Biochar decreases dissolved organic carbon but not nitrate leaching in relation to vinasse application in a Brazilian sugarcane soil

• Published in: Journal of environmental management Vol. 149; pp. 9 - 16
• Main Authors: Eykelbosh, Angela Joy, Johnson, Mark S., Couto, Eduardo Guimarães
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-02-2015; Academic Press Ltd
• Subjects: Agriculture - methods; Analysis of Variance; Biochar; Brazil; Carbon; Carbon - analysis; Carbon emissions; Charcoal - chemistry; Dissolution; Dissolved organic carbon; Environmental management; Eutrophication; Fluorescence; Fluxes; Leaching; Nitrate; Nitrates; Nitrates - analysis; Saccharum; Soil (material); Soil - chemistry; Soil Pollutants - analysis; Soils; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Tropical zones; Vinasse; Waste Products - analysis; Water Movements; Water Quality; Dissolved organic carbon; Nitrate; Biochar; Leaching
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2014.09.033

Sugarcane cultivation is associated with catchment-wide impacts related to application of vinasse, a nutrient-dense effluent with high eutrophication potential. We evaluated the potential for biochar (charcoal produced from pyrolyzed filtercake) to mitigate carbon and nutrient leaching in a cultivated Brazilian Ferralsol after vinasse application.
Twelve soil columns (soil alone [S], soil with vinasse [SV], soil with vinasse and biochar [SVB], and soil with biochar [SB]) were flushed with water and then treated with water or vinasse. Samples collected via vacuum filtration were examined via UV–Vis and fluorescence spectroscopy.
Biochar attenuated dissolved organic carbon (DOC) leaching in soil (S vs. SB) as well as in relation to vinasse application (SV vs. SVB). Biochar-amended soil preferentially retained high-molecular weight, humic-like DOC species, as revealed by fluorescence spectroscopy and optical indices, but did not retain low-weight amino acid-like species. Vinasse application also increased total NO3− flux, which may have been exacerbated by biochar co-application.
Vinasse treatment strongly affects carbon and NO3− fluxes in this tropical soil. Biochar attenuated DOC leaching, likely through stabilization of complex compounds already present in soil, but did not lessen NO3− fluxes. Thus, biochar amendments in vinasse application areas may decrease carbon leaching.
•Filtercake biochar attenuated DOC leaching in untreated and vinasse-treated soil.•Fluorescence spectroscopy revealed preferential retention of humic-like DOC species.•Biochar may have exacerbated NO3− leaching from vinasse application.•Biochar may help stabilize DOC in amended, cultivated soil and prevent leaching.