Contents lists available at ScienceDirect Biomass and Bioenergy journal homepage: www.elsevier.com/locate/biombioe Research paper Can alternative N-fertilization methods infuence GHG emissions and biomass production in sugarcane felds? Clovis D. Borges a , João Luís N. Carvalho a,∗ , Oriel T. Kölln a , Guilherme M. Sanches a , Marcelo J. Silva b , Sergio G.Q. Castro a , Saulo A.Q. Castro c , Luara L. Sousa a , Juliana V.C. Oliveira a , Heitor Cantarella d , Vitor P. Vargas e , Siu M. Tsai f , Henrique C.J. Franco a,g a Brazilian Bioethanol Science and Technology Laboratory (CTBE), National Center for Research in Energy and Materials, Rua Giuseppe Máximo Scolfaro 10000, Polo II de Alta Tecnologia, CEP 13083-970, Campinas, São Paulo, Brazil b Federal University of Paraná, Agricultural Engineering, Rua Dr João Maximiano, 426, Vila Operária, CEP 86900-000, Jandaia do Sul, Paraná, Brazil c University of São Paulo/ESALQ, Dept. of Soil Science, C.P. 09, 13418-900, Piracicaba, SP, Brazil d Agronomic Institute of Campinas, Soil and Environmental Resources Center, C.P. 28, 13020-902, Campinas, SP, Brazil e SLC Agricola, 90620-010, Porto Alegre, RS, Brazil f Center of Nuclear Energy in Agriculture, University of São Paulo, Av. Centenário, 303, Piracicaba, SP, 13400-970, Brazil g Cropman inovação agrícola, Av. José Rocha Bonfim 214, CEP 13080-650, Campinas, SP, Brazil ARTICLEINFO Keywords: Nitrous oxide emissions Saccharum spp. Nitrogen cycle Sugarcane straw Bioethanol ABSTRACT This study evaluated the efect of diferent N fertilizer application methods on N 2 O and CH 4 emissions and on sugarcane biomass yields over two successive growing seasons. Treatments included three methods of N fertilizer (120kgha −1 N) application: 1) above the straw layer; 2) below the straw layer; 3) incorporated into the soil (at 0.1-m soil depth) below the straw layer; and 4) no N application (control). Sugarcane yield for the above straw treatment was, on average, 12% and 15% lower than below the straw and incorporated into the soil, respec- tively. Emissions of CH 4 were very low and unafected by N fertilizer placement. The method and timing of N application infuenced N 2 O emissions. For both years, higher N 2 O emissions were observed from the above straw, followed by below straw and incorporated treatments. Except for the above straw treatment during the wet season, the N 2 O emission factors ranged from 0.08 to 0.62 and were lower than the IPCC default value (1%). The intensity of N 2 O emissions was, on average, 7.45, 3.97 and 3.3 kg CO 2 eq Mg stalk −1 for N applied above straw, below straw and incorporated into the soil, respectively. Changes in the N fertilizer placement method and on the timing of application can signifcantly reduce GHG emissions during sugarcane production, making a signifcant contribution toward a cleaner production of sugarcane ethanol. 1. Introduction It is estimated that the area currently used for sugarcane cultivation in Brazil will expand rapidly, given that the Brazilian government has recently launched the “RenovaBio”, a program designed to boost the share of renewable fuels in the energy mix increasing the ethanol production from 28 billion liters per year in 2015 to around 50 billion litersby2030[1].Alongwiththeincreaseinacreage,anincreaseinthe use of N fertilizer is also expected [2], which may have implications on ecosystems that support agriculture, including NO 3 − leaching, eu- trophication of water bodies [3] and increased nitrous oxide (N 2 O) emissions [4]. Emissions of N 2 O caused by human activities contribute 6% of all terrestrial emissions [5], account for over 80% of emissions from agriculture [6] and have a global warming potential 298 times greater than carbon dioxide. In sugarcane felds, N fertilization is the main source of N 2 O emissions [3] that can further be exacerbated by appli- cation of vinasse (liquid waste from ethanol production) as well as by straw deposition on soil surface [7,8]. Nitrogen fertilizers are re- sponsible for 42% of all greenhouse gas emissions (GHG) generated during sugarcane production [9]. Several studies have evaluated the impacts of N fertilization on GHG emissions, mainly by assessing the impact of dosages [7,10], sources of N fertilizers [10] and organic amendments [7,8,11,12]. Currently in Brazil, most of sugarcane is harvested with no previous burning, preserving a layer of sugarcane straw on the soil surface [13]. https://doi.org/10.1016/j.biombioe.2018.10.017 Received 18 February 2018; Received in revised form 7 October 2018; Accepted 29 October 2018 ∗ Corresponding author. E-mail address: joao.carvalho@ctbe.cnpem.br (J.L.N. Carvalho). Biomass and Bioenergy 120 (2019) 21–27 0961-9534/ © 2018 Elsevier Ltd. All rights reserved. T