Regional Calibration of the EM-38 for Salinity Assessment in the Arkansas Valley. (6349)
Authors:
J.M. Wittler* - Colorado St. Univ.
G.E. Cardon - Colorado St. Univ.
C.A. Cooper - Colorado St. Univ.
Abstract:
The objective of this study was to develop a regional calibration between electrical conductivity (EC) values measured with the EM-38 probe (Geonics, Inc.) and saturated paste electrical conductivities (ECe). The study region is located in the lower Arkansas River Basin, CO and is divided into two study areas centered about Rocky Ford, CO (upstream of John Martin Reservoir) and Granada, CO
(downstream of the reservoir). As soil ECe measurements are highly correlated to soil paste electrical conductivities (ECp) (Rhoades et al., 1989), soil EC measurements were taken using a soil cup (SIW Kit, Hach Company, Inc.). At each randomly selected field site, an EM-38 reading was taken, and soil samples were collected at the surface, 12”, 24”, 36”, and 48” depths from the center, left, and right of the EM reading position. The field sites chosen have soil ECe’s ranging from 1-18 dS/m and are also varied in texture and soil moisture content. Regression analysis of soil ECe against EM-38 values yielded an r2 of 0.50 and 0.60 for the downstream and the upstream respectively. Multivariate analysis has helped to improve the r2 for the downstream and upstream areas to 0.55 and 0.69.
Speaker Information: James Wittler, Colorado St. Univ., 2005 Skyrock Rd., Loveland, CO 80538; Phone:
970-278-0258; E-mail: [email protected]
Session Information: Tuesday, November 2, 2004, 7:55 AM-9:00 AM Presentation Start: 8:00 AM
Keywords: EM-38; soil salinity; Arkansas Valley; electromagnetic probe
