The element Potash has an isotope which is naturally radioactive: 40 K.
This isotope represents only 0,012 % of the total amount of Potash; therefore, Potash is not harmful for human life. However, this radiation can be used to determine Potash concentrations.
The amount of radiation from this isotope is quite small; therefore large material samples and large, sensitive sensors are required to use this radiation for quantitative measurements of Potash concentrations.
If this is not the case, then potash can be monitored using XRF. TEXAS will detect Potash concentrations in solids, while solved Potash in brines can be monitored using FLORIDA.