Vibrational spectroscopy and Aquaphotomics holistic approach to determine chemical compounds related to sustainability in soil profiles

Abstract Advances in laboratory instrumentation and chemometrics provide alternatives to traditional methods of conducting soil chemical analysis. One of these is infrared diffuse reflectance spectroscopy in the near-infrared spectral range. The usefulness of Near Infra-Red Spectroscopy (NIRS), as a nondestructive, quick, and low-cost method to provide scientific expertise on a large scale, has been proved in several fields of applications. Soil samples were collected from alluvial and loess-sampling sites in the North Sardinia, where precipitation, climate, and land use conditions can be very similar. A total of 95 soil samples were collected from three study areas (Berchidda, Arborea, and Ottava). The C and N contents in the soil samples were determined using an elemental analyzer and spectra of soil samples were collected using microNIR 1700 spectrometer. Data processing was carried out using the NIR region of the first water overtone. PLSR applied for calibration of C and N content, allowed the quantitative determination of both elements with good performances. Areas with low Soil Organic Carbon (SOC) can be identified and mapped, thus facilitating the development of both remediation strategies in terms of application of fertilization, environmental protection, and methods for modeling soil properties with great potential for diagnosing the nutrient deficiency and assessing the risk of soil parameters on the environment. The Aquaphotomics approach was able to associate one specific water absorption spectral pattern (WASP) to each studied area, detecting great differences in particular between the Berchidda zone and the other two sampling areas (Arborea, Ottava).