Portable Probes to Measure Electrical Conductivity and Soil Quality in the Field

Soil electrical conductivity (EC) is a useful indicator in managing agricultural systems, but tools for convenient and inexpensive measurements in the field are generally lacking. Handheld conductivity probes were designed to evaluate in-field naturally occurring and human-induced total soluble electrolyte levels in soil and water. The probes were used to survey and monitor EC in the field and to assess soil and water quality as related to environmental stability and sustainable food production. A pencil-sized 16-cm probe (PP) was connected to a handheld Hanna (DiST WP 4) conductivity meter, resulting in an economical, compact, and easy to use device. The tool provided accurate and precise results compared with laboratory instrumentation under standardized conditions of soil water content and temperature. Soil samples, varying widely in texture and organic matter content, and having ECs ranging from 0.13 to 2.32 dS m were used for comparison. Mean values and coefficients of variation were similar for the PP and the commercial laboratory EC meter with values determined with the two instruments being strongly correlated (r 1⁄4 0.96– 0.99). The handheld and PP probes effectively replaced expensive and cumbersome laboratory and field instruments used to measure EC in water and soil samples. The Received July 1, 2005, Accepted July 11, 2005 This article is a joint contribution of the U.S. Department of Agriculture and University of Nebraska, Lincoln. Published as Journal Series Number 14402. Address correspondence to S. L. Arnold, USDA-ARS-SWCRU, 120 Keim Hall, University of Nebraska, Lincoln, NE 68583-0934, USA. E-mail: [email protected] Communications in Soil Science and Plant Analysis, 36: 2271–2287, 2005 Copyright # Taylor & Francis, Inc. ISSN 0010-3624 print/1532-2416 online DOI: 10.1080/00103620500196689