Biochar impacts on nutrient dynamics in a subtropical grassland soil - Part 2. Greenhouse gas emissions

Authors: LU, YANYAN - University Of Florida; SILVEIRA, MARIA - University Of Florida; Cavigelli, Michel; O'CONNOR, GEORGE - University Of Florida; VENDRAMINI, JOAO - University Of Florida; ERICKSON, JOHN - University Of Florida; LI, YUNCONG - University Of Florida

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2020
Publication Date: 9/29/2020
Citation: Lu, Y., Silveira, M.L., Cavigelli, M.A., O'Connor, G.A., Vendramini, J.M., Erickson, J., Li, Y. 2020. Biochar impacts on nutrient dynamics in a subtropical grassland soil - Part 2. Greenhouse gas emissions. Journal of Environmental Quality. 49:1421-1434. https://doi.org/10.1002/jeq2.20141.
DOI: https://doi.org/10.1002/jeq2.20141

Interpretive Summary: Land application of biochar reportedly provides many benefits including reduced risk of nutrient transport and mitigation of greenhouse gas emissions, but additional field validation is needed. Researchers evaluated the impacts of biochar co-applied with either biosolids or inorganic fertilizer on emissions of the greenhouse gases carbon dioxide, nitrous oxide, and methane from a subtropical grassland. Results of the 3-yr field study demonstrated no differences in emissions of carbon dioxide and methane, but annual and cumulative nitrous oxide emissions were greater with biosolids than with inorganic fertilizer application. Biochar reduced carbon dioxide emissions modestly but had no effects on nitrous oxide and methane emissions. Results indicate limited benefit of this biochar on greenhouse gas emissions. These results will be of interest to policy makers, farm managers and others concerned about impacts of farming practices on global climate change.

Technical Abstract: Land application of biochar reportedly provides many benefits including reduced risk of nutrient transport, greenhouse gas (GHG) emission mitigation and increased soil C storage, but additional field validation is needed. This is a 2-part paper designed to evaluate the effectiveness of biochar in controlling the lability of nutrients in agricultural land. Part I was focused on the impacts of biochar nutrient management on water quality. This study is designed to evaluate the impacts of biochar co-applied with various N and P sources on GHG fluxes from a subtropical grassland. Nutrients (inorganic fertilizer and aerobically-digested Class B biosolids) were surface-applied at a rate of 160 kg plant available N ha-1 yr-1 with or without biochar (applied at 20 Mg ha-1). Greenhouse gas (CO2, CH4, and N2O) fluxes were assessed using static chambers, and varied significantly, both temporally and with treatments. GHG fluxes ranged from 1247 to 23160, -0.7 to 42, and -1.4 to 376 mg m-2 d-1 for CO2, N2O, and CH4, respectively. Results of the 3-yr field study demonstrated strong seasonal variability associated with GHG emissions. Nutrient source had no effect on soil CO2 and CH2 emissions, but annual and cumulative (3-yr) N2O emissions increased with biosolids (8 kg N2O ha-1 yr-1) compared with inorganic fertilizer (5 kg N2O ha-1 yr-1) application. Data suggested that environmental conditions played a more important role on GHG fluxes than nutrient additions. Biochar reduced CO2 emissions modestly (<9%), but had no effects on N2O and CH4 emissions.