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Title: Tools for proximal soil sensing

item ADAMCHUK, VIACHESLAV - McGill University - Canada
item Allred, Barry
item DOOLITTLE, JIM - Natural Resources Conservation Service (NRCS, USDA)
item GROTE, KATHERINE - University Of Wisconsin
item ROSSEL, RAPHAEL - Commonwealth Scientific And Industrial Research Organisation (CSIRO)

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 2/3/2015
Publication Date: 4/1/2015
Citation: Adamchuk, V.I., Allred, B.J., Doolittle, J., Grote, K., Rossel, R.V. 2015. Tools for proximal soil sensing [Supplement to Chapter 4]. In: Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. Available at:

Interpretive Summary: Soil properties vary in space and time. As a consequence, at field and landscape scales, they are seldom adequately described by traditional soil survey tools. Traditional methods of soil sampling and analyses provide detailed information on the soil at specific locations, but are limited in number, volume, and spatial coverage. At field and landscape scales, characterizing spatial and temporal variations in soil properties is prohibitively time-consuming, expensive, and impractical using traditional point-sampling methods alone. Remote-sensing (e.g., satellite images, aerial photos) can provide excellent spatial coverage, but measurements are mostly indirect and shallow (typically limited to top 5–6 cm), and resolution is generally too coarse to characterize the spatial variability of soil properties at intermediate (field and landscape) scales. Because of these limitations, proximal soil sensing is being increasingly used to fill in the data gap that exists between high resolution point and the lower resolution remote-sensing data at field and landscape scales. Proximal soil sensing has been defined as a sub-discipline of soil science that includes the study of soil phenomena across spatial scales. In this chapter, descriptions are provided for different types of proximal sensing tools (i.e. near-surface geophysical methods) that can be used to map soil attributes of importance for agriculture and natural resource management.

Technical Abstract: Proximal soil sensing (i.e. near-surface geophysical methods) are used to study soil phenomena across spatial scales. Geophysical methods exploit contrasts in physical properties (dielectric permittivity, apparent electrical conductivity or resistivity, magnetic susceptibility) to indirectly measure, profile, and monitor differences in physico-chemical soil properties, locate structural boundaries, and characterize soil patterns and features. Surface geophysical methods include: electrical, electromagnetic, gravity, ground-penetrating radar, magnetic, seismic, self-potential, etc. The three most commonly used geophysical methods in soils and agriculture are electromagnetic induction (EMI), electrical resistivity (ER), and ground-penetrating radar (GPR) Initially used to assess soil salinity, the use of ER and EMI methods greatly expanded in agriculture with the development of precision agriculture in the 1990s. Since the late 1970s, GPR has been used extensively as a quality control tool to improve soil property interpretations. Recent improvements in instrumentation, computational capabilities, data processing, interpretative and display methods, and integration with other technologies (e.g., global positioning systems (GPS)) have increased the use of these and other geophysical methods in soils.