Re: sensor to measure the conductivity of mud

[Steve Evett <srevett@ag.gov>]

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To all:

It is unfortunate that conductivity of mud or soil cannot be measured accurately with an inexpensive voltmeter. The reason is that the DC current used by the voltmeter causes ion diffusion and polarization between the electrodes. For this reason, conductivity meters for soils typically use an alternating current. The post by Martin Parkes gives some details good for saturation paste extracts.

Steve

At 08:49 AM 11/24/1999 +0000, you wrote:
>NOTE:  To get off this list, send email to majordomo@aqua.ccwr.ac.za
>with the body of the message containing the line:
>unsubscribe sowacs
>
>It seems that a larger issue should be addressed.  Why would the 
>conductivity of
>mud be interesting?  The conductivity will depend primarily on salinity or
>ionization--not water content.  Conductivity can easily be measured with a
>$20.00 voltmeter by inserting two wires along a common axis and measuring the
>distance and resistance between, i.e., ohm-cm.
>
>owner-sowacs@aqua.ccwr.ac.za wrote:
>
>>
>> I am looking for the conductivity of mud (high water content soil). Can you
>> recommend something?
>>
>> Do you know the Hanson company? Somebody told me that company has
>> conductivity meter. Can you give me the contact if you know that company.
>>
>> Thank you and regards,
>> Wendy Ko
>> Earth products China Ltd.
>>
>> [Can anyone help Wendy?
>> Measuring swc in mud would effectively be measuring 100% saturation. But how
>> does one define how muddy mud is? Above saturation (completely filled
>> pores), can a percentage water over 100% wrt bulk density be used? Or should
>> we be considering the soil as a percentage of the water?!?
>> Please post replies through sowacs, Bruce]
>
>
>
>

___________________
Steve Evett, Soil Scientist
USDA-ARS, 2300 Experiment Staton Rd., Bushland, TX 79012 USA 806-356-5775, FAX: 806-356-5750
srevett@ag.gov, http://www.cprl.ars.usda.gov/programs/