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Status of Soil Electrical Conductivity Studies by Central State Researchers

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  032339,  2003 ASAE Annual Meeting . (doi: 10.13031/2013.13838) @2003
Authors:   Cinthia K. Johnson, John W. Doran, Bahman Eghball, Roger A. Eigenberg, Brian J. Wienhold, Bryan L. Woodbury
Keywords:   Electrical conductivity, electromagnetic induction, geophysical sensors, site-specific management, precision agriculture, sustainable management, field-scale experiments

Practical tools are needed to identify and advance sustainable management practices to optimize economic return, conserve soil, and minimize negative environmental effects. Current research in the central US was reviewed to consider the utility of bulk soil electrical conductivity (ECa) as an assessment tool. Measured ECa can be used to track N dynamics in soil. It can detect variations in crop-available N due to manure, compost, commercial fertilizer, and winter cover crop treatments. Selection of appropriate ECa sensors (direct contact, electromagnetic induction, or time domain reflectometry) can improve sensitivity to N fluctuations at specific soil depths. Surveyed ECa has the potential to rapidly assess N mineralization early in the growing season, information essential for calculating fertilizer rates for site-specific management (SSM). Yet, in a sandy loam soil no correlation was found between ECa (0 to 75 cm) and soil inorganic N (0 to 30 cm), indicating that care must be taken when interpreting ECa. In a dryland cropping system, ECa-based management zones delineated soil characteristics and crop yields to provide a framework for SSM, and for appraising and statistically evaluating field-scale experiments. Clearly, use of ECa fosters a largescale systems approach to experimentation that addresses many sustainability issues. This approach may also encourage farmer involvement and acceptance of sustainable management practices. Yet, ECa interpretation is highly location and soil specific. Additional research is needed to investigate the interactive effects of soil, weather, and management on ECa and the geographic extent to which specific applications of this technology can be applied.

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