Agro-environmental characterization of semi-arid Mediterranean soils using NIR reflection and mid-IR-attenuated total reflection spectroscopies

The use of infrared spectroscopy to perform an agro-environmental soil characterization in areas with high degradation risks, like the Mediterranean semi-arid environments, has been evaluated using diffuse reflection near infrared spectroscopy (NIR) and attenuated total reflection middle infrared spectroscopy (ATR-FTIR). Soils from calcareous substratum, beneath three management types (organic, conventional and natural vegetation) have been studied. Factors like the parent material, the depth of sampling and the slope position have been considered. Although the parent material seems to be the factor most influencing the infrared spectral pattern, especially in the mid-IR region, soils under different management practices can also be differentiated on the basis of their spectral characteristics. It is interesting to note that the differences between the soils under conventional practices and after more than twenty years of organic management are much more evident for soils developed on marls than for those developed on colluvial limestones. This can be attributed to less degradation of the latter type of soils even under conventional management due to their more evolved nature and resilience. Considering the results, a combination of NIR and mid-IR spectroscopy could improve soil classification performance, being especially useful for the fast identification of those soils suffering severe degradation.