The adoption of the ion-exchange resin technology for routine monitoring of soil nutrient dynamics has been limited. Primarily, this is due to the practical limitations of using ion-exchange resin formulations employing a mesh casing or other porous fabric that often rupture and/or are difficult to wash free of fine roots or soil particles. The use of the PRS™-probes, comprised of cation- or anion-exchange resin membranes encased in a plastic holding device, greatly facilitates the use of ion-exchange resin technology in the field.

Advantages of the PRS™-probes include: easy insertion with minimal soil disturbance; flat structure ensuring a constant (i.e., quantifiable) adsorptive surface area, therefore, supporting the modeling of increased nutrient supply over the growing season given an area of ion sink (i.e., growing root system); direct contact exchange with no secondary ion diffusion through mesh or porous material required; mechanistically similar to a plant root in its natural environment; easy removal and cleaning; and, reusable. Furthermore, the replacement of PRS™-probes in the same soil slot provides a true in situ measure of temporal nutrient availability.

When analysing the PRS™-probes, a single 0.5 N HCl elution step removes at least 95 % of adsorbed nutrients, compared to the mesh casing formulations that require at least two elutions, using a stronger acid, to remove the majority of adsorbed nutrients. This added difficulty of sufficiently desorbing nutrients during the elution step requires extra time and money, and may lead to increased variability of data if inadequately done.