another question the circuit seems to latch in the high state and when i abruptsl contact the probes together it goes back to the low state. My high state shorted probes is 4.65v and my low state high-z on the probes is 2.12v does this seem reasonable. I also had another question in my case i am only looking for 3 threshhold DC voltages to trigger watering, so my microcontroller will be looking for only 3 set dc voltages. Would it be easier to use the soils resistance to adjust the gain on an op amp producing a range of values based on my op amps gain. Almost like a thermister would be used for temperature. Im not doing data logging so i only need minimal accuracy say dry, medium dry, and wet. But if the output from your design is supposed to be from 2.11 - 4.65V and i van get rid of that latching effect then i can make that work.