Effect of Daily Soil Temperature Fluctuations on Soil Electrical Conductivity as Measured with the Geonics~(R) EM-38

摘要

Soil electrical conductivity (EC_a) measured by electromagnetic induction (EM) using the EM-38 has shown promise as a soil survey tool. Soil temperature influences EC_a readings, and temperature can fluctuate considerably in the upper 10 cm of the soi l during a day, EC_a readings were taken in the horizontal and vertical dipole orientations once an hour from 8 a.m. to 8 p.m at four sites on three separate days to determine if EC_a values were influenced by diuinal temperature variations. Soil tempera ture readings were taken at the same times at four depths. EM-38 readings remained steady at all four sites all 3 days. Linear regression analysis when temperature in the upper 10 cm was plotted against EC_a yielded low r~2 values and slopes, indicating no correlation between soil temperature in the upper 10 cm and EC_a values. Diurnal changes in soil temperature do not significantly influence soil EC_a readings obtained with the EM-38 under the conditions encountered during the study.