Zastosowanie techniki bliskiej podczerwieni do obliczania Siedliskowego Indeksu Glebowego

The research covered the application of near−infrared spectroscopy (NIR) to evaluate selected properties of forest soils, necessary to calculate the Soil Trophic Index (SIG). We analyzed 50 samples from 15 study plots located in the Miechów Forest Districts (S Poland). Five plots were established per each variant of the site conditions: upland deciduous forests (Lwyż), upland mixed deciduous forests (LMwyż) and upland mixed coniferous forests (BMwyż). On each plot soil pit was dug out and samples were taken from organic and three mineral (0−10 cm, 10−40 cm and 40−150 cm) horizons. NIR measurements were performed using Antharis II FT spectrometer to assess the following properties of forest soil: the content of organic carbon (Corg), total nitrogen (Nt), C:N ratio, the share of fine ø<0.02 mm) fraction, the content of base cations (S) and total acidity (Hh). Based on the 30 spectrums and the identified properties of soils, the calibration model was developed. The validation of the model was performed on independent set of 20 samples. Next, the SIG values were calculated on the basis of laboratory measurements and compared with the values obtained with NIR. Very good calibration results were observed for almost all soil properties (fig. 1, tab.). The highest correlation coefficient was obtained for the C:N ratio. During the validation, the nitrogen content was well estimated, as evidenced by the highest R²W values (tab.). The content of Corg, soil particles ø<0.02 mm and S were also relatively well estimated. The results suggest that the NIR technique can be successfully applied to evaluate the soil properties necessary to calculate SIG. The calculations are made at a much lower cost and in a very rapid way compared to laboratory methods.