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Abstract

There is overwhelming evidence for the long-term persistence of biochar in soil. However, the partitioning ofbiochar into light and heavy carbon (C) fractions and microbial biomass C (MBC), and the dynamics of C useefficiency (CUEE: net incorporation of biochar into MBC per unit of biochar-C consumed, including microbialdeath and recycling of biochar-derived microbial metabolites) in planted soil systems are poorly understood. A13C-labelled wood biochar (δ13C: −36.7‰) was incorporated into topsoil (0–10 cm) in an Arenosol, Cambisoland Ferralsol under C3 dominated temperate pastures (δ13C: −25 to −27‰). The partitioning of biochar-C intothe various soil C pools and CUEE were measured at 4, 8 and 12 months. The results showed that 8.6–28.2% ofthe biochar-C in the top soils was distributed to the heavy fraction (HF) within 4 months, which increased to11.0–33.3% at 8 and 12 months. Biochar-C recovery in the HF was the highest in the Ferralsol (cf. Arenosol andCambisol), possibly due to greater interaction of biochar and biochar-derived microbial metabolites with soilminerals. Biochar significantly increased MBC across the three soils. Biochar-derived MBC ranged from 22 to93 mg C kg−1 soil over time (Arenosol E was 0.20–0.27 at 4 months, which decreased over time, possibly due to lowering of biochar-Cavailability to microbes. Further, although biochar-derived MBC was higher, biochar CUEE was lower in theFerralsol (cf. Arenosol and Cambisol), likely supported by higher microbial respiration and turnover, and lowerrecycling of microbial metabolites via greater organo-mineral interaction. Here, the study advanced our understandingof key C cycling processes, such as CUEE and the temporal fate of biochar-derived C in an organomineralfraction with relevance for biochar sequestration in contrasting soils under planted field conditions.

Item Type:	Article
Authors/Creators:	Fang, Y and Singh, BP and Luo, Y and Boersma, M and Van Zwieten, L
Keywords:	pyrogenic carbon, carbon use efficiency, biochar, mineralisation, stabilisation
Journal or Publication Title:	Soil Biology and Biochemistry
Publisher:	Pergamon-Elsevier Science Ltd
ISSN:	0038-0717
DOI / ID Number:	10.1016/j.soilbio.2017.10.042
Copyright Information:	Crown Copyright © 2017 Published by Elsevier Ltd.
Related URLs:	Google Scholar: Boersma, M UTAS Profile: Boersma, M
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