Imaging Spectrometry for Soil Applications

Imaging spectroscopy (IS) is a new technique that has attracted the attention of many workers in many disciplines including the soil science. Going from point to image spectrometry is not only a journey from micro to macro scales, but also a long stage that encounters problems such as dealing with data having a low signal-to-noise level, contamination of the atmosphere, large data sets, the BRDF effect and more. In this paper we attempt to explore the feasibility of IS for soil science first by reviewing the history of IS in general, and then pointing out the potential of reflectance spectroscopy for soil application in particular. We tried to understand why, although being promising, IS is not presently well developed in the soil sciences field and we provide several explanations and solutions for that. We also explore the difficulties in acquiring and processing IS data in general and for soil in particular. To illustrate the IS potentiality in soil science, we have gathered most of the authors who have worked with soil and IS technology, and provided their and other's case studies in this regard. Soil degradation (salinity, erosion, and deposition), merging IS with other remote sensing means, soil mapping and classification, soil genesis and formation, soil contamination, soil water content, and swelling soils are the issues discussed in this study. We review these case studies and analyze how IS technology can be pushed forward for soil science applications. We assume that education, exposing the technology to end-users, as well as, governmental involvement are the major factors that require attention in this venue. We also suggest that the IS data be provided to the end users as real reflectance and not as raw data. This is because converting the raw data into reflectance is a complicated stage that requires experience, knowledge, and specific infrastructures not available to many users. This stage stands as a barrier that impedes potential end-users, inhibiting workers from trying this technique for their needs. The paper ends with a general call to the soil science audience to extend the utilization of IS technique and compare the ability of the technique to a "giant" that still needs to wake up. We compare the evolution of the well-developed chemometric technique used to analyze soil properties in the laboratory with the "sleeping" IS technique. Keywords: Soil reflectance, Image Spectroscopy, Soil properties, Soil Applications,

JRC.H.5 - Rural, water and ecosystem resources