want to measure surface soil moisture - need help

[jston...@cabq.gov]

Hi there. I am a meteorologist with the City of Albuquerque's Air
Quality Division. I issue dust alerts to area contractors when I expect
sustained winds >20 mph. It helps the contractors avoid the fines of
our fugitive dust program. Wind speed is only half the equation though.
It would be useful to have some measurement of moisture in topsoil,
i.e. within a half-inch or so of the surface. Most of the sensors at
sowacs appear to be used for measuring moisture below the surface. Does
anyone know of a reliable instrument and/or method for measuring
topsoil moisture?

-Jeff

[jston...@cabq.gov]

[Garry Boyd]

I supply simple dial hygrometers to a company who mount them in a block of
polystyrene for use by concrete contractors, tilers etc. on concrete
surfaces to measure surface humidity. The air entry is from the back, the
indicator facing up. This simple approach might work in your application.
There are also RF probes used in the marine industry that might do the job
with recalibration.

Regards
Garry Boyd
----------------------------------------------------------------------------
Met Instruments Weather Monitoring Equipment
Ph. ++64 6 364 7254 fax: ++64 6 364 7213
Http://www.MetInstruments.co.nz
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[Doug]

Jeff,

It's a bit unconventional but some people have thought of using the leaf
wetness sensor to determine when the surface soil is wet or dry. I don't
know what type of sensitivity you are looking for. The LW sensor returns a
value of 0 - 15 (with 0 being dry). This sensor could be connected to A
WatchDog model 525 weather station
(http://www.specmeters.com/WatchDog_Weather_Stations/WatchDog_Model_525_Weather_Station.html)
to collect wind speed/direction, air temperature and moisture. Other weather
station options are possible if you are interested in other parameters
(rainfall, relative humidity, etc.).

Doug Kieffer
Spectrum Technologies
23839 W. Andrew Rd.
Plainfield, IL 60544
ph 800-248-8873
815-436-4440
fx 815-436-4460
do...@agmeters.com
www.specmeters.com

----- Original Message -----
From: <jston...@cabq.gov>
To: <sow...@googlegroups.com>
Sent: Tuesday, February 15, 2005 6:45 PM
Subject: want to measure surface soil moisture - need help


>
>

[Brendon Duncan]

Hi Jeff,

You may be able to use Aquaflex sensors to do the job. They could measure
the moisture in the top 2-inches of soil. The Aquaflex sensor is a flat
tape about an inch wide and 10' (3m) long. It measures the moisture in the
soil up to about 1 inch away from the tape. It is usually buried vertically
(standing on its edge) at least 4 inches deep, but you could bury it down
flat horizontally, just 1 inch from the surface. The moisture reading from
the Aquaflex would then give you an average of the top 2 inches. It
measures about 6 Litres (370 cubic inches) of soil along its length, so it
will give you a good indication of what is going on.

Please let me know if you have any more questions. You can also go to
www.Aquaflex.co.nz for more information.


Best Regards,

Brendon Duncan
Streat Instruments

[jston...@cabq.gov]

Marty asked:

"How many sensors would you require and how do you plan on handling the
data?"

We need at least 2 sensors. One for the east side and one for the west
side of town. The instruments need to be able to work with an ESC
datalogger and report at least twice a day. Once an hour would be even
better. We have a polling computer that polls all the stations in our
monitoring network once per hour. Thus we need a device that can do the
job without any help from a human(e.g. not a hand-held device). I view
the data from my office.
Thanks for all of your responses. I have archived them and will use
them in examining our options.

-Jeff