SOWACS: recording soil moisture in high clay soils?

[Gregg Dill]

gregg.dill@gov.ab.ca writes to the sowacs list:
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Dear Arie,

Now that we have your attention, do you - or anyone else - have an 
automated solution for recording soil moisture in high clay soils (25 - 
40% clay) for research plots?

Sincerely,
Gregg Dill

_______________________________________________
> Gregg Dill, P.Eng.  Irrigation Engineer
> Alberta Agriculture, Food and Rural Development
> 100, 5401 - 1st Avenue South
> Lethbridge, Alberta  T1J 4V6
> Telephone +1 (403) 381-5116    FAX +1 (403) 381-5765
> Web site:  http://www.agric.gov.ab.ca
_______________________________________________




Bruce  -owner of sowacs <bruce@sowacs.com>
12/18/2003 01:21 AM
Please respond to Bruce  -owner of sowacs

 
        To:     Bruce Metelerkamp <bruce@sowacs.com>

        Subject:        SOWACS: home made gypsum blocks - is it possible?




Arie Nadler writes to the sowacs list:
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Dear Robbin Josef,

Not many topics can trigger my response so fast.

Using gypsum blocks is like praying for water when lost in a dry, hot day 
in
a desert:

The act of praying relieves you temporarily of the pains but does not help
in practical solution.

Gypsum blocks are not linear in their response to different levels of 
water
content, therefore you have to calibrate them.

It is difficult to find two similar ones so you have to calibrate all of
them, and remember who is who.

But due to gypsum dissolution, salt precipitation, OM plugging and a few
more factors, the calibration (you worked so hard to get) changes 
gradually
at an unknown rate.

Lack of inexpensive, direct, simple and reliable methods for measuring WC
still does not justifies the gypsum blocks adventure.

My tip: use tensiometers.


Arie Nadler
Dept. of Soil Physics
Institute of Soil, Water, and the Environment
A.R.O., Volcani Center, Min. of Agriculture
POB 6 Bet Dagan, Israel, 50250
Tel: 972-3-9683865
Fax: 972-3-9604017
Home: 972-8-9404161
Email: vwnad@volcani.agri.gov.il

----- Original Message ----- 
From: "Bruce -owner of sowacs" <bruce@sowacs.com>
Sent: Wednesday, December 17, 2003 11:04 AM
Subject: SOWACS: home made gypsum blocks - is it possible?

>
> Robbin J. Kavunkal writes to the sowacs list:
> ===8<==============
> Dear Friends,
> I'm doing a project on auto irrigation. Can anyone
> please tell me if gypsum blocks, for measurement of
> soil moisture ,can be made by me at home? If so how
> can i make them?
>  An answer to my query will surely help me a lot to
> continue with my project.
> Thank you.
> Robbin Joseph
>

===8<==============
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