Prediction of soil organic carbon using VIS-NIR spectroscopy: Application to Red Mediterranean soils from Croatia

Authors : Boško Miloš, Aleksandra Bensa

Pages : 365-373

Doi:10.18393/ejss.319208

View : 51 | Download : 9

Publication Date : 2017-10-01

Article Type : Research Paper

Abstract :The objectives of this research were: insert ignore into journalissuearticles values(i); to assess the accuracy of diffuse reflectance spectroscopy insert ignore into journalissuearticles values(DRS); in predicting the soil organic carbon insert ignore into journalissuearticles values(SOC); content, and insert ignore into journalissuearticles values(ii); determine the importance of wavelength ranges and specific wavelengths in the SOC prediction model. The reflectance spectra of a total of 424 topsoils insert ignore into journalissuearticles values(0-25 cm); samples were measured in a laboratory using a portable Terra Spec 4 Hi-Res Mineral Spectrometer with a wavelength range 350-2500 nm. Partial least squares regression insert ignore into journalissuearticles values(PLSR); with leave-one-out cross validation was used to develop calibration models for SOC prediction. The accuracy of the estimate determined by the coefficient of determination insert ignore into journalissuearticles values( R 2 );, the concordance correlation coefficient insert ignore into journalissuearticles values(ρc);, the ratio of performance to deviation insert ignore into journalissuearticles values(RPD);, the range error ratio insert ignore into journalissuearticles values(RER); and the root mean square error insert ignore into journalissuearticles values(RMSE); values of 0.83, 0.90, 2.42, 15.1 and 2.47 g C kg -1 respectively, indicated successful model for SOC prediction. The near infrared insert ignore into journalissuearticles values(NIR); and the short-wave infrared insert ignore into journalissuearticles values(SWIR); spectrums were more accurate than those in the visible insert ignore into journalissuearticles values(VIS); and short-wave near-infrared insert ignore into journalissuearticles values(SWNIR); spectral regions. The wavelengths contributing most to the prediction of SOC were at: 1925, 1915, 2170, 2315, 1875, 2260, 1910, 2380, 435, 1960, 2200, 1050, 1420, 1425 and 500 nm. This study has shown that VIS-NIR reflectance spectroscopy can be used as a rapid method for determining organic carbon content in the Red Mediterranean soils that can be sufficient for a rough screening. 
Keywords : Chemometrics, PLSR, Spectral regions, wavelengths

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