LaMotte SMART3 Soil Operator's Manual page 80

 SOLUBLE SALTS (TOTAL DISSOLVED SALTS)
Most plants will get along well at soluble salts concentrations of below 1000 parts per
million. However, greenhouse and many sensitive garden plants may be damaged if
the soluble salts are over 500 parts per million of chlorides, particularly some of the
most sensitive legumes. If the soluble salts are greater that 1000 parts per million,
the chlorides and sulfates should be determined to learn whether the soluble salts are
chlorides or sulfates. In calcareous soils, the sulfates represent gypsum and have little
eff ect on the production of plants.
PROCEDURE
1. Fill a 50 mL beaker (0944) with the soil to be tested, tapping it lightly to eliminate
2. Empty the contents of the beaker into the 300 mL bottle (0991). Add 100 mL of
3. Cap the bottle and shake vigorously. Allow to stand for thirty minutes. During the
4. Filter the contents of the bottle using funnel (0459) and fi lter paper (0463) and
5. Determine the TDS reading of the sample by following the instructions for the TDS
6. To convert conductivity to Soluble Salts (Total Dissolved Solids), use the following
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any trapped air and then strike off the surface.
deionized water.
thirty minute waiting period the bottle should be shaken vigorously three or four
times.
collect the fi ltrate in a 100 mL bottle (0990) which is then used as a conductivity
chamber.
Meter.
formula.
ppm Soluble Solids (Total Dissolved Solids) = Micromhos/cm @ 25°C x 0.7
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10 20
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SMART3 Soil Colorimeter 9.18
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