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Highlighting agricultural developments, problems, research, & issues for central coast CA
Comments:
by Mark Vawter
on September 29, 2019 at 11:48 AM
Very well written instructions for the tensiometer. I was wondering if you had any directions on how to make a connection to a data logger With a 4-20 mA current input? Are there some off the shelf parts that you recommend?
by Michael D Cahn
on September 30, 2019 at 10:37 AM
"Very well written instructions for the tensiometer. I was wondering if you had any directions on how to make a connection to a data logger With a 4-20 mA current input? Are there some off the shelf parts that you recommend? " Mark Vawter  
 
Thanks for your comment Mark,  
 
I use a voltage output pressure transducer (RSU-V)sold by irrometer Inc. to interface the tensiometer with a datalogger. I have been having very good luck with these transducers interms of stability over time and accuracy.  
 
Michael Cahn
by John Clemens
on September 30, 2019 at 5:03 PM
What is unique about the expensive epoxy/hardener you recommend? Since I'm not going to build several hundred tensiometers, I'd like to find a less costly alternate epoxy/hardener combination. Is bonding to the pvc pipe the problem?
Reply by Michael D Cahn
on February 4, 2021 at 11:11 AM
Hi John,  
 
The epoxy/hardener was recommended by soil moisture corp. because it bonds PVC to ceramic materials. We did not try other epoxy products. You might experiment with a similar type of epoxy.
by Michael D Cahn
on September 30, 2019 at 5:20 PM
John,  
I understand your concern with buying the expensive epoxy and hardener. It works well and can be use for gluing many tensiometers but has a limited working life time (1 year).  
 
You can try other epoxy products that are suitable for plastic and ceramic. I suggest to experiment with whatever brand that you choose on one tensiometer first. I have used these expoxies in the past but soil moisture corp. cautioned us against the off-the-shelf epoxy products. One problem that we had was that the epoxy did not harden sufficiently and bond well to the pvc.
by renzo manchinelli
on March 6, 2020 at 5:56 PM
Hi i'm from argentina, is there a way to contact You? Some mail or number? Thank you
by Michael D Cahn
on February 4, 2021 at 11:11 AM
Renzo,  
 
If you have specific questions you can contact me at mdcahn@ucanr.edu
by Stephen Hughes
on April 5, 2021 at 5:51 AM
Very helpful, thanks!
by Andre Kleynhans
on April 8, 2021 at 5:56 AM
Hi, I'm from South Africa  
 
What values on the meter would you say is dry and wet?
by Michael D Cahn
on April 12, 2021 at 7:32 PM
Hi Andre,  
 
For vegetables and berries, readings less than 20 to 25 kPa are considered moist. Dry conditions would be greater than 60 kPa (cbars). Tensiometers typically have readings less than 5 or 10 kPa after irrigating, corresponding to very moist conditions.
by Zunaid Vania
on November 5, 2022 at 10:46 PM
Since using a voltage output pressure transducer is an entirely different ballgame, I'm curious to know if Michael, Mark, or anyone else who has done this has information on connecting to a data logger?
Reply by Michael D Cahn
on November 11, 2022 at 9:33 AM
Hi Zunaid,  
 
Yes we routinely connect the tensiometer voltage output transducer to Campbell scientific dataloggers (models CR300, CR206, CR1000). Using a cell phone modem connection to the dataloggers, we automatically import and display tensiometer data in the free CropManage software developed and maintained by UC Cooperative Extension (cropmanage.ucanr.edu). Other types of dataloggers could also be used with the tensiometers but I use the Campbell loggers.
by Gerhard Oberforcher
on April 29, 2023 at 1:38 PM
Hi Everyone,  
 
Years ago I came across an article by Mr. Thalheimer that described a home built tensiometer utilizing a pressure sensor, read by an Arduino Board. The program was designed to log data in its memory for later evaluation. Should you be interested to learn mire about Martins work, follow the link below to researchgate that publishes the free article. The Arduino SW is also available from him by asking. I hope this bit if info might be helpful to you.  
 
I built a simple tensiometer with vacuum gauge and it works well.  
 
https://www.researchgate.net/publication/274776721_A_low-cost_electronic_tensiometer_system_for_continuous_monitoring_of_soil_water_potential/fulltext/563eb81108ae8d65c0144831/A-low-cost-electronic-tensiometer-system-for-continuous-monitoring-of-soil-water-potential.pdf?origin=publication_detail  
 
Regards,  
Gerhard
by Ultrasonic flow meter NZ
on November 28, 2023 at 5:26 AM
Your tips for selecting and installing ultrasonic flow meters are incredibly informative. The breakdown of key considerations and potential challenges is helpful for those navigating the selection process. Any specific brands or models you recommend based on your experience?
Reply by Michael D Cahn
on November 28, 2023 at 2:20 PM
Hi,  
 
Thank you for your comments. We did publish a short article that evaluate the accuracy of several flowmeters for metering fertilizer in a previous blog. We more recently have evaluated the accuracy of several models of larger flowmeters including an ultrasonic model from netafim. That article should be published in a few weeks.  
 
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=58011
Reply by Michael D Cahn
on November 28, 2023 at 2:21 PM
Hi,  
 
Thank you for your comments. We did publish a short article that evaluated the accuracy of several flowmeters for metering fertilizer in a previous blog. We more recently have evaluated the accuracy of several models of larger flowmeters including an ultrasonic model from netafim. That article should be published in a few weeks.  
 
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=58011
 
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