Hi I am working on a hobby project hopefully building something like the "parrot flower power". I have found out how to measuring moisture content of the soil while still avoiding corrosion, using capacitance and high frequency.

However I cannot figure out how to measure fertilizer/salinity of the soil without corrosion.
The people behind parrot power says advertise they are measuring electrical conductivity to determine to determine this, which makes sense, but I cannot figure out how to do it without corrosion

Any ideas?

 

Perhaps an intermittent AC signal?

 

Perhaps an intermittent AC signal?

@Toebs
Keep the conductivity measurement voltage below the oxidation potential of the metals you risk corroding. Below 0.1 V should be safe.

 

Use carbon or platinum electrodes.

 

I was going to mod the Flora reference design by electric imp inspired by the VH400 moisture sensors made by Vegetronix. Theres no metals exposed, but maybe I need that or carbon electrodes.

Can this be worked with?
https://electricimp.com/docs/hardware/resources/reference-designs/flora/

 

Have you found the answer?