Re: Hand feel vs instrumentation: Pros and Cons of Both

[owner-sowacs@aqua.ccwr.ac.za]

Washington State University published an official soil moisture "feeling"
method instructional guide several years ago.  Although perhaps not technically
"scientific," it could be considered so in the classical sense.  Scientists
based the method on an implied hypothesis, experimentation and conclusions,
etc.

Personally, I believe that social and cultural aspects of farming contribute to
a grower's success--staying in touch with the Earth and  "Muddy Boots"
management enhance the more "scientific" methods developed in academic circles.

Cosmology quickly demonstrates that many so called "facts" readily contridict
each other.  Perhaps grasping the soil communicates needs more subtle than the
immediate to become part of an overall system of subconscious decisions.  Go
ahead, prove me wrong.

owner-sowacs@aqua.ccwr.ac.za wrote:

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> Dear Soil Moisture Fellows:
>
> I've always wanted to pose a question regarding the effectiveness of
> instrumentation vs the traditional method of the hand feel method and using
> weather based evapotranspiration models. So without further ado.....
>
> Here in Central California, there are a number of individuals and companies
> making their living poking the soil with an auger, feeling the sample and
> estimating the amount of 'available moisture'. They then apply this
> knowledge to current ETo conditions/crop coefficients and calculate an
> irrigation schedule for their clients.
>
> Coming from a research background, I am not personally familiar with the
> soil-feel procedure. The method is not considered to be 'scientific' nor
> sufficiently quantitative. In research, we always used instrumentation
> (neutron probe, FDR, TDR, tensiometry, heat dissipation or lysimeters).
>
> I can understand that the soil-feel method has several advantages over
> instrumentation;
>
>  - One can cover much more territory and hence integrate the field's
> irrigation needs a tad better than point source instrumentation
>  - For annual or row crops, there are no wires or widgets sticking out of
> the field to encourage tractor blight
>  - It is 'potentially' a more cost effective method from the grower's
> perspective
>
> However, I see some down sides too:
>
>  - Feeling the soil is subjective
>  - It is labor intensive (some of the soil feel schedulers begin to wonder
> how long their bodies will hold up in later years)
>  - For deep rooted crops, it would be hard to assess how deep irrigations
> have penetrated the soil profile
>
> So what about instrumentation?
>
> Pros:
>
>  - One can use instruments as a dummy gauge, some what like a fuel gauge on
> a car, more or less 'feeling/sensing' the soil electronically through time
>  - Instrumented data can be integrated with computer software
>  - One can detect crop stress or on set of stress, especially if data is
> monitored continuously
>
> Cons:
>
>  - Placement of the sensor is KEY; does the instrument represent the root
> zone?
>  - With annual/row crops, the tractor blight problem mentioned above
>  - Maintenance or longevity issues
>  - Accuracy
>  - Soil type idiosyncrasies (2:1 cracking soils etc.)
>
> I would like to hear (objectively) from all the experts out in soil
> instrumentation 'cyberspace'. Many of you are either in the widget selling
> business or possibly in research. Hence, your perspective might be
> different than mine, maybe not.
>
> I truly believe instrumentation is the way to go, providing it can compete
> economically and agronomically with the soil-feel method.
>
> Comments folks............
>
> Cheers!
>
> Richard Mead
> United Agri Products
> mPower Specialist
>
> http://www.mpower3.com