Measure moisture content of dirt?

[Chris Cooper]

Is there a reasonable way to measure the moisture content of the earth - say
in the garden, or the yard? And then you could decide how much to water,
based on how dry the ground is?

Thanks!
Chris

 

[Dana Raymond]

Google "Soil Moisture".

Try this one: http://www.specmeters.com/Soil_Moisture/index.html

Dana Frank Raymond

"Chris Cooper" <chrisnews@sc3.net> wrote in message
news:3f628912$0$62076$75868355@news.frii.net...

Is there a reasonable way to measure the moisture content of the earth -
say
in the garden, or the yard? And then you could decide how much to water,
based on how dry the ground is?

Thanks!
Chris

 

[Garrett Mace]

"Chris Cooper" <chrisnews@sc3.net> wrote in message
news:3f628912$0$62076$75868355@news.frii.net...

Is there a reasonable way to measure the moisture content of the earth -
say
in the garden, or the yard? And then you could decide how much to water,
based on how dry the ground is?

Thanks!
Chris

Google search for soil moisture meter turned up
http://www.veseys.com/store.cfm?product=2134

 

[Chris Cooper]

Hum ... very interesting ... I realize I should have specified, I want to
run the output of the moisture meter into a computer and do the analysis
there. Also, cost is a critical component.

I will provide the computer - so on the specmeters.com site, the WaterMark
sensor looks possible, if they tell you what the output from the sensor is
so I can properly hook it to an ADC ...

Thanks!
Chris

"Dana Raymond" <draymond@austin.rr.com> wrote in message
news:sAw8b.5571$z32.72@twister.austin.rr.com...

Google "Soil Moisture".

Try this one: http://www.specmeters.com/Soil_Moisture/index.html

Dana Frank Raymond

"Chris Cooper" <chrisnews@sc3.net> wrote in message
news:3f628912$0$62076$75868355@news.frii.net...
Is there a reasonable way to measure the moisture content of the earth -
say
in the garden, or the yard? And then you could decide how much to
water,
based on how dry the ground is?

Thanks!
Chris

 

[Stepan Novotill]

On Fri, 12 Sep 2003 21:03:48 -0600, "Chris Cooper" <chrisnews@sc3.net>
wrote:

Is there a reasonable way to measure the moisture content of the earth - say
in the garden, or the yard? And then you could decide how much to water,
based on how dry the ground is?

Well, the computer joystick interface contains four A-D converter

channels, but you need to isolate from ground (literally!), so I guess
that is easiest to do by sticking two wires in the ground and coupling
them into a VCO through a HI-Z audio transformer for ground isolation.
Divide the VCO frequency using a 4040 and feed the output into your
computer's breakfast port, on one of the handshaking lines. Your
software can time the period of the waveform and read the moisture
content from a lookup chair.

If this sounds too complicated then I'm not shure what to recommend.

 

[The Captain]

"Chris Cooper" <chrisnews@sc3.net> wrote in message news:<3f628912$0$62076$75868355@news.frii.net>...

Is there a reasonable way to measure the moisture content of the earth - say
in the garden, or the yard? And then you could decide how much to water,
based on how dry the ground is?

Thanks!
Chris

Soil conductivity increases with dampness, so you can use a wheatstone
bridge with the soil forming one of the arms of the bridge. Adjusting
a potentiomenter on the opposite arm for a null over the bridge will
give you a measurement of soil moisture.

If you want to leave the moisture measurer in the soil as a permanent
probe, it would be advisable touse AC across the bridge, rather than
DC, which will turn your metallic probes into metal oxide probes
rather rapidly.

If you need a circuit diagram, drop me a mail and I'll send you one.

John

 

[Rich Grise]

"Chris Cooper" <chrisnews@sc3.net> wrote in message news:<3f628912$0$62076$75868355@news.frii.net>...

Is there a reasonable way to measure the moisture content of the earth - say
in the garden, or the yard? And then you could decide how much to water,
based on how dry the ground is?

Thanks!
Chris

My Mom (RIP) had a little moisture meter, which was basically a probe
with a little battery at the end (two dissimilar metals - the dirt
is the electrolyte) and a galvanometer. You could tear one of those
apart and look at the output voltage range, which you'd than have
to amplify and all that.

Good Luck!
Rich