In Situ Persistence and Migration of Biochar Carbon and Its Impact on Native Carbon Emission in Contrasting Soils under Managed Temperate Pastures

Bhupinder Pal Singh; Yunying Fang; Mark Boersma; Damian Collins; Lukas Van Zwieten; Lynne M Macdonald

doi:10.1371/journal.pone.0141560

In Situ Persistence and Migration of Biochar Carbon and Its Impact on Native Carbon Emission in Contrasting Soils under Managed Temperate Pastures

PLoS One. 2015 Oct 28;10(10):e0141560. doi: 10.1371/journal.pone.0141560. eCollection 2015.

Authors

Bhupinder Pal Singh¹, Yunying Fang¹, Mark Boersma², Damian Collins¹, Lukas Van Zwieten³, Lynne M Macdonald⁴

Affiliations

¹ NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Menangle, NSW, 2568, Australia.
² University of Tasmania, Tasmanian Institute of Agriculture, Burnie, Tasmania, 7320, Australia.
³ NSW Department of Primary Industries, Wollongbar Primary Industries Institute, Wollongbar, NSW, 2477, Australia.
⁴ CSIRO Agriculture, Glen Osmond, South Australia, 5064, Australia.

Abstract

Pyrogenic carbon (PyC) is an important component of the global soil carbon (C) pool, but its fate, persistence, and loss dynamics in contrasting soils and environments under planted field conditions are poorly understood. To fill this knowledge gap, a 13C-labelled biochar, as a surrogate material for PyC, produced from Eucalyptus saligna by slow pyrolysis (450°C; δ13C -36.7‰) was surface (0-10 cm) applied in C3 dominated temperate pasture systems across Arenosol, Cambisol and Ferralsol. The results show a low proportion of the applied biochar-C mineralised over 12 months in a relatively clay- and C-poor Arenosol (i.e., 2.0% loss via mineralisation), followed by a clay- and C-rich Cambisol (4.6%), and clay-, C- and earthworm-rich Ferralsol (7.0%). The biochar-C mean residence time (MRT), estimated by different models, varied between 44-1079 (Arenosol), 18-172 (Cambisol), and 11-29 (Ferralsol) years, with the shorter MRT estimated by a one-pool exponential and the longer MRT by an infinite-pool power or a two-pool exponential model. The two-pool model was best fitted to biochar-C mineralisation. The biochar-C recovery in the 12-30 cm soil layer varied from between 1.2% (Arenosol), 2.5-2.7% (Cambisol) and 13.8-15.7% (Ferralsol) of the applied biochar-C after 8-12 months. There was a further migration of biochar-C below the 50-cm depth in the Arenosol, as the combined biochar-C recovery in the mineralised pool and soil profile (up to 30 or 50 cm) was 82%, in contrast to 101% in the Cambisol and 104% in the Ferralsol after 12 months. These results indicate that the downward migration of biochar-C was greatest in the Arenosol (cf. Cambisol and Ferralsol). Cumulative CO2-C emission from native soil-plant sources was lower (p <0.10) in the biochar-amended vs. non-amended Ferralsol. This field-based study shows that the downward migration of biochar-C exceeded its loss via mineralisation in the Arenosol and Ferralsol, but not in the Cambisol. It is thus important to understand biochar-soil interactions to maximise long-term biochar C sequestration potential in planted soil systems.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Australia
Carbon / chemistry*
Charcoal / chemistry*
Soil / chemistry*
Temperature*

Substances

Soil
biochar
Charcoal
Carbon

Grants and funding

This research was funded to BPS, MB, LVZ, and LMM by the Australian Department of Agriculture (under their Biochar Capacity Building Program). This research was also funded to BPS by the NSW Department of Primary Industries and to MB by the University of Tasmania. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.