An intensive field campaign was performed from April to June 2009 to assess the effect of biochar
amendment on the emission of soil-borne GHGs from a sub-tropical pasture on acidic ferrosol. Over the whole measurement period high emissions of N2O and high fluxes of CO2 could be observed, whereas a net uptake of CH4 was measured. Only small differences in the fluxes of N2O and CH4 from the biochar amended plots (35.33 ± 4.83 ?g N2O-N/m2/h, -6.76 ± 0.20 ?g CH4 -C/m2/h) vs. the control plots (31.08 ± 3.50 ?g N2O-N/m2/h, -7.30 ± 0.19 ?g CH4 -C/m2/h) could be observed, while there was no significant difference in the fluxes of CO2. However, it could be observed that N2O emissions were significantly lower from the biochar amended plots during periods with low emission rates (< 50 ?g N2O-N/m2/h). Only during an extremely high emission event following heavy rainfall N2O emissions from the biochar amended plots were higher than from the control plots. Our results demonstrate that pastures on ferrosols in Northern NSW are a significant source of GHG and that the amendment of biochar can alter those emissions. However, more field and laboratory incubation studies covering prolonged observation periods are needed to clarify the impact of biochar amendment on soil microbial processes and the emission of soil-borne GHGs.
