Instructions for Vitel Soil Moisture Probe:
Measurement and Data Processing
 Click here to download Vitel software
Sampling
You must first decided on the number and
location of samples within your study area. Since we are interested in both the spatial
average and spatial patterns of soil moisture content, it is necessary to assign
coordinates to each sampling location. In this way, we can map the surface and subsurface
distribution of soil moisture content across the study area. Local or relative coordinates
will suffice, and the coordinate system should be the same as that used to collect thaw
depths. If possible, the soil moisture measurements should be made at the same time as the
end-of-season thaw depths.
Field Measurement
Once you have decided on your sampling
locations, it is a relatively simple procedure to make measurements. To sample the soil
from 0-10 cm (since the probe tines are 10 cm long), orient the probe vertically and
carefully insert the tines into the soil. Then, switch on the power source and wait
several seconds. Set the channel selector switch to 1, then read and record the first
voltage. Change the selector switch to channel 2. Repeat the procedure until all four
voltages have been recorded. Turn off the power to conserve battery life. Further details
are available in the handout.
In many cases, it is also desirable to
obtain measurements of soil moisture at greater depth from the same location. To do this,
a tulip bulb planter has been provided. At a nearby (~0.5 m) location, use the tulip bulb
planter to extract a plug of soil 15 cm long. It may be necessary to first use the larger
unit to cut the organic mat, then the shorter bulb planter to grip and remove the plug.
Try to minimize disruption of the hole and plug. Insert the Vitel probe into the borehole,
switch on the power, and record the four voltage readings. Re-insert the soil plug.
You may wish to mark the sites so that
you can return to the same locations each year. Furthermore, it is useful to record the
type of soil that you encountered near the surface (0-10 cm) and at depth (15-25 cm).
Finally, if you are collecting both surface and subsurface readings from the same site, it
is probably best if you separate the readings since you will have two resulting data sets.
Data Entry in Spreadsheet
The next step is to record the data in a
spreadsheet. The file format is:
STATION # [space] SOIL [space] V1 [space] V2 [space] V3
[space] V4
The STATION # (number) is simply the
sample number. SOIL refers to the soil type, and V1-4 are the measured voltages at that
site. Further details are available in the Hydra Soil Moisture Probe User's Manual. Be
sure to enter the station# and soil type as an integer and voltages as a real number
(1.000 instead of 1). In general, use a soil type of sand (=1) if you are dealing with
organics. An example is given below, and there are sample input and output data files
included on the disk. Note that there are no column headings or commas to separate the
fields.
If you have collected two data sets, they
should be separated. However, the first column will be identical and the second column may
be the same.
166 1 2.107 1.993 1.942 2.15
167 1 2.069 1.992 1.943 2.151
168 1 2.052 1.989 1.942 2.151
169 1 2.037 1.987 1.944 2.15
170 1 2.022 1.984 1.946 2.15
171 1 2.009 1.983 1.948 2.149
Once the data has been entered, save the
file(s) as an ASCII text file, with an appropriate name, to the same directory where
HYD_FILE.EXE is located. The file should have a (.DAT) extension. Do not retain any column
headings, and use a space as a delimiter (no commas).
Processing
the Data
The data file you created in the
spreadsheet will be used as input into the DOS program HYD_FILE.EXE, which is provided on
the disk. Follow the instructions in the User's Manual. When running this program, keep in
mind that you must use a different output filename than the input filename, and be sure to
use the extension (.DAT) for both input and output files.
EXAMPLE:
Prompt: Enter Filename to be converted: SITE1.DAT
Prompt: Enter Output Filename:
OSITE1.DAT
The resulting output data file should be
sent to the CALM WWW site via electronic transfer or disk. In addition, be sure to include
the coordinates of the sampling sites.
FOR FURTHER INFORMATION, PLEASE CONTACT
Professor Kenneth M. Hinkel, Department of Geography, 400F Braunstein, ML
131, University of Cincinnati, Cincinnati, Ohio 45221-0131
Phone: (513) 556-3430, Fax: (513) 556-3370, E-mail: Kenneth.Hinkel@uc.edu |
