8 Electrical Conductivity and Soluble Salts
Last edited: 06NOV2023 NP
We are testing 3 methods in one: an initial reading after 30 mins, one before the end of the day (~ 6 hrs), and one that stands overnight. Modified from NRCS KSSL Laboratory Methods Manual; see references.
8.1 Materials
- EC reader
- D.D.I water (double deionized water, filtered campus DI water)
- Squeeze bottle of DDI
- Falcon Tubes, 50mL
8.2 Procedure
- Test calibration; see EC protocol.
- Put soil in Falcon Tube to the 10 mL line.
- Add 10 mL of D.D.I water to sample using a squeeze bottle.
- Vortex for roughly 30s and let sit for 30 mins. Record time, take a reading.
- Reading technique should be similar as pH, probe in at the same depth every time. Be mindful of the notation on the reader when recording
- Add 10 mL of DDI water, let sit for approximately 6 hrs, swirl/agitate/hand shake, record time, take a reading.
- Let sit for 24 hours (from the initial start time), swirl/agitate/handshake, and take a reading.
8.3 Calculations
No calculations are required for this procedure.
Use the following relationship to estimate the total soluble cation or anion concentration (meq L−1) in the soil. EC (mmhos cm−1)x10=Cation or Anion (meq L−1)
Use the following relationship to estimate the total soluble cation or anion concentration (meq g−1 oven-dry soil) in the soil. EC (mmhos cm−1)x20=Cation (meq g−1 soil) EC (mmhos cm−1)x20=Anion (meq g−1 soil)
Report prediction conductance to the nearest 0.01 mmhos cm−1 (dS m−1).
8.4 References and Notes
U.S. Salinity Laboratory Staff. 1954. L.A. Richards (ed.) Diagnosis and improvement of saline and alkali soils. 160 p. USDA Handb. 60. U.S. Govt. Print. Office, Washington, DC.
Kellogg Soil Survey Laboratory Methods Manual. (2022). Current Methods - Electrical Conductivity and Soluble Salts. p.550