Influence of Soil Type on Determination of Soil Organic Carbon by Near Infrared Reflectance Spectroscopy

M. Todorova

Abstract: The objective of this study was to investigate the influence of soil type on determination of soil organic carbon content by near infrared reflectance spectroscopy.
A total of 191 soil samples of Vertisols, Chernozems, Fluvisols and Luvisols, were taken from 0 – 20 and 40 – 60 cm layer. The organic carbon content was determined by Tyurin method. Soil’s spectra were collected using NIRGun, FANTEC, Japan, spectrophotometer within the range of 600 – 1100 nm. Calibration equations for determination of soil organic C content were derived by PLS. Separated calibration equations for determination of organic carbon content were obtained for each soil units. The accuracy of NIR predictions for quantitative analysis of soil organic carbon was significantly improved by stratification of samples based on soil type and spectral similarity. For example, for set samples of both Vertisols and Fluvisols R were 0.94, RPD for validation were 3.2. The ratio of the standard variation of the reference data to the standart error of prediction using total calibration models with all soil samples was lower, RPD = 2.0.

Keywords: near infrared spectroscopy; nondestructive method; organic carbon; soil type

Date published: 2017-02-13