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I was using a Campbell Scientific CR1000

Hi Ennai, since I shot the video I substantially improved the logger. You'll only need a UNO and a Adafruit Datalogger Shield. All the info on how to build it is in this article: www.sciencedirect.com/science/article/pii/S2468067219300070 I hope this helps.

Diovani, sure, email me at gerardo.spinelli@gmail.com and I'll email you the sketch

Hi Charmon, thank you for your comment. In this video I show a logger that I built from components but now you can get a data logging shield already built here: www.adafruit.com/product/1141 You just need to plug it into an Arduino Uno. There is a lot on forums on how to read a 4-20ma signal with an Arduino. This is one of the threads: forum.arduino.cc/index.php?topic=105703.0 I hope this helps! Good luck, Gerry

No problem! Thank you for watching!

Hi Fouzia, thanks for your comment. I have no protocol, basically you collect water coming out of the branch in a given time. You'll get, say cm^3/min. Then you visually estimate the area of xylem that conducts water (this is the tricky part). You can measure with a caliper the inner and outer diameter of the ring of xylem where you see water coming out. Then you calculate the area of the ring with simple geometry. Once you get the area in cm^2, you divide the volume/time by the area and you'll get a velocity in cm/min. Try two or three velocities, by varying the pressure in the water flowing through the branch. Then you compare this velocities with what measured by the sap flow sensor and this way you can figure out a calibration factor. Work fast, because I noticed that the conductivity in the excised branch decreases in terms of hours. I hope this helps!

Hi Gerardo, thanks alot for your reply, concerning estimate the area of xylem that conducts water, you can use Safranin O solution (0.1%) as a colorant. The colored area will be measured and considered the xylem area in cm2. When I asked about the protocol, I wanted to talk about the components of the device used to force a flux of solution through a trunk section (ie: PVC tube, manometer ....)