The objectives of this research were: (i) to assess the accuracy of diffuse reflectance spectroscopy (DRS) in predicting the soil organic carbon (SOC) content, and (ii) determine the importance of wavelength ranges and specific wavelengths in the SOC prediction model. The reflectance spectra of a total of 424 topsoils (0-25 cm) samples were measured in a laboratory using a portable Terra Spec 4 HiRes Mineral Spectrometer with a wavelength range 350-2500 nm. Partial least squares regression (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 (R 2), the concordance correlation coefficient (ρc), the ratio of performance to deviation (RPD), the range error ratio (RER) and the root mean square error (RMSE) values of 0.83, 0.90, 2.22, 14.2 and 2.47 g C kg-1 respectively, indicated good model for SOC prediction. The near infrared (NIR) and the shortwave infrared (SWIR) spectrums were more accurate than those in the visible (VIS) and shortwave near-infrared (SWNIR) spectral regions. The wavelengths contributing most to the
The objective of the study was to characterize spatial pattern of soil properties (CaCO3, soil organic carbon, P2O5, K2O, and clay content) using fractal concept. Total of 141 topsoil samples (0-30 cm) were collected on 1850 ha in karst polje (Petrovo polje, Croatia) and analyzed for listed soil properties. The semi-variogram method was used to estimate fractal dimension (D) value which was performed from both of isotropic and anisotropic perspective. The D value of soil properties ranged between 1.76 to 1.97, showing a domination of the short-range variations. The SOC and K2O fractal D values 1.79 and 1.76 respectively, exhibited a spatial continuity at the entire analysed range of the scale. The D value for P2O5 (1.97) showed a nearly total absence of the spatial structure at all scales. The CaCO3 and clay content indicated a multifractal behavior mainly attributed to effects of alluviation, differences in geology and its spatial changes and transitions. The results of anisotropic analysis of soil properties pattern have showed strong relations with directions and partial self-similarity over limited ranges of scales defined by scale-break. Finally, our results showed that fractal analysis can be used as a appropriate tool for the characterization of spatial pattern irregularities of soil properties and detection of soil forming factors that cause it.
The objectives of this study were to (i) evaluate the ability of Vis-NIR spectroscopy to predict soil organic carbon (SOC) and CaCO 3 content in the heterogeneous agricultural soils from Dalmatia, Croatia and (ii) to compare the performance of two multivariate calibration techniques: partial least square regression (PLSR) and support vector machine regression (SVMR). The reflectance spectra of a total of 250 top-soils (0-25 cm) samples were collected in the laboratory using a portable Terra Spec 4 HiRes Mineral Spectrometer with a wavelength range 350-2500 nm. The coefficient of determination (R 2), the residual prediction deviation (RPD) and the root mean square error (RMSE) were used for the model evaluation. The CaCO 3 prediction derived by PLSR and SVMR with R 2 (0.86 and 0.88) and RPD (2.67 and 2.82), respectively are considered good prediction models. The SOC prediction with SVMR (R 2 0.84 and RPD 2.43) indicates good prediction and approximate quantitative prediction with PLSR with R 2 of 0.78 and RPD of 1.94. Our results showed that (i) CaCO 3 and SOC estimations were obtained with acceptable accuracy using Vis-NIR spectroscopy, (ii) the SVMR method produced more accurate estimations of selected soil properties compared to PLSR, and (iii) Vis-NIR spectroscopy, in combination with SWMR can be recommended as a rapid and inexpensive method for screening of the CaCO 3 and SOC content.
The aims of this study were: (i) to determine concentrations of heavy metals (HMs): Cd, Cu, Pb and Zn in terraced soils on flysch deposits of Kaštela Bay coastal area, Croatia, (ii) to define their possible sources and (iii) to compare concentrations of HMs among different land use types: olive groves, vineyards and abandoned agricultural land (grassland). In a total of 26 topsoil samples (0-25 cm) were analysed for pH, carbonates, organic carbon, K 2 O, P 2 O 5 , texture and concentrations of the HMs. The elements were extracted with aqua regia and determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The following mean values of Cd, Cu, Pb and Zn concentrations were 0.39, 46.5, 15.8 and 51.4 mg/kg, respectively. The principal component analysis (PCA) and the correlation matrix (CM) revealed weak relationship of HMs with soil properties and strong similarity among Cd, Pb and Zn concentrations indicating its common origin, controlled by different anthropogenic activity. The Cu poorly correlated with all other metals that point to its different origin-application of copper-based fungicide. The mean concentrations of Cd, Pb and Zn in vineyards, olive groves and grasslands were not statistically significant different in relation to land use types. The Cu concentrations in vineyards were significantly higher compared to other land use types.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.