title: Biochar amendment to soil changes dissolved organic matter content and composition.
abstract: Amendments of biochar, a product of pyrolysis of biomass, have been shown to increase fertility of acidic soils by enhancing soil properties such as pH, cation-exchange-capacity and water-holding-capacity. These parameters are important in the context of natural organic matter contained in soils, of which dissolved organic matter (DOM) is the mobile and most bioavailable fraction. The effect of biochar on the content and composition of DOM in soils has received little research attention. This study focuses on the effects of amendments of two different biochars to an acidic acrisol and a pH-neutral brown soil. A batch experiment showed that mixing biochar with the acrisols at a 10 wt.% dose increased the pH from 4.9 to 8.7, and this resulted in a 15-fold increase in the dissolved organic carbon concentration (from 4.5 to 69 mg L(-1)). The pH-increase followed the same trend as the release of DOM in the experiment, causing higher DOM solubility and desorption of DOM from mineral sites. The binding to biochar of several well-characterised reference DOM materials was also investigated and results showed a higher sorption of aliphatic DOM to biochar than aromatic DOM, with DOM-water partitioning coefficients (Kd-values) ranging from 0.2 to 590 L kg(-1). A size exclusion occurring in biochar's micropores, could result in a higher sorption of smaller aliphatic DOM molecules than larger aromatic ones. These findings indicate that biochar could increase the leaching of DOM from soil, as well as change the DOM composition towards molecules with a larger size and higher aromaticity.
authors.affiliation: Norwegian Geotechnical Institute (NGI), P.O. Box 3930, Ullevål Stadion, NO-0806 Oslo, Norway; Department of Chemistry, University of Oslo (UiO), P.O. Box 1033, Blindern, NO-0315 Oslo, Norway. Electronic address: and@ngi.no.
authors.forename: Andreas
authors.initials: A
authors.lastname: Smebye
authors.affiliation: Norwegian Geotechnical Institute (NGI), P.O. Box 3930, Ullevål Stadion, NO-0806 Oslo, Norway.
authors.forename: Vanja
authors.initials: V
authors.lastname: Alling
authors.affiliation: Department of Chemistry, University of Oslo (UiO), P.O. Box 1033, Blindern, NO-0315 Oslo, Norway.
authors.forename: Rolf D
authors.initials: RD
authors.lastname: Vogt
authors.affiliation: Department of Chemistry, University of Oslo (UiO), P.O. Box 1033, Blindern, NO-0315 Oslo, Norway.
authors.forename: Tone C
authors.initials: TC
authors.lastname: Gadmar
authors.affiliation: Department of Environmental Sciences (IMV), Norwegian University of Life Sciences (NMBU), P.O. Box 5003, NO-1432 Ås, Norway.
authors.forename: Jan
authors.initials: J
authors.lastname: Mulder
authors.affiliation: Norwegian Geotechnical Institute (NGI), P.O. Box 3930, Ullevål Stadion, NO-0806 Oslo, Norway; Department of Environmental Sciences (IMV), Norwegian University of Life Sciences (NMBU), P.O. Box 5003, NO-1432 Ås, Norway; Department of Applied Environmental Sciences (ITM), Stockholm University, 10691 Stockholm, Sweden.
authors.forename: Gerard
authors.initials: G
authors.lastname: Cornelissen
authors.affiliation: Norwegian Geotechnical Institute (NGI), P.O. Box 3930, Ullevål Stadion, NO-0806 Oslo, Norway.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Hale
mesh_terms: D000327:Adsorption; D002606:Charcoal / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009930:Organic Chemicals / Q000032:analysis* / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012995:Solubility
chemical_list: D009930:Organic Chemicals; D012987:Soil; C540010:biochar; D002606:Charcoal
keywords: Acrisol; Biochar; Dissolved organic matter; Soil amendment; Sorption