Degradation kinetics of biochar from pyrolysis and hydrothermal carbonization in temperate soils

• Published in: Plant and soil Vol. 372; no. 1/2; pp. 375 - 387
• Main Authors: Bai, Mo, Wilske, Burkhard, Buegger, Franz, Esperschütz, Jürgen, Kammann, Claudia Irene, Eckhardt, Christian, Koestler, Martin, Kraft, Philipp, Bach, Martin, Frede, Hans-Georg, Breuer, Lutz
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01.11.2013; Springer Netherlands; Springer Nature B.V
• Subjects: Agricultural soils; Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Biochar; Biodegradation; Biological and medical sciences; Biomedical and Life Sciences; Carbon; Carbon dioxide; Charcoal; Ecology; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Grassland soils; Kinetics; Life Sciences; Mineralization; Miscanthus; Organic carbon; Organic soils; Other nutrients. Amendments. Solid and liquid wastes. Sludges and slurries; Plant Physiology; Plant Sciences; Pyrolysis; Raw materials; Regular Article; Sandy loam soils; Soil biochemistry; Soil chemistry; Soil degradation; Soil microorganisms; Soil science; Soil Science & Conservation; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Soils; Temperature effects; Germany; Biodegradation; Char; HTC; Soil amendment; CO; efflux; Recalcitrant carbon; Pyrolysis; Carbon dioxide; Biochar; Temperate zone; Soil management; Carbon isotopes; Carbonization; Soils; Amendment; Stable isotopes; Kinetics; Soil plant relation
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-013-1745-6

Background and Aims Estimates of biochar residence times in soils range over three orders of magnitude. We present the first direct comparison between the biodegradation of a char from hydrothermal carbonization (htcBC) and pyrolysis (pyrBC) with high temporal resolution. Methods Mineralization of the biochars and their shared Miscanthus feedstock in three soils was determined directly by the ¹³CO₂ efflux using a novel method incorporating wavelength scanned cavity ring-down spectroscopy. Biochar half-life (t ½ ) was estimated with three empirical models. Results (1) The htcBC was readily biodegradable, whereas pyrBC was more recalcitrant. (2) Cumulative degradation of both biochars increased with soil organic carbon and nitrogen content. (3) The corrected Akaike information criterion (AIC C ) showed an overall preference for the double exponential model (DEM) reflecting a labile and a recalcitrant C-pool, over the first-order degradation model (FODM) and a logarithmic model. (4) The DEM resulted in t ½ ranging from 19.7-44.5, 0.7-2.1 and 0.8-1.3 years for pyrBC, pyrBC and feedstock, respectively. Conclusion The degradation was rather similar between feedstock and htcBC but one order of magnitude slower for pyrBC. The AIC C preferred FODM in two cases, where the DEM parameters indicated no distinction between a labile and recalcitrant carbon pool.