Sugarcane bagasse biochars impact respiration and greenhouse gas emissions from a latosol

Abstract

Purpose: A paucity in knowledge remains on the influence of biochar production temperature and the rate of application on greenhouse gas emissions from soil. The objective of this column experiment was to evaluate a biochar thermosequence by doses on CO2, N2O, and CH4 emissions from a latosol following nitrogen fertilizer application following a pre-incubation period. Materials and methods: Biochar was produced from sugarcane bagasse pyrolyzed at 300, 500, and 700 °C (BC 300, BC 500, and BC 700, respectively). Biochars were added to air-dried latosol columns at rates of 0, 0.5, 1, 2, 5, 10, and 15 % (w/w), and the water content was brought to 95 % of water-filled pore space (WFPS). The emissions from columns were tested on days 1, 3, 7, 15, and 30 following a 30-day pre-incubation. Results and discussion: All treatments showed a decrease in respiration across the study period. The higher doses of biochar of BC 300 and BC 700 resulted in significantly higher respiration than controls on days 15 and 30. Neither biochar dose nor temperature had a significant effect on CH4 emissions during the study period. Application of all biochars suppressed the emissions of N2O at all doses on days 1 and 3, compared to the control. N2O emissions from higher temperature biochar-amended soil at 2, 5, 10, and 15 % were greater than that from corresponding treatments of lower-temperature biochar-amended soil on days 15 and 30. Conclusions: Soil respiration and overall greenhouse gas emission from latosol increased with biochar dose and pyrolysis temperature in the 30-day study period due to increasing water retention facilitated by biochar. Careful consideration is needed when applying bagasse biochar as it changes N cycling and soil physical properties.