Effect of biochar amendment on compost organic matter composition following aerobic composting of manure

Nikolas Hagemann; Edisson Subdiaga; Silvia Orsetti; José María de la Rosa; Heike Knicker; Hans-Peter Schmidt; Andreas Kappler; Sebastian Behrens

doi:10.1016/j.scitotenv.2017.08.161

Effect of biochar amendment on compost organic matter composition following aerobic composting of manure

Sci Total Environ. 2018 Feb 1:613-614:20-29. doi: 10.1016/j.scitotenv.2017.08.161. Epub 2017 Sep 9.

Authors

Nikolas Hagemann¹, Edisson Subdiaga², Silvia Orsetti², José María de la Rosa³, Heike Knicker³, Hans-Peter Schmidt⁴, Andreas Kappler⁵, Sebastian Behrens⁶

Affiliations

¹ Geomicrobiology, Center for Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen, Germany. Electronic address: nikolas.hagemann@agroscope.admin.ch.
² Environmental Mineralogy and Chemistry, Center for Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen, Germany.
³ Instituto de Recursos Naturales Agrobiología de Sevilla (IRNAS-CSIC), Av. Reina Mercedes, 10, 41012 Seville, Spain.
⁴ Ithaka Institute for Carbon Strategies, Ancienne Eglise 9, Arbaz 1974, Switzerland.
⁵ Geomicrobiology, Center for Applied Geoscience, University of Tuebingen, Sigwartstrasse 10, 72076 Tuebingen, Germany.
⁶ Department for Civil, Environmental, and Geo-Engineering, University of Minnesota, MN, United States; BioTechnology Institute, University of Minnesota, MN, United States. Electronic address: sbehrens@umn.edu.

PMID: 28892724
DOI: 10.1016/j.scitotenv.2017.08.161

Abstract

Biochar, a material defined as charred organic matter applied in agriculture, is suggested as a beneficial additive and bulking agent in composting. Biochar addition to the composting feedstock was shown to reduce greenhouse gas emissions and nutrient leaching during the composting process, and to result in a fertilizer and plant growth medium that is superior to non-amended composts. However, the impact of biochar on the quality and carbon speciation of the organic matter in bulk compost has so far not been the focus of systematic analyses, although these parameters are key to determine the long-term stability and carbon sequestration potential of biochar-amended composts in soil. In this study, we used different spectroscopic techniques to compare the organic carbon speciation of manure compost amended with three different biochars. A non-biochar-amended compost served as control. Based on Fourier-transformed infrared (FTIR) and ¹³C nuclear magnetic resonance (NMR) spectroscopy we did not observe any differences in carbon speciation of the bulk compost independent of biochar type, despite a change in the FTIR absorbance ratio 2925cm^-1/1034cm^-1, that is suggested as an indicator for compost maturity. Specific UV absorbance (SUVA) and emission-excitation matrixes (EEM) revealed minor differences in the extractable carbon fractions, which only accounted for ~2-3% of total organic carbon. Increased total organic carbon content of biochar-amended composts was only due to the addition of biochar-C and not enhanced preservation of compost feedstock-C. Our results suggest that biochars do not alter the carbon speciation in compost organic matter under conditions optimized for aerobic decomposition of compost feedstock. Considering the effects of biochar on compost nutrient retention, mitigation of greenhouse gas emissions and carbon sequestration, biochar addition during aerobic composting of manure might be an attractive strategy to produce a sustainable, slow release fertilizer.

Keywords: Amazonian Dark Earth; EEM; Electron exchange capacity; FTIR; Farmyard manure; Humic substances; NMR; Pyrogenic organic carbon; Sewages sludge char.