A Review of Geophysical Methods for Soil Structure Characterization

Abstract

The growing interest in the maintenance of favorable soil structure is largely motivated by its central role in plant growth, soil ecological functioning, and impacts on surface water and energy fluxes. Soil structure pertains to the spatial arrangement of voids and solid constituents, their aggregation, and mechanical state. As a fragile product of soil biological activity that includes invisible ingredients (mechanical and ecological states), soil structure is difficult to define rigorously, and measurements of relevant metrics often rely on core samples or on episodic point measurements. The presence of soil structure has not yet been explicitly incorporated in climate and Earth systems models, partially due to incomplete methodological means to characterize it at relevant scales and to parameterize it in spatially extensive models. We seek to review the potential of harnessing geophysical methods to fill the scale gap in characterization of soil structure directly (via impact of soil pores, transport, and mechanical properties on geophysical signals) or indirectly by measurement of surrogate variables (wetness and rates of drainage). We review basic aspects of soil structure and challenges of characterization across spatial and temporal scales and how geophysical methods could be used for the task. Additionally, we propose the use of geophysical models, inversion techniques, and combination of geophysical methods for extracting soil structure information at previously unexplored spatial and temporal scales.

La magnetometría como alternativa en la búsqueda de aguas subterráneas. El caso de la cuenca baja del río Grijalva.

“…En particular, para este propósito existen los métodos gravimétricos y magnéticos, conocidos como métodos potenciales. Estos se aplican tanto en áreas urbanas como rurales (Henderson, 1992;Huizar-Álvarez et al, 1997;Flores-Márquez et al, 1998;López-Loera, 2014), o en sectores como la industria petrolera (Ndougsa-Mbarga et al, 2007), la explotación de recursos minerales, la agricultura, geotermia, geología, arqueología, forense y la hidrología (Silva, 1974;Allred et al, 2008;Robinson et al 2008;Reynolds, 2011;Alatorre-Zamora et al, 2015;Tinivella et al, 2013;Binley et al, 2015;Romero-Ruiz et al 2018;Florsch et al, 2019). De tal modo, la magnetometría es considerada un método versátil y de fácil operación que puede ser aplicado a distintos problemas de exploración del subsuelo (Ernstson, 2006).…”

“…La aplicación de los métodos geofísicos a la hidrología no es reciente, la hidrogeofísica, como disciplina de la geofísica para investigar procesos hidrológicos, se ha fortalecido en los últimos años debido a los avances y la disminución de costos en la tecnología e instrumentación (Hubbard & Rubin, 2005;Robinson et al, 2008). En los últimos años, desde la hidrogeofísica, el uso de métodos geofísicos ha estado enfocado en investigaciones hidrogeológicas, en el conocimiento de problemas ambientales e infiltración de contaminantes en el suelo, en el mapeo de las características del subsuelo, en la variabilidad espacial y temporal de la humedad del suelo, en el funcionamiento biogeoquímico del sistema agua-suelo, en el estudio de procesos hidrológicos, y en las interacciones de las aguas subterráneas con las superficiales y costeras (Hubbard & Rubin, 2005;Vereecken et al, 2006;Robinson et al, 2008;Kirsch, 2009;Binley et al, 2015;Brocca et al, 2017;Romero-Ruiz et al, 2018;Florsch et al, 2019).…”

NMR relaxation times for soil texture estimation in the laboratory: A comparison to the laser diffraction and sieve–pipette methods

“…Geophysical methods have been used extensively to characterize soils (e.g., Binley et al, 2015; Romero‐Ruiz, Linde, Keller, & Or, 2018). These methods can be used in the field, many are non‐invasive (i.e., do not require soil samples or an augered profile) and the data can be collected relatively quickly.…”

Real-Time Electrical Resistivity Measurement and Mapping Platform of the Soils with an Autonomous Robot for Precision Farming Applications

“…However, this method has several difficulties and limitations such as high cost, time consuming, and insufficient data for huge farmlands. In this context, geophysical methods offer the chance to overcome some of the problems inherent in more conventional soil investigation techniques for soil structure characterization at larger spatial and temporal scales [8].…”

“…The measuring depth can be changed by changing the distance between the probes. larger spatial and temporal scales [8]. Soil is strongly correlated and can be quantified through the geoelectrical properties [9].…”