Carbon stability and mitigation of fertilizer induced N 2 O emissions in soil amended with biochar Priscila Grutzmacher a, ⁎, Aline Peregrina Puga a , Maria Paula Silveira Bibar b , Aline Renée Coscione c , Ana Paula Packer a , Cristiano Alberto de Andrade a a Embrapa Meio Ambiente, Rodovia SP 340, km 127,5, 13820-000 Jaguariúna, SP, Brazil b JBS Ambiental, Rodovia BR 040, km 22,5, 72814-970 Luziânia, GO, Brazil c Instituto Agronômico de Campinas, Laboratório de Qualidade do Solo, Avenida Barão de Itapura, 1481, 13012-970 Campinas, SP, Brazil HIGHLIGHTS • The stability of C from biochars is 3 to 4 times higher than feedstock. • Sewage sludge biochar reduced 87% of nitrogen fertilizer N 2 O emissions. • Application of sewage sludge biochar presented 0.01% of N 2 O emission factor. GRAPHICAL ABSTRACT abstract article info Article history: Received 21 September 2017 Received in revised form 4 December 2017 Accepted 18 December 2017 Available online xxxx Editor: Ajit Sarmah Biochar is a promising tool for an efficient and low environmental impact agriculture since can offer both soil car- bon (C) sequestration and mitigation of nitrous oxide (N 2 O) emissions. The extent of biochar C stability after soil amendment and efficiency in reducing N 2 O emissions from an external nitrogen (N) source were accessed through laboratory incubations. A clay loam soil was amended with chicken manure (CM), sewage sludge (SS), eucalyptus sawdust (ES) and filter cake (FC) feedstocks and corresponding slow-pyrolysis (400 °C) biochars at 5 g C kg −1 soil in combination with two N fertilizer rates (0 and 140 mg N kg −1 soil). Carbon dioxide (CO 2 ) and N 2 O emissions were measured during 60 days. Biochars and feedstocks CO 2 emissions were described by an ex- ponential first order kinetics model. For C mineralization an interaction effect was observed for feedstock source and organic amendment. Lower values of mineralizable C was found for biochars than corresponding feedstocks, except for ES. Carbon losses in 60 days of incubation totaled between 0.8 and 9.4% and 2.4 and 32% for biochars and feedstocks, respectively. Regarding to N 2 O emissions, only CM-biochar impacted emissions with a two-fold increase in non-fertilized soil. When NH 4 NO 3 was co-applied, biochars reduced fertilizer induced N 2 O emissions, reaching a seven-fold reduction in SS-biochar treatment. The fertilizer emission factor (EF) decreased with bio- char amendments as well, varying between 0.01 and 0.08% of the fertilizer N emitted as N 2 O, which shows the biochar potential to reduce fertilizer induced N 2 O emissions, with major reduction by SS-biochar mitigating 87% of the soil-fertilizer emissions. Such potential could be explored by designing biochars based on feedstock chemical and structural properties, including a mixed feedstock source biochar that promotes C sequestration and mitigates N 2 O emissions. © 2017 Elsevier B.V. All rights reserved. Keywords: Pyrolized biomass Greenhouse gas emissions Nitrogen Carbon sequestration Black carbon Science of the Total Environment 625 (2018) 1459–1466 ⁎ Corresponding author. E-mail addresses: priscila.grutzmacher@gmail.com (P. Grutzmacher), aline@iac.sp.gov.br (A.R. Coscione), paula.packer@embrapa.br (A.P. Packer), cristiano.andrade@embrapa.br (C.A. de Andrade). https://doi.org/10.1016/j.scitotenv.2017.12.196 0048-9697/© 2017 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv