Calibration of Electromagnetic Induction for Regional Assessment of Soil Water Salinity in an Irrigated Valley

Electromagnetic instruments are increasingly being used for in situ analysis and mapping of soil salinity in irrigated soils. This study develops calibration models for salinity assessment over regional scales on the order of tens of thousands of hectares. These models relate apparent soil electrica...

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Bibliographic Details
Published in:	Journal of irrigation and drainage engineering Vol. 132; no. 5; pp. 436 - 444
Main Authors:	Wittler, James M, Cardon, Grant E, Gates, Timothy K, Cooper, Curtis A, Sutherland, P. Lorenz
Format:	Journal Article
Language:	English
Published:	Reston, VA American Society of Civil Engineers 01-10-2006
Subjects:	Agricultural and forest climatology and meteorology. Irrigation. Drainage Agronomy. Soil science and plant productions Biological and medical sciences calibration electrical conductivity electromagnetic induction techniques equations Fundamental and applied biological sciences. Psychology General agronomy. Plant production irrigated conditions Irrigation. Drainage mathematical models prediction soil salinity soil temperature soil water content TECHNICAL PAPERS Colorado USA, Arkansas R Irrigation Soils Electrical conductivity Soil moisture Valley Electromagnetic induction Water engineering Calibration Salinity
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Summary:	Electromagnetic instruments are increasingly being used for in situ analysis and mapping of soil salinity in irrigated soils. This study develops calibration models for salinity assessment over regional scales on the order of tens of thousands of hectares. These models relate apparent soil electrical conductivity measured with the EM-38 electromagnetic induction meter (Geonics Ltd.) to traditional laboratory-measured saturated paste electrical conductivities ( ECe ) . The study area is located in the Lower Arkansas River Valley, Colo. and is divided into two regions. At each of 414 randomly selected calibration sites, an EM-38 reading was taken and multiple soil samples were extracted for analysis. The sites chosen have soil ECe values ranging from 1 to 18 dS∕m , gravimetric water contents (WC) from 0.02 to 0.4, and textures ranging from sands to clays. The best model for predicting soil ECe in both study regions is bivariate nonlinear and includes EM-38 vertical readings ( EMV ) and WC as covariates. Uncertainty in the calibration equations is addressed and tests are conducted at 48 independent sites. Results indicate that, while uncertainty is considerable in regional scale surveys, electromagnetic instruments can be calibrated for rapid reconnaissance of soil water salinity, providing reasonably accurate identification of salinization categories.
Bibliography:	http://ascelibrary.aip.org/iro/ ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1
ISSN:	0733-9437 1943-4774
DOI:	10.1061/(ASCE)0733-9437(2006)132:5(436)