type / Variation) |
19.21.23S |
5 | 12 |
Rhizon CSS (for macro & micro elements incl. metals, dissolved gases and DOC in disturbed soils), can be inserted for direct sampling into Rhizonboxes through side holes, 0.15 µm pore size, 5 cm porous part, glued on 10 cm glass fiber wire as strengthener, tip flat, male luer, 10 per set; S = including silicone sleeve |
19.21.23FS |
5 | 12 | Rhizon CSS as above but with female luer, 10 per set, S = incl. silicone sleeve |
19.21.24, 19.21.24S | 10 | 12 | Rhizon CSS (for macro & micro elements incl. metals, dissolved gases and DOC in disturbed soils), can be inserted into Rhizonboxes through side holes, 0.15 µm por size, 10 cm porous part, glued on 15 cm glass fiber wire as strengthener, tip flat, male luer, 10 per set, S = incl. silicone sleeve |
19.21.24F, 19.21.24FS | 10 | 12 | Rhizon CSS as above but with female luer, 10 per set, S = incl. silicone sleeve |
19.60.23F, 19.60.23FS | 5 | 12 | Rhizon CSS (for macro & micro elements incl. metals, dissolved gases and DOC in disturbed soils), can be inserted into Rhizonboxes through side holes, 0.60 µm pore size, 5 cm porous part, glued on 10 cm glass fiber wire as strengthener, tip flat, female luer, 10 per set, S = incl. silicone sleeve |
19.60.24F, 19.60.24FS | 10 | 12 | Rhizon CSS as 19.60.23F (above) but with 10 cm porous part, glued on 15 cm glass fiber wire as strengthener, female luer, 10x, S = incl. silicone sleeve |
19.21.25 | 10 | 60 | Rhizon Flex (for macro & micro elements incl. metals, dissolved gases and DOC in disturbed soils), have to be positioned during the filling of Rhizoboxes, pots etc., 0.15 µm pore size, 10 cm porous part, glued on 60 cm PVC/PE tube, nylon wire as strengthener, male luer, 10 per set |
19.21.25F | 10 | 60 | Rhizon Flex as above but with a female luer, 10x |
19.21.26 | 5 | 30 | Rhizon Flex (for macro & micro elements incl. metals, dissolved gases and DOC in disturbed soils), have to be positioned during soil filling, 0.15 µm pore size, 5 cm porous part, glued on 30 cm PVC/PE tube, nylon wire as strengthener, male luer, 10 per set |
19.21.26F | 5 | 30 | Rhizon Flex as above with female luer, 10 per set |
19.60.26F | 5 | 30 | Rhizon Flex (for macro & micro elements incl. metals, dissolved gases and DOC in disturbed soils), have to be positioned during soil filling, 0.6 µm pore size, 5 cm porous part, glued on 30 cm PVC/PE tube, nylon wire as strengthener, female luer, 10 per set |
19.60.25F | 10 | 60 | Rhizon Flex as 19.60.26F but with 10 cm porous part, glued on 60 cm PVC/PE tube, nylon wire as strengthener, female luer, 10x |
Table 3. Rhizon types SMS and MOM for soil pore water sampling in pots, columns etc. (disturbed soil). See Table 5 for Rhizon sampler accessories.
