title: Impact of biochar on nitrous oxide emissions from upland rice.
abstract: The objective of this research was to assess the emission of nitrous oxide (N2O) from soil amended with biochar in the culture of upland rice. The experiment was conducted in the field in a Cerrado Haplic Plinthosol under randomized block experimental design. The treatments consisted of fertilization with 100 kg N ha(-1) split into two applications, 60% at sowing and 40% at 45 days after crop emergence, combined with four doses of biochar (0, 8, 16 and 32 Mg ha(-1)), with four replications. The application of N and the emission of N2O, moisture retention and soil temperature, respiration (C-CO2), microbial biomass carbon in the soil (C-SMB), total nitrogen (TN), pH and agronomic efficiency in N use (AENu) were evaluated five years after the application of biochar. There was a significant correlation of the application of biochar with moisture retention (r = 0.94**), N2O emission (r = 0.86**) and soil pH (r = 0.65*), and N2O emissions showed a positive correlation (p < 0.05) with soil moisture (r = 0.77**) and pH (r = 0.66*). Thus the highest N2O emissions were observed shortly after N fertilization and in the treatments with 32 Mg ha(-1) of biochar. Despite the higher N2O emissions from the application of 32 Mg ha(-1) of biochar, the emission factor was lower (0.81%) than the maximum recommended by the IPCC. The higher N2O emissions with application of biochar are offset by more efficient use of N and consequently the possibility of reduction of applied doses.
authors.affiliation: Universidade Federal de Mato Grosso (UFMT), Instituto de Ciências Agrárias e Ambientais, CEP: 78557-267, Sinop, MT, Brazil. Electronic address: petter@ufmt.br.
authors.forename: Fabiano André
authors.initials: FA
authors.lastname: Petter
authors.affiliation: Universidade Federal de Mato Grosso (UFMT), Instituto de Ciências Agrárias e Ambientais, CEP: 78557-267, Sinop, MT, Brazil.
authors.forename: Larissa Borges
authors.initials: LB
authors.lastname: de Lima
authors.affiliation: Universidade do Estado de Mato Grosso (UNEMAT), Campus de Nova Xavantina, PO Box 08, CEP 78690-000, Nova Xavantina, MT, Brazil