🚀 go-pugleaf

In article <6079@mtecv2.mty.itesm.mx>, ggonzale@mtecv2.mty.itesm.mx (Gabriel Gonzalez) writes:
> Hello there!
> 
> I'm working in an automatic watering system for this campus, and I need
> to know how can I measure the humidity level of the soil. I need to get
> an electrical signal representing this parameter. I've searched in
> catalogs (like Omegas's) and found nothing. I've thought about measuring
> the earths resistance, but found no easy way of doing it. It doesn't
> have to be a very accurate measurement, but I need a good (read it
> stable) signal to work with. If you can give me any ideas I'll
> appreciate it.
> We are building up a control system using a DP-31 with a PS; we monitor
> the water flow an level of several deposits and wells.
> Thanks for your help.
> 
> Gabriel Gonzalez (CALVIN)
> ggonzale@mtecv2.mty.itesm.mx

the method I've seen is a tube stuck into the ground with a porous ceramic
plug in the bottom. The tube is filled with water and evacuated. A pressure
gauge indicates the partial pressure and hence moisture content. We played
round with attaching an electronic pressure sensor for remote monitoring,
projected ended up on the low-priority shelf.

these tubes are commercially available, check out irrigation specialists

> 
-- 
Bruce Spedding
Materials Science and Performance
Industrial Research Ltd,     Fax: +64-4-569-0132
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