PRS Technology

Typical field burials: PRS® Probes were designed to be inserted vertically into the uppermost soil layer because this is where most soil nutrients are released and roots are most active.  PRS® Probes are typically buried for one to four weeks.  Consecutive or distributed burial periods may be used to determine seasonal variations in nutrient supply rates.  Soil conditions (temperature, moisture, etc.) are monitored to assist with interpretation.

Field burials with root exclusion:  PRS® Probes can be inserted into root-exclusion cylinders or similar systems that minimize nutrient uptake by plants in order to obtain gross estimates of nutrient release.

Horizontal burials under plant residues: PRS® Probes can be placed horizontally on the soil surface below plant residues to measure nutrient release and leaching from plant residues decomposing in the field or LFH layers below the forest floor (Huang and Schoenau, 1997).

Subsoil monitoring: PRS® Probes can be used to monitor nutrient supply rates in subsoil layers by burying PRS® Probes horizontally in the side of an excavated soil pit (Huang and Schoenau, 1997) or at the bottom of a soil core or access tube.  Soil can be replaced after the PRS® Probes are inserted to maintain more natural soil environmental conditions.

Under water: PRS® Probes can be buried underwater to measure nutrient supplies in sediments or peat layers. The probes can be retrieved using a fishing line tied to each PRS® Probe handle.

Lab incubations: PRS® Probes can be used in short-term burials (e.g., 24 hours) with soil samples brought up to field capacity in order to obtain standardized measurements of soil nutrient supply.  Long-term incubations can be used for mineralization studies (Qian and Schoenau, 2005; MacKenzie and Quideau, 2012).  Growth chamber experiments may be used to compare cumulative nutrient supply rates measured using the PRS® Probes with plant nutrient uptake at the end of the growth period conditions (Qian and Schoenau, 2000). PRS® Probe sandwiches can be used to determine short-term nutrient supply (1 to 24 hour) from small soil samples.

However PRS® Probes are used, it is very important to ensure complete contact between the soil and the resin membrane of the PRS® Probe to achieve accurate results and consistency among PRS® Probe measurements. Nutrient supply rate is determined based on a specific surface area of soil. If there is incomplete contact between the membrane and the soil, then the soil surface area actually supplying ions to the membrane is different than that assumed in the calculation.