PRS Technology

Ion exchange resins have been used in agricultural research since the mid 1900's. Reviews of ion exchange principles and applications have been published by Qian and Schoenau 1997 and Qian and Schoenau 2002.

Dr. Jeff Schoenau, internationally recognized for his contributions to the fields of soil fertility and plant nutrition, developed the PRS® Probes in 1992 at the Saskatchewan Centre for Soil Research (University of Saskatchewan). Dr. Schoenau had been made aware of much previous research work related to ion bioavailability in a graduate class taught by Dr. J.W.B. Stewart. The class focused on the concept that in the soil as it exists in the field, ions of agronomic and environmental interest such as nitrate, phosphate, potassium, cadmium, etc. are not available unless they can move to a root where they can be absorbed. Much of this knowledge was based on work by Dr. S.A. Barber of Purdue University published in a 1984 book entitled Soil Nutrient Bioavailability. It was knowledge of this concept, together with the realization that ion exchange resins in membrane form come closest to resembling a root surface, which led to Dr. Schoenau's concept of placing the membrane directly in soil to act as a root simulator. Dr. Schoenau and his graduate student, Mr. Weize Huang, pursued this concept and found that the amount of ion absorbed on a buried resin membrane in the lab and directly in the field predicted measurable differences in soil fertility and plant uptake that were observed on a variety of soils. A plastic applicator device was designed, with the assistance of the Saskatchewan Research Council, to assist in easily inserting the membrane into the soil. This basic design, with modifications, is the current embodiment of the Plant Root Simulator® probe. The University of Saskatchewan Technology Transfer Office filed patent applications for the technology in 1992. Successful patents also have been awarded in Canada, Australia, Europe, New Zealand, the United States, and by the World Intellectual Property Organization.

Dr. Schoenau's research associates, postdoctoral fellows, graduate, and undergraduate students also contributed to development and testing of the PRS® Probes through research in the following years. This collaborative work led to the development of resin membranes as a tool for assessing plant macro- and micro-nutrient availability in soil, salinity and sodicity, heavy metals, and herbicides. The PRS® Probes have now been used in research projects all over the world and research performed with the PRS® Probes has been published in numerous refereed journals. The ability to assess ion dynamics in situ under actual field conditions represents a significant breakthrough in the challenge of understanding soil nutrient and contaminant bioavailability.