Application of ATR-FTIR spectrometry for express prediction of the organic matter properties of arable leached chernozem

Abstract

© 2020 International Multidisciplinary Scientific Geoconference. All rights reserved. In this work the possibility of express prediction of the content of organic carbon, total and hydrolysable nitrogen in leached chernozems by infrared spectrometry with attenuated total reflection sampling technique with minimal spectra processing was studied. The territory of study is a plot with a rugged topography (elevation changes up to 60 m) and severe erosion. In total, 50 samples were taken from the arable horizon (0-20 cm). The spectra were obtained in the range 4000-660 cm-1 with a spectral resolution – 4cm-1. Each sample was scanned three times, baseline correction was performed for each spectrum. From three replicates, average spectra were obtained, which then used for models development. In the studied samples, the organic carbon content ranged from 2.44% in eroded areas of the field to 5.55% in negative landforms. The variation of the property is average 18.7%. The total nitrogen content varied in the range of 0.04-0.44%, the variation of property was 25.0%. The average content of hydrolysable nitrogen is 100.45 ± 19.49 mg kg-1, which is 0.01% by weight of the soil. It was found that with simple spectral processing and the Beer's law linear regression method, the prediction of such important indicators for agrochemistry is slightly lower (r = 0.70-0.87) than can be found in other works, that use complex operations of digital data processing and difficult mathematical models. But to rapid assessment of soil properties it is possible to use the simple methods and models with an acceptable level of prediction. For express prediction the most effective ranges of spectra are the following: 1640-1550 cm-1 for organic C, 1640-1550 cm-1 for total N and 1640-1550 cm-1 for hydrolysable N