Submitted to: Computers and Electronics in Agriculture
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/15/2004
Publication Date: 3/1/2005
Citation: Corwin, D.L., Lesch, S.M. 2005. Characterizing soil spatial variability with apparent soil electrical conductivity: I. Survey Protocols. Computers and Electronics in Agriculture. 46:103-133. Interpretive Summary: Over short distances soils are highly variable with respect to chemical and physical properties. This is called spatial variability. Surveying a field for apparent soil electrical conductivity (ECa) is one means of characterizing the spatial variability of soil for a variety of important properties such as bulk density, texture, water content, salinity, and organic matter. Spatial measurements of ECa are a quick, easy, and reliable means of mapping and monitoring changes in these properties in space and time. In the past, researchers have used surveys of ECa with inconsistent results partly because of the lack of a standardized set of ECa survey protocols. A set of detailed protocols was developed to guide researchers in conducting an ECa survey and to assist researchers in understanding and interpreting ECa survey measurements. This will provide researchers with a set of steps to follow in their data collection that will assure reliability, consistency, and compatibility of ECa survey measurements and their interpretation for characterizing spatial variability. The information to characterize spatial variability plays a significant role in (i) the movement of chemicals through soil, (ii) soil quality, and (iii) precision agriculture.
Technical Abstract: Spatial characterization of the variability of soil physico-chemical properties is a fundamental element of (i) soil quality assessment, (ii) modeling non-point source pollutants in soil, and (iii) precision agriculture. Apparent soil electrical conductivity (ECa) is a quick, reliable measurement that is frequently used for the spatio-temporal characterization of edaphic (e.g., salinity, water content, texture, and bulk density) and anthropogenic (e.g., leaching fraction) properties. It is the objective of this paper to provide the protocols for conducting a field-scale ECa survey (Part I) and to apply these protocols to a soil quality assessment in central California's San Joaquin Valley (Part II). The protocols are comprised of eight general steps: (i) site description and ECa survey design, (ii) ECa data collection with mobile GPS-based equipment, (iii) soil sampling design, (iv) soil core sampling, (v) laboratory analysis, (vi) calibration of ECa to ECe, (vii) spatial statistical analysis, and (viii) GIS database development and graphic display. The developed protocols provide the guidelines to assure reliability, consistency, and compatibility of ECa survey measurements and their interpretation.