PRS Technology


Maximum adsorption capacity*

(meq/m2 membrane)


Maximum adsorption capacity of PRS® Probes.

Anion 149
Cation 237
*Based on empirical measurements of Cl- and Na+ adsorption.


Ion Maximum adsorption capacity Molarity Valence
To convert to milligrams per m2 (micrograms per 10 cm2) for a specific ion, multiply the maximum adsorption capacity by molarity and divide by valence (meq per mmol).
  mg/m2 meq/m2 mg/mmol meq/mmol
NO3--N 2086 149 14 1
SO42--S 2384 149 32 2
K+ 9243 237 39 1
Ca2+ 4740 237 40 2

Maximum adsorption capacity (mg/m2) = maximum adsorption capacity (meq/m2) * molarity / valence

Important notes

  • The rate of ion adsorption slows if >50% of maximum, e.g., if NO3-N > 1000 mg/m2.
  • These maximums are for a single nutrient only.  In soil, the maximum adsorption of a specific ion will usually depend on its activity relative to other ions (see here).