Can I put on some heat shrink for the top 5 inches you recon? What do you think?
I use a pair of stainless steel cooking skewers driven into the soil about 10mm apart. My measuring technique leaves the two probes unpowered except when I'm actively taking a reading, and powers them briefly to take the reading, them powers them with the reverse polarity for the same duration - the goal of the reverse polarity wasn't to do with corrosion but to stop electrolysis from moving ions around in the soil which I thought might affect the accuracy long-term.
I'm not a chemist but I'm pretty sure that using stainless steel as an electrode will release chromium and in some forms this is toxic.
I'm not a chemist but I'm pretty sure that using stainless steel as an electrode will release chromium and in some forms this is toxic. Since the currents are going to be really small, perhaps it's not as big a problem as it would be if you were using it in electrolysis or plating but I'd advise against stainless steel electrodes until someone of appropriate education could give an all clear. My own interest is in a system to remind me to water my herbs so the possibility of chromium release is a nopety nope for me.
So we had better start throwing out all our stainless steel cooking pots then!