Contribution of organic amendments to soil organic matter detected by thermogravimetry |
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| Authors: | David Tokarski Ji?í Ku?erík Karsten Kalbitz Michael Scott Demyan Ines Merbach Dietmar Barkusky Joerg Ruehlmann Christian Siewert |
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| Institution: | 1. LKS-Landwirtschaftliche Kommunikations- und Servicegesellschaft mbH, Niederwiesa, Germany;2. Dresden University of Technology, Institute of Soil Science and Site Ecology, Tharandt, Germany;3. Brno University of Technology, Institute of Chemistry and Technology of Environmental Protection, Brno, Czech Republic;4. The Ohio State University, School of Environment and Natural Resources, Columbus, Ohio, USA;5. Helmholtz-Centre for Environmental Research–UFZ, Department Community Ecology-Experimental research station, Bad Lauchst?dt, Germany;6. Leibniz Centre for Agricultural Landscape Research (ZALF), Agricultural Landscape Data Centre, Research Station, Müncheberg, Germany;7. IGZ—Leibniz Institute of Vegetable and Ornamental Crops, Grossbeeren, Germany;8. Technical University Berlin, Institute of Ecology, Chair of Soil Conservation, Berlin, Germany |
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| Abstract: | Sustainable soil management requires reliable and accurate monitoring of changes in soil organic matter (SOM). However, despite the development of improved analytical techniques during the last decades, there are still limits in the detection of small changes in soil organic carbon content and SOM composition. This study focused on the detection of such changes under laboratory conditions by adding different organic amendments to soils. The model experiments consisted of artificially mixing soil samples from non‐fertilized plots of three German long‐term agricultural experiments in Bad Lauchstädt (silty loam), Grossbeeren (silty sand), and Müncheberg (loamy sand) with straw, farmyard manure, sheep faeces, and charcoal in quantities from 3 to 180 t ha?1 each. In these mixtures we determined the organic carbon contents by elemental analysis and by thermal mass losses (TML) determined by thermogravimetry. The results confirmed the higher reliability of elemental analysis compared to TML for organic carbon content determination. The sensitivity of both methods was not sufficient to detect the changes in organic carbon content caused by small quantities of organic amendments (3 t ha?1 or 0.1–0.4 g C kg?1 soil). In the case of elemental analysis, the detectability of changes in carbon content increased with quantities of added amendments, but the method could not distinguish different types of organic amendments. On the contrary, the based on analysis of degradation temperatures, the TML allowed this discrimination together with their quantitative analysis. For example, added charcoal was not visible in TML from 320 to 330°C, which is used for carbon content determination. However, increasing quantities of charcoal were reflected in a higher TML around 520°C. Furthermore, differences between measured (with TML110–550) and predicted mass loss on ignition using both organic carbon (with TML330) and clay contents (with TML140) were confirmed as a suitable indicator for detection of organic amendments in different types of soils. We conclude that thermogravimetry enables the sensitive detection of organic fertilizers and organic amendments in soils under arable land use. |
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| Keywords: | elemental analysis fingerprinting model experiments soil organic carbon thermal decay dynamics |
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