Bests & Worsts Reviews from Amazon

Surprisingly, no reviewer has recognized that this device acts as a battery. The anode and cathode are formed by the copper shaft and the lead tip. The electrolyte is the moisture in the soil. Low meter readings will result from low soil moisture (as intended) and, although not intended, from corrosion of the copper shaft or lead tip. So, clean the tip and shaft regularly with something like steel wool before inserting the probe in the soil. I bought 6 of these testers and all gave different readings until I used steel wool on the shaft and tip. After cleaning they all gave higher readings and did a great job of signalling the moisture content of the soil. You can test the device by submerging the tip and shaft in a few inches of water. If the meter's needle moves into the "wet" zone, no cleaning is needed. If the needle doesn't move quickly into the "wet" zone, cleaning as described.