title: Storage and stability of biochar-derived carbon and total organic carbon in relation to minerals in an acid forest soil of the Spanish Atlantic area.
abstract: Biochar can largely contribute to enhance organic carbon (OC) stocks in soil and improve soil quality in forest and agricultural lands. Its contribution depends on its recalcitrance, but also on its interactions with minerals and other organic compounds in soil. Thus, it is important to study the link between minerals, natural organic matter and biochar in soil. In this study, we investigated the incorporation of biochar-derived carbon (biochar-C) into various particle-size fractions with contrasting mineralogy and the effect of biochar on the storage of total OC in the particle-size fractions in an acid loamy soil under Pinus radiata (C3 type) in the Spanish Atlantic area. We compared plots amended with biochar produced from Miscanthus sp. (C4 type) with control plots (not amended). We separated sand-, silt-, and clay-size fractions in samples collected from 0 to 20-cm depth. In each fraction, we analyzed clay minerals, metallic oxides and oxy-hydroxides, total OC and biochar-C. The results showed that 51% of the biochar-C was in fractions <20μm one year after the application of biochar. Biochar-C stored in clay-size fractions (0.2-2μm, 0.05-0.2μm, <0.05μm) was only 14%. Even so, we observed that biochar-C increased with decreasing particle-size in clay-size fractions, as it occurred with the vermiculitic phases and metallic oxides and oxy-hydroxides. Biochar also affected to the distribution of total OC among particle-size fractions. Total OC concentration was greater in fractions 2-20μm, 0.2-2μm, 0.05-0.2μm in biochar-amended plots than in control plots. This may be explained by the adsorption of dissolved OC from fraction <0.05μm onto biochar particles. The results suggested that interactions between biochar, minerals and pre-existing organic matter already occurred in the first year.
authors.affiliation: Department of Mineralogy and Petrology, Science and Technology Faculty, University of the Basque Country (UPV/EHU), Apartado 644, E-48080 Bilbao, Spain; NEIKER-Tecnalia, Department of Conservation of Natural Resources, 812 Bizkaia Science and Technology Park, E-48160 Derio, Spain; European Commission, Joint Research Centre (JRC), Directorate D - Sustainable Resources, Land Resources, Via E. Fermi 2749, I-21027 Ispra (VA), Italy. Electronic address: oihane.fernandez-ugalde@ec.europa.eu.
authors.forename: Oihane
authors.initials: O
authors.lastname: Fernández-Ugalde
authors.affiliation: NEIKER-Tecnalia, Department of Conservation of Natural Resources, 812 Bizkaia Science and Technology Park, E-48160 Derio, Spain.
authors.forename: Nahia
authors.initials: N
authors.lastname: Gartzia-Bengoetxea
authors.affiliation: Department of Mineralogy and Petrology, Science and Technology Faculty, University of the Basque Country (UPV/EHU), Apartado 644, E-48080 Bilbao, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Arostegi
authors.affiliation: NEIKER-Tecnalia, Department of Conservation of Natural Resources, 812 Bizkaia Science and Technology Park, E-48160 Derio, Spain.
authors.forename: Lur
authors.initials: L
authors.lastname: Moragues
authors.affiliation: NEIKER-Tecnalia, Department of Conservation of Natural Resources, 812 Bizkaia Science and Technology Park, E-48160 Derio, Spain.
authors.forename: Ander
authors.initials: A
authors.lastname: Arias-González
keywords: Biochar; Clay minerals; Forest soil; Metallic oxides and oxy-hydroxides; Organic carbon; Particle-size fraction