Spectral analysis as an extra method to soil type discrimination

M. Todorova1*, S. Atanassova2, M. Georgiev1, L. Pleshkuza1

1Department of Crop production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria,
2Department of Biochemistry, Microbiology and Physics, Faculty of Agriculture, Trakia University,
6000 Stara Zagora, Bulgaria

(Manuscript received 18 February 2020; accepted for publication 25 April 2020)

Abstract. The purpose of the study was to test near infrared soil spectra as an extra method for three soil types (Fluvisols, Vertisols and Solonchaks) discrimination from different regions of South Bulgaria. The diffuse reflectance spectra of 177 soil samples (from the 0-20cm layers): 50 samples of Fluvisols soil type, 78 samples of Vertisols soil type and 48 samples of Solonchaks soil type were obtained using a Spectrum NIRQuest (OceanOptics, Inc.) working within the range from 900 to 1700 nm. Soft independent modelling of class analogy (SIMCA) was performed to classify samples according to their taxonomic classes. The results obtained showed that the soil samples are separated accurately according to their soil type based on their spectral information. All this could be used in the future studies related to the application of the NIRS method as a qualitative or quantitative method for soil analysis and also for the purposes of precision farming.