Product number (image link) | Length, membrane [cm] | Length, tubing [cm] | Description of SMS / MOM Rhizon Product (Type / Variation) |
19.21.01 | 10 | 12 | Rhizon, SMS (for macro elements, not suitable for metals & DOC), 0.15 µm pore size, 10 cm porous part, glued on 12 cm PVC/PE tube, samplers have a SS 316 strengthener wire (can be bent permanently), male luer, 10 per set |
19.21.01F | 10 | 12 | Rhizon, SMS as above (19.21.01) but with female luer, 10x |
19.21.05 | 5 | 12 | Rhizon, SMS (for macro elements, not suitable for metals & DOC), 0.15 µm pore size, 5 cm porous part, glued on 12 cm PVC/PE tube, samplers have a SS 316 strengthener wire (can be bent permanently), male luer, 10 per set |
19.21.05F | 5 | 12 | Rhizon, SMS as 19.21.05 but with female luer, 10x |
19.60.01F | 10 | 12 | Rhizon, SMS (for macro elements, not suitable for metals), 0.6 µm pore size, 10 cm porous part, glued on 12 cm PVC/PE tube, samplers have a SS 316 strengthener wire which can be bent permanently, female luer, 10 per set |
19.60.05F | 5 | 12 | Rhizon, SMS as 19.60.01F but with a 5 cm porous part, glued on 12 cm PVC/PE tube, samplers have a SS 316 strengthener wire (can be bent permanently), female luer, 10 per set |
19.21.21 | 10 | 12 | Rhizon, MOM (for macro & micro elements incl. metals, dissolved gases and DOC), 0.15 µm pore size, 10 cm porous part, glued on 12 cm PVC/PE tube, glass fiber wire as strengthener, tip with bulb (bulb diameter 2.8 mm), male luer, 10 per set |
19.21.21F | 10 | 12 | Rhizon, MOM as above with female luer, 10x |
19.21.22 | 5 | 12 | Rhizon, MOM (for macro & micro elements incl. metals, dissolved gases and DOC), 0.15 µm pore size, 5 cm porous part, glued on 12 cm PVC/PE tube, glass fiber wire as strengthener, tip with bulb (bulb diameter 2.8 mm), male luer, 10 per set |
19.21.22F | 5 | 12 | Rhizon, MOM as above with a female luer, 10x |
19.60.21F | 10 | 12 | Rhizon, MOM (for macro & micro elements incl. metals, dissolved gases and DOC), 0.6 µm pore size, 10 cm porous part, glued on 12 cm PVC/PE tube, glass fiber wire as strengthener, tip with bulb (bulb diameter 2.8 mm), female luer, 10 per set |
19.60.22F | 5 | 12 | Rhizon, MOM as 19.60.21F (above) but with a 5 cm porous part glued on 12 cm PVC/PE tube, glass fiber wire as strengthener, female luer, 10x |
Table 4. MacroRhizon types for field soil pore water sampling. Outer diameter of membrane 4.5 mm. See below for notes on the installation of MacroRhizons.
Product number (image link) | Length, membrane [cm] | Length, PVC tubing [cm] | Description of MacroRhizon type |
19.21.35 | 9 | 0 | MacroRhizon for installation in the topsoil or horizontal in profile pit walls, 0.15 µm pore size, 9 cm porous part with glass fiber strengthener, no tube = direct connection to female luer, 10 per set |
19.21.38 | 9 | 30 | MacroRhizon for angled installation in subsoil, 0.15 µm pore size, 9 cm porous part with glass fiber strengthener on 30 cm PVC tube. female luer, 10 per set |
19.21.39 | 9 | 60 | MacroRhizon as 19.21.38 but with 60 cm PVC tube, 10 per set |
19.21.36 | 9 | 90 | MacroRhizon as 19.21.38 but with 90 cm PVC tube, 10 per set |
19.21.37 | 9 | - | MacroRhizon - Spare Membrane (Replacement part) |
19.21.51 | - | - | MacroRhizon Insertion Tool, stainless steel pin (4 mm OD, 10 cm long) on 100 cm PVC tube |
Soil Auger / corer | Consider a Sentek Soil Auger, or a small diameter VSI Soil Corer (e.g. 48 mm ID) for installation of MacroRhizons at greater soil depth |
What accessories do you need for sampling? This depends on the type of Rhizon ... read more on Ways how to do sampling with Rhizons below.
Table 5. Rhizon Accessories for soil pore water sampling with the different Rhizon samplers. Essentials for Rhizonbox studies marked in green. (Sampling method: male luer connectors M = needle & vial, OR female luer connectors F = syringe + retainer sampling!).
