title: Biochar from sugarcane filtercake reduces soil CO2 emissions relative to raw residue and improves water retention and nutrient availability in a highly-weathered tropical soil.
abstract: In Brazil, the degradation of nutrient-poor Ferralsols limits productivity and drives agricultural expansion into pristine areas. However, returning agricultural residues to the soil in a stabilized form may offer opportunities for maintaining or improving soil quality, even under conditions that typically promote carbon loss. We examined the use of biochar made from filtercake (a byproduct of sugarcane processing) on the physicochemical properties of a cultivated tropical soil. Filtercake was pyrolyzed at 575°C for 3 h yielding a biochar with increased surface area and porosity compared to the raw filtercake. Filtercake biochar was primarily composed of aromatic carbon, with some residual cellulose and hemicellulose. In a three-week laboratory incubation, CO2 effluxes from a highly weathered Ferralsol soil amended with 5% biochar (dry weight, d.w.) were roughly four-fold higher than the soil-only control, but 23-fold lower than CO2 effluxes from soil amended with 5% (d.w.) raw filtercake. We also applied vinasse, a carbon-rich liquid waste from bioethanol production typically utilized as a fertilizer on sugarcane soils, to filtercake- and biochar-amended soils. Total CO2 efflux from the biochar-amended soil in response to vinasse application was only 5% of the efflux when vinasse was applied to soil amended with raw filtercake. Furthermore, mixtures of 5 or 10% biochar (d.w.) in this highly weathered tropical soil significantly increased water retention within the plant-available range and also improved nutrient availability. Accordingly, application of sugarcane filtercake as biochar, with or without vinasse application, may better satisfy soil management objectives than filtercake applied to soils in its raw form, and may help to build soil carbon stocks in sugarcane-cultivating regions.
authors.affiliation: Institute for Resources, Environment, and Sustainability, University of British Columbia (UBC), Vancouver, British Columbia, Canada.
authors.forename: Angela Joy
authors.initials: AJ
authors.lastname: Eykelbosh
authors.affiliation: Institute for Resources, Environment, and Sustainability, University of British Columbia (UBC), Vancouver, British Columbia, Canada; Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia (UBC), Vancouver, British Columbia, Canada.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Johnson
authors.affiliation: Faculdade de Agronomia, Medicina Veterinária e Zootecnia (FAMEV), Universidade Federal de Mato Grosso, Cuiabaá, Mato Grosso, Brazil.
authors.forename: Edmar
authors.initials: E
authors.lastname: Santos de Queiroz
authors.affiliation: Instituto de Física, Universidade Federal de Mato Grosso, Cuiabá, Mato Grosso, Brazil.
authors.forename: Higo José
authors.initials: HJ
authors.lastname: Dalmagro
authors.affiliation: Faculdade de Agronomia, Medicina Veterinária e Zootecnia (FAMEV), Universidade Federal de Mato Grosso, Cuiabaá, Mato Grosso, Brazil.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Guimarães Couto
mesh_terms: D001938:Brazil; D002245:Carbon Dioxide / Q000032:analysis / Q000737:chemistry*; D002606:Charcoal; D031786:Saccharum; D012987:Soil / Q000737:chemistry*; D014867:Water
chemical_list: D012987:Soil; C540010:biochar; D014867:Water; D002245:Carbon Dioxide; D002606:Charcoal