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I really like the addition of the web camera - it's a nice bonus on top of the more traditional temperature/humidity/light/moisture readings that most people incorporate into these DIY systems. Much better than what I made the first time I built one of these things.[0]

The one thing that made my scratch my head was your approach to measuring moisture. There are several very reliable methods for measuring soil moisture directly (changes in resistance, capacitance, time domain reflectometry, etc) that will give you exactly what you are looking for here.

"Therefore, we felt it was fair to assume that watering based on moisture level is impossible and that GreenPiThumb is doing the best it possibly can, given certain inexorable limits of the physical world."

This just isn't true. The sensor you picked up from Sparkfun should give you decent measurements for a while before degrading gradually depending on your soil chemistry.

[0] I ran a consumer soil moisture IOT company for a few years that was sold to Scotts Miracle Gro in 2016.




Oh you may be exactly the person I need to talk to! I'm looking for a soil humidity sensor that is able to permanently sit in my garden and accurately measure soil humidity and soil temperature. Do you have any advice?

Currently I'm using this one: https://www.adafruit.com/product/1298

But after 3-4 waterings, it reads 95-100% consistently, regardless of the temperature. I've tried 2 of their sensors and have had the same problem.


> time domain reflectometry

Can you point us in the right direction on this? The wiki doesn't make it clear how it would be used for measuring soil moisture.


Sure - this paper (PDF warning) is a decent place to start learning about how the process works. http://quebec.hwr.arizona.edu/classes/hwr432/2014/jones02-TD...

I haven't looked at the industry in a couple of years, but I think that many of the high-end commercial sensors use some variation of this technique.





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