The facts about Van Walt’s Rhizon Samplers

April 8, 2015

Rhizon samplers are used for repeated and reliable sampling of all dissolved components in a soil solution. They are very suitable for pot, cylinder and column research (Macro Rhizons for field research). Rhizon samplers are used when several soil solution samples are needed of the same soil volume in research for:

• Plant uptake of soluble nutrients as nitrate
• Solubility of metals in soil
• Transport of soluble components in soil
• Accumulation of salts, etc
• Environmental research.

The porous plastic material (PES) of the Rhizon wets spontaneously and has standard 0.15 micron pores. The samplers are supplied with coextruded tubing (PE inside / PVC outside) 1 mm internal diameter, luer connector and protective cap. The sampler is re-enforced by a wire. Dissolved organic and inorganic matter will not be absorbed by the soil moisture sampler. The sampler is placed preferably horizontally in moist soil. Water acts as a lubricant during inserting. Due to the minimal disturbance the soil will quickly resettle, resulting in a good sampler-soil contact.

Standard Rhizon soil moisture samplers are inserted through the wall of undisturbed soil columns and pots with plants. A sample is obtained by placing the sampler under vacuum. The vacuum is obtained using a vacuum tube or a syringe. Van Walt’s Rhizon soil moisture samplers are supplied in various designs: Macro Rhizons and Micro Rhizons.

For inserting in pots during filling, the Rhizon soil moisture sampler type FLEX with nylon strengthening wire is available. For sampling metals a special Rhizon soil moisture sampler is available, with a length of 10 cm and a diameter of 2.5 mm, with glassfiber re-enforced strengthening wire and 10 cm coextruded tubing. This soil moisture sampler type and Rhizons with stainless steel strengthening wire are designed for sampling in undisturbed soil cylinders (core samples) or in pots with growing plants.

Van Walt supplies the Rhizon soil moisture sampler in a standard set with: Rhizon soil moisture samplers with a length of 10 cm (complete with PVC/PE tubing, connectors and protective caps), a needle set with protective caps and a set of glass vacuum tubes with a 9 ml contents. The standard set can be extended with various accessories such as: short Rhizon soil moisture samplers (5 cm porous material), syringes (to be used instead of vacuum tubes) connectors for connecting the syringes (including spacers for blocking the syringes), (black) PE extension tube, silicone connecting tubing to connect the extension tubing to the soil moisture samplers.
Our Macro Rhizon soil moisture sampler is especially suited for use in the field. The sampler has a length of 9 cm and a diameter of 4.5 mm. For installation at greater depths a standard sampler with PVC extension pipe can be used.

The benefits of using Rhizon soil moisture samplers:

• Minimal disturbance of hydraulic properties of the soil
• Low dead volume < 0.5 ml
• Minimal ion exchange capacity (less than soil)
• pH is not changed by sampling
• Complete sampling systems (can be cleaned before use to suit specific demands)
• Sample is filtered and can be analysed directly
• Inexpensive.

Visit our Soil Solution pages for more information.