Utlização da espectroscopia de infravermelho e métodos quimiométricos em análise de amostras de solos

Abstract

The soil has become an increasingly necessary feature. To meet the demands of a society that multiplies exponentially is necessary the development of rapid procedures to assess their quality, allowing to make early decisions, reducing risks and losses. In this context, this work aims to propose a simple, fast and secure method for the analysis of quality parameters in soil samples through the use of infrared spectroscopy combined with multivariate analysis. To develop this project, soil samples were used from a farm explored in family arrangements, in the city of Irati, central-southern region of Paraná. These samples were submitted to the application of different dosages of limestone and applications methods. Samples were analyzed on a Varian 640-IR infrared spectrometer model of diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) in the spectral region of 400 - 4,000 cm-1. The spectra were analyzed with the aid of chemometric tools, done in the PLS Toolbox version 5.2 software (EIGENVECTOR..., 2009). Calibration models were developed in order to check the use of mid-infrared (MIR) spectra capability in quantifying physical and chemical parameters in soil samples. There were determination values for exchangeable aluminum (Al3+), exchangeable calcium (Ca2+), exchangeable magnesium (Mg2+) and pH (in CaCl2 solution), with R2 equals to 0.862, 0.852, 0.850 and 0.822, respectively, which enables - with few exceptions - their use in predictions to such parameters. They became, therefore, possible non-destructive and noninvasive analysis methods for soil samples in that region, with few sample preparation steps, replacing the wet methods routinely used.