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In response to feel and appearance comments from Richard Mead.... I believe that you left out one "pro" to the feel and appearance method. It is a terrific technique in spotting moisture measurement device failure, or "missed" device calibration. It is an excellent (and safe) technique in estimation of variations between two accurate "fixed point" measurement in the same field. I have use it to "calibrate" neutron probe. A few months ago I offered a suggestion to a proposal aired in SOWACS concerning an updated cataloging of soil moisture sensing devices currently used. If I recall correctly, my recommendations was for a review of improvements in the tactile and visual evaluation of the soil moisture estimation method. At this point, I would suggest one enhancement: using step wise logic. I did not get a response to my suggestion. There are several professional and commercial "realities" for the apparent lack of interest in promoting the "feel and appearance" art form. Most of the (agronomy-irrigation) consultants in Oregon, Washington, Montana, and Idaho use (partially or totally) "feel and appearance". Most consultants with an agronomy background are looking for more than moisture when they visit a field. An experienced (agronomy) consultant is a real detective; his (shields up) sensory array process (nutrition, pathology, entomology) information in an integrated way. The USDA has a very good publication (in color) on "feel and appearance". One of the problems with a large portion of currently available devices is translation of the "reading" to a usable soil moisture volumetric converted value. Another separate problem is the estimation of volumetric "field capacity". Generations of soil science practioners have struggled with these problems. In 1999, the Idaho Department of Water Resources will be delivering Irrigation Scheduling to about 45 farmers, with three fields each. The ET estimates will be converted to "meaningful" information such as "hours or specific system operation", and other convenient information such as "minimum and maximum ground speed" recommendations. There will be a follow-up field check of moisture with high quality neutron probe data every two weeks (by IDWR after setup and calibration) and secondary "feel and appearance" checks (by IDWR and the farmer) between the neutron probe visits. My personal opinion is that feel and appearance is the stand alone method, and instrumentation should be the "add-on" activity. IDWR is doing winter workshops for cooperating farmers, part of which is a "feel and appearance" class. This program is designed to integrate both the ET approach and the Soil Moisture Approach to the regional sprinkler irrigators. If we are successful, the method will be easily transferrable to a large or unlimited number of irrigators in 2000. The method of converted ET data delivery will be web page, automated voice, BBS, and fax. I actually prefer US mail for grahical neutron probe data delivery (less than 24 hours), Feel and appearance "data" has been tagged as "subjective". I propose that instrumentation data is unfairly credited with greater credibility simply because it includes single digit specivity. I suggest that comperable results will come from both types of data when used in a "step wise" or "fuzzy logic" type of analysis (i.e. Pivot Data Output Might Be: STOP AND WAIT, GO SLOW, GO MEDIUM, GO FAST) Robin Wells, P.E. 1341 Fillmore Street Suite 200 Twin Falls, Idaho 83301 rwells@idwr.state.id.us -----Original Message----- Date: Monday, December 21, 1998 4:00 PM From: owner-sowacs@aqua.ccwr.ac.za <owner-sowacs@aqua.ccwr.ac.za> Subject: Hand feel vs instrumentation: Pros and Cons of Both >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