Sensing technologies for characterizing and monitoring soil functions: A review

Soils perform multiple functions that contribute to human survival and well-being. However, we often focus on soil to produce food and fiber and unsustainable management has accelerated its degradation, jeopardizing the successful delivery of its multiple functions. To explore the full potential of the soil in delivering multiple functions, a deep understanding of its behavior and variability in space and time is needed. Direct measurement of these soil functions is challenging. Sensing technologies (i.e., laboratory spectroscopy, and proximal and remote sensing) can provide reliable information on soil's variability at different spatial and temporal scales, which can be of paramount importance to studying soil functionality. As there is a lack of a comprehensive review describing the possibilities of sensing technologies for providing reliable soil data to assist soil functional assessments, this review presents evidence on the applicability of sensing technologies. Among the sensing technologies, laboratory spectroscopy has been found as a global tool that can characterize a suite of soil physical, chemical and biological soil properties accurately. Proximal sensing with a wide range of available sensors is practical for field soil characterization. Remote sensing, in turn, has been demonstrated to be effective in the monitoring of soils over space and time. Thus, sensing technologies can contribute to assessing soil functions at local, regional, and global scales. Their integration with data from the field or from process-based simulation is needed when aiming for a better understanding of processes that contribute to delivering key services for human welfare.