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ECH2O Probe User's Manual 4. Collecting Data RAW: 0 (m3 /m) = 0.000571 x - 0.376 EG5: The EG5 is much less sensitive to variation in texture and electrical conductivity because it runs at a much higher measurement frequency. Therefore, its general calibration equation should apply for all mineral soils up to 8 dS/m. Its calibration equations are shown below for mineral soil, potting soil, and rockwool growing media: q=11.9*10-4*mV-0.401 (2) where mV is the output of the probe when excited at 2500 mV. Please note that the equation will reach a maximum at --60% volumetric water content (VWWQ in pure water. To display data on a scale from 0 to 100%, VWC should be modeled with a quadratic equation (which would result in a 100% VWC in water), but a linear equation fits the mineral soil VWC range as well as the quadratic, and linear equations are easier to deal with, especially since mineral soil typically saturates at —40 - 50% VWC. 17 mineral Soils According to our tests, a single calibration equation will generally suffice for all mineral soil types with electrical conductivities from 0.1 dS/m to 10 dS/m. Volumetric water content (q) is given by q = 8.5 * 10-4 * Raw_ 0.48 (1) where Rawis the output from the Decagon datalogger. If you are using a non -Decagon datalogger, VWC is given by q=11.9*10-4*mV-0.401 (2) where mV is the output of the probe when excited at 2500 mV. Please note that the equation will reach a maximum at --60% volumetric water content (VWWQ in pure water. To display data on a scale from 0 to 100%, VWC should be modeled with a quadratic equation (which would result in a 100% VWC in water), but a linear equation fits the mineral soil VWC range as well as the quadratic, and linear equations are easier to deal with, especially since mineral soil typically saturates at —40 - 50% VWC. 17