Thanks to both
yes, we are working with watermarks sensors and we take control readings several times per week with a hand device.
I would like to save readings each hour and to graph an water potential curve and maybe to see if the tree is suffering at some point.
About the temperature I've read that affects water potential readings by 1-3% per Celsius degree. So If I want readings for 1 month I can assume 10%water potential error but If I want readings for entire campaing (1 year) I'll need a temp sensor.
My doubts come from my lack of electronic knowledgement. I suppose man has to weld, to wire and to code different pieces and make it work properly.
At this moment I have it clear I need 4 analog pins to read the "electrical resistance" of the sensor. 1 analog pint more due to temperature sensor. Something to save or send the data (sure its not easy such as plug n play),a power supply and a code.
What dou you think is the easiest way to join these pieces for a noob??
Thanks again!