Product number (Image link) | Description of Accessory | |
19.21.02 | Needle 40 mm, diameter 0.8 mm, with protecting cap, 10x | |
19.21.03 | Vacuum vials 9 ml, plastic, one-time use, 50x | |
19.21.04 | Syringe set 10 ml female-female, [10 ml syringe + female-female Luer lock connector + wooden retainer 7 cm], 10x | |
19.21.08F | Female-Female luer lock connector (turns a male luer into a female luer), 10x | |
19.21.08M | Male-Male luer lock connector (turns a female luer into a male luer), 10x | |
19.21.09.7 | Wooden retainer 7.0 cm, for syringe 10 ml, 10x | |
19.21.09.8 | Wooden retainer 8.5 cm, for syringe 20 ml, 10x | |
19.21.09.10 | Wooden retainer 10 cm, for syringe 30 ml, 10x | |
19.21.09.12 | Wooden retainer 12 cm, for syringe 50 ml, 10x | |
19.21.10 | Connector/Retainer set, [Luer lock connector 2*female + wooden retainer 7 cm], 10x | |
19.21.13 | Silicone tubing, 1 m, 6 * 2 mm (+ guide wire), slips over and seals tubing outside diameter 2.5-3.2 mm, for about 30 connections | |
19.21.14 | PE Extension tubing, semi rigid, black, 3.2 *1.0 mm, 50 m | |
19.21.16 | PVC/PE extension tubing, flexible, transparent, 2.5 * 1.0 mm, 50 m | |
19.21.18 | Luer lock stopcock 2-way, for sampler flushing without vacuum loss, male-female luer, 10x | |
19.21.19 | Luer lock stopcock 3-way, for sampler flushing and removal of O2, male-female-female luer, 10x | |
19.21.44 | Extension tubing PVC/PE with Luer lock connectors (M, F), 10 x 1 m | |
19.21.45 | Extension tubing PVC/PE with Luer lock connectors (M, F), 10 x 0.5 m | |
19.21.88 | Syringe set 5 ml, [Syringe 5 ml, tip, with wooden retainer], 10x - for MicroRhizons | |
19.21.48 | Syringe set 10 ml, [Syringe 10 ml, male luer lock, with wooden retainers 7 cm], 10x | |
19.21.46 | Syringe set 20 ml, [Syringe 20 ml, male luer lock, with wooden retainers 8.5 cm], 10x | |
19.21.49 | Syringe set 30 ml, [Syringe 30 ml, male luer lock, with wooden retainers 10 cm], 10x | |
19.21.47 | Syringe set 50 ml, [Syringe 50 ml, male luer lock, with wooden retainers 12 cm], 10x | |
RB-Rhizonbox | RhizonBoxes, dedicated rhizonboxes allowing to enter MicroRhizon and CSS Rhizon samplers from a perforated back panel (grid of 1.5 mm holes) / top or side (4.5 mm holes), respectively. Custom-sized Rhizonbox or standard sizes in the online shop | |
RB-Rhizobox | Rhizoboxes, best used with RhizonFlex. See Rhizoboxes - Custom configuration or standard sizes in the online shop | |
EV-101 | EV-101 Evacuator for vacuum vials, to extract soil water with rhizons (male connectors) into (reusable) evacuated glass vials instead of using syringes or one-time exetainers - allowing fast, easy and parallel sampling. |
The microfiltration membrane of (Micro-)Rhizon samplers is made of a hydrophilic, inert polymer with no ion exchange properties. Once wet, the membrane is only permeable for liquids, not air. Rhizons have very small diameters and low dead volumes and are easy to handle; once installed for one experiment, they can be used many times.
Store in a dry, normally ventilated place, away from sources of heat, ignition and direct sunlight. Store between 0 and 50°C (32 - 122F). The membranes should not be exposed to freezing.
For sampling rhizosphere pore water, you need a (Micro-)Rhizon sampler and accessories to create a (partial) vacuum (see images below).
What is the difference? The advantage of vacuum vials is that the sample does not come into contact with air. The advantage of needles/syringes is that the vacuum can be easily restored by pulling back the plunger. However, male-to-male and female-to-female luer connectors are available to easily "correct" your initial choice of sampler luers later. If you use syringes to create a vacuum, wooden retainers can be used to block the plunger -which keeps the vacuum. If you use vacuum vials, you can buy them pre-evacuated or prepare them cost-effectively using the Vacuum Vial Evacuator EV-101. Simply connect a needle to the male Luer lock on Rhizon samplers (or use a female-to-female connector) and insert it through the septa of the vacuum tube.
If you cannot extract soil water, you may have forgotten to remove the (blue or red) protective cap from the Rhizon before use. Please check and try again. If the protective cap is already off you may have to wait a little longer. The porous membranes of any (Micro-)Rhizon samplers must be completely wet before you can apply vacuum.
If you are interested in testing the response of specific roots or rhizosphere compartments to changes in the soil environment (e.g. salts, heavy metals or other pollutants, dissolved carbon, etc.), you may consider using (micro)rhizons to inject a solution into the soil (next to a specific root or soil region) instead - or use RhizonIrrigators for setting specific irrigation treatments by passive suction or active outflow.
MacroRhizons are only available with a female Luer lock, suitable for creating a vacuum with syringes. It is recommended that the MacroRhizons be installed horizontally in a soil profile wall (direct), or drilled / cored soil hole at an angle of 30 to 45°. This will prevent rainwater from running along the PVC pipe and directly into the membrane. An installation tool (19.21.51) is available for placing the MacroRhizons in any hole larger than ~2 cm in diameter and up to ~85 cm deep. Select MacroRhizons of appropriate lenght (direct, 30, 60, 90 cm). Install in prolile wall (direct) or core the soil to the depth where the top end of the 9 cm sampling membrane will be placed, then use the installation tool to create a small (4 mm) hole for insertion of the MacroRhizon membrane section, allowing the sampler to fit tightly in largely undisturbed soil. Backfill the hole above, preferably to approximate the soil profile pattern. Make sure the Luer lock remains clean. For best results, it is recommended to wait 2-3 weeks before sampling; if there is no rain, consider watering the area at the beginning to allow the soil to settle tightly around the sampler. A vacuum for sampling can only be applied when the membrane is wet! You may consider installing MacroRhizons in parallel with Minirhizotron tubes - this will allow you to characterize soil water patterns at different depths along the rooting profile. Drill & Drop soil moisture probes, or access tube-based soil moisture EnviroScan sensors can provide complementatry information on spatial and temporal soil water dynamics.
Sentek SoluSampler. The SoluSAMPLER is a large soil solution sampler, a lysimeter cup that draws water from the surrounding soil and stores it in an inert ceramic cup for collection and analysis. The large sample cups are ideal for accurate, site-specific analysis of soil water salinity and nitrate content. Suitable for installation at various depths and field conditions. Rugged and durable design. See manual below for details.
Table 6. SoluSamplers for Soil Water Sampling and Accessories. SoluSamplers are most suitable for field applications and large sample volumes.
Product number | Product name | Description |
ST05500 | Solu Low Flow Soil Water Sampler | Suitable for most applications, in particular fine textured soil (clay etc ). |
ST05505 | Solu High Flow Soil Water Sampler | Suitable for light textured soils and moist soils (for rapid sampling). |
Solu Accessories | Stopcock, syringe (with standard tip) available. Soil corer and other tools for SoluSampler installation can be custom made on demand. |
Samples of soil pore water are extracted from the ceramic cup using a large syringe. See the description and the SoluSampler Manual below (pdf) for details on installation and operation.
Installation:
Generally, it takes about two weeks after installation for the SoluSampler to provide a representative soil water sample. During this two week period, discard two or more extracted samples to avoid unrepresentative samples.
Sampling:
Analysis of the collected soil water can be carried out by: