Exploratory study of infrared spectral signatures of a range of forest, agricultural and artificialized soils from the North-East of France

Abstract

International audienceArtificialized soils encompass a large diversity depending both on the environmental conditions and the history of land uses. Their study requires to develop an approach to compare and classify them. Vibrational spectroscopies are used in soil science to collect rapid and cost-effective molecular information about inorganic and organic soil constituents [1]. Coupled with chemometrics approaches (e.g. [2]), they can be used to estimate some properties and/or to classify soils [3]. This study aims at exploring the potential of mid-infrared spectroscopy (i) to differentiate soils depending on past land uses, (ii) to propose a soil typology and (iii) to define markers of human activities.A set of 150 surface soil samples from the North-East of France was selected, including agricultural and forest soils developed on various bedrocks and soils impacted by iron and glass industry, mining, charcoal production or old human settlements. Mid-infrared analyses were run in diffuse reflectance mode. An exploratory study was performed on the preprocessed spectra using ascending hierarchical classification and principal component analysis. Studied soils can be distinguished based on their mineralogical composition (carbonates, clays) and, to a lesser extent, on the presence of organic compounds (Fig1). However, changes related to old settlements, mining or charcoal production were more difficult to discriminate. This could be improved by coupling several spectroscopic analyses providing complementary information on the samples