PRS Technology

No calibrated correlation can be made between PRS® Probe nutrient supply rate data and soil nutrient concentrations determined using conventional extractions, nor is it warranted. The nutrient supply rates measured with the PRS® Probes are unlike data generated from a conventional soil extraction for nutrient concentrations (i.e., ppm). Chemical extractions are static measures or indices of nutrient pools (i.e., total 'available', and organic) at a point in time, while the PRS Probes provide a dynamic measure in situ of ion flux over time to a sink with a constant (i.e., quantifiable) surface.

Note: the nutrient supply rates cannot be multiplied by two to provide an estimate of nutrient availability on a volume basis (i.e., kg/ha for 15 cm depth).

The PRS® Probe heralds a new area in functionally viewing the dynamic chemistry at an adsorbing surface. In simulating the mechanism of nutrient uptake used by plant roots, the PRS® Probe improves the accuracy of monitoring the soil nutrient supply. Although, short-term PRS® Probe supply rates can be well correlated to traditional chemical extractions (Table 1), one should not expect that the conventional chemical extraction indices to have anything more than a general relationship to the dynamic flux measured by the PRS® Probe during long-term burials. The reasons for this are simple. Only the PRS® Probe accounts for temporal variability in nutrient availability due to: soil moisture and temperature; mineralization and immobilization; ion activity; buffer power; and ion diffusion.