LaMotte CDS 5000 Conductivity Meter - Manual (Page 13)

TESTING SOIL
The Total Dissolved Solids (TDS) level of soil samples can be determined
using the CDS 5000. A soil extraction is made using distilled water, and
the TDS level measured.
1. Fill a 50 mL beaker with sample soil. Tap lightly to eliminate trapped
air. Remove excess soil from the surface.
2. Empty beaker into a 250 mL widemouth flask. Add 100 mL of
distilled water. Stopper and shake vigorously. Wait 30 minutes.
NOTE: During the waiting period, vigorously shake the sample three
or four times.
3. Filter contents of flask, collecting filtrate in a beaker or other suitable
container.
NOTE: LaMotte Company offers a funnel (order code 0459) and
filter paper (order code 0465) which can be used for this filtration.
4. Set TDS knob to desired multiplication factor.
NOTE: 0.7 is a commonly used multiplication factor.
5. Press “°C” button to turn the meter on.
6. Set SLOPE knob to the 12 o’clock position.
NOTE: If meter was calibrated according to procedure on page 7,
leave SLOPE knob set in the same position.
7. Insert temperature and conductivity probes at least 1/2" into sample.
8. Gently stir with conductivity probe until reading stabilizes. Press
“
mS/ppm” button. Record reading as msiemens/cm.
9. If a 1 appears on the far left side of the display, the reading is out of
range. Repeat procedure using “mS/ppt” button. Record as
msiemens/cm. To convert to
msiemens/cm, multiply reading by 1000.
Record as
msiemens/cm.
10. Press “OFF” button when finished testing. Rinse probe with distilled
water and dry thoroughly before storing.
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