Author
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Corwin, Dennis |
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SCUDIERO, ELIA - University Of California |
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Submitted to: Methods of Soil Analysis
Publication Type: Book / Chapter Publication Acceptance Date: 7/19/2016 Publication Date: 8/30/2016 Citation: Corwin, D.L., Scudiero, E. 2016. Field-scale apparent soil electrical conductivity. In: Logsdon, S., editor. Methods of Soil Analysis. 1st Volume. Madison, WI: Soil Science Society of America. p. 1-29. doi: 10.2136/methods-soil.2015.0038. Interpretive Summary: Soil is extremely heterogeneous. The heterogeneity of soil is reflected in its spatial variability or change in physical and chemical properties over distance both horizontally and vertically. It is the extreme complexity of soil spatial variability that makes the study of soils so difficult. Soil spatial variability influences any soil-related process at field and landscape scales including the fate and movement of contaminants in soil, the quality or health of soil, and within-field variation in crop production, to mention a few. One of the most powerful and reliable tools for characterizing soil spatial variability is the mapping of apparent soil electrical conductivity (ECa). Maps of ECa can be used to direct soil sampling and the soil samples are analyzed for the chemical and physical properties of concern to establish maps of their spatial variability. From the maps of spatial variability field- to landscape-scale problems can be tackled. It is the goal of this book chapter to provide the step-by-step methodology for the characterization of soil spatial variability using ECa-directed soil sampling. Guidelines, special considerations, protocols, and strengths and limitations are presented for mapping soil properties using ECa. Land resource managers, farmers, extension specialists, and Natural Resource Conservation Service field staff are the beneficiaries of field-scale maps of soil properties. Technical Abstract: Soils are notoriously spatially heterogeneous and many soil properties (e.g., salinity, water content, trace element concentration, etc.) are temporally variable, making soil a complex media. Spatial variability of soil properties has a profound influence on agricultural and environmental processes such as plant-water-soil interactions, water flow, and solute transport, resulting in within-field plant yield variation and degradation of soil quality, just to mention a few. Field-scale mapping of spatial variability and monitoring of temporally dynamic soil properties is necessary for a variety of edaphic activities, such as soil surveys, reclamation and remediation, crop selection, site-specific management, and soil quality assessment. There are various approaches for characterizing soil spatial variability, but none of these has been as extensively investigated and is as reliable and cost effective as apparent soil electrical conductivity (ECa) directed soil sampling. Geospatial measurements of ECa are well-suited for characterizing the spatial distribution of soil properties because they are reliable, quick, and easy to take with GPS-based mobilized ECa measurement equipment. Directed soil sampling based on geo-referenced measurements of ECa is a proven and robust means of characterizing the spatial variability of any soil property that influences ECa including sol salinity, water content, texture, bulk density, organic matter, and cation exchange capacity. It is the goal of this methodology paper to provide an overview of the field-scale characterization of soil spatial variability using ECa-directed soil sampling. Guidelines, special considerations, protocols, and strengths and limitations are presented for characterizing spatial and temporal variation in soil properties using ECa-directed soil sampling. Land resource managers, producers, extension specialists, Natural Resource Conservation Service field staff, and university, federal, and state researchers are the beneficiaries of field-scale maps of soil properties. |
