Does soil aging affect the N2O mitigation potential of biochar? A combined microcosm and field study

Publikations-Art

Zeitschriftenbeitrag (peer-reviewed)

Autoren

Hagemann, N., Harter, J., Kaldamukova, R., Guzman-Bustamante, I., Ruser, R., Graeff, S., Kappler, A., Behrens, S.

Erscheinungsjahr

2016

Veröffentlicht in

Global Change Biology, Bioenergy

DOI

10.1111/gcbb.12390

The application of biochar as a soil amendment to improve soil fertility has been suggested as
a tool to reduce soil-borne CO₂ and non-CO₂ greenhouse gas emissions, especially nitrous
oxide (N₂O). Both lab and field trials have demonstrated N₂O emission reduction by biochar
amendment, but the long-term effect (>1 year) has been questioned. Here we present results
of a combined microcosm and field study using a powdered beech wood biochar from slow
pyrolysis. The field experiment showed that both CO₂ and N₂O emissions were still
effectively reduced by biochar in the third year after application. However, biochar did not
influence the biomass yield of sunflower for biogas production (Helianthus annuus L.).
Biochar reduced bulk density and increased soil aeration and thus reduced the water filled
pore space (WFPS) in the field, but was also able to suppress N₂O emission in the
microcosms experiment conducted at constant WFPS. For both experiments, biochar had
limited impact on soil mineral nitrogen speciation, but it reduced the accumulation of nitrite
in the microcosms. Extraction of soil DNA and quantification of functional marker genes by
qPCR showed that biochar did not alter the abundance of nitrogen-transforming bacteria and
archaea in both field and microcosm experiments. In contradiction to previous experiments,