Quantity of hydrophobic functional CH-groups – decisive for soil water repellency caused by digestate amendment
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| Authors: | A. Voelkner1, D. Holthusen1, R. Ellerbrock2, R. Horn1 1Institute of Plant Nutrition and Soil Science, University of Kiel, Hermann-Rodewald 2, 24118 Kiel, Germany 2Institute of Soil Landscape Research, Leibnitz Centre for Agricultural Landscape Research, Eberswalder 84, 15374 Müncheberg, Germany |
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| Abstract : | A b s t r a c t. Anaerobic digestates are used as organic fertilizers; however, they are suspected to interfere negatively with soils. To investigate the relevance of the anaerobic digestates composition on potential wettability and contact angle of the soil, we mixed in a laboratory experiment 30 m³ ha-1 of anaerobic digestates derived from mechanically pre-treated substrates from maizeand sugar beet with a homogenized Cambic Luvisol. Fourier trans-form infrared-spectra and diffuse reflectance infrared Fouriertransform-spectra of particle intact and finely ground soil-anaerobic digestates-mixtures were analyzed to determine the quantities of hydrophobic functional groups in the soil-anaerobic digestates-mixtures that are used here as an indicator for the potential hydrophobicity. The anaerobic digestates application increased the amount of hydrophobic functional groups of the mixtures and reduced the wettability of the soil. However, for intact particle samples an up to threefold higher amount of hydrophobic groups was found as compared to the finely ground ones, indicating a dilution effect of mechanical grinding on the effectivity of the organic matter that is presumably located as a coating on mineral soil particles. For the particle intact samples, the intensity of hydrophobic functional groups bands denoting hydrophobic brickstones in organic matter is indicative for the actual wettability of the soil-anaerobic digestates-mixtures |
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| Keywords : | anaerobic digestates, organic matter composition, Fourier transform infrared spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy | ||||||||||
| Language : | English | ||||||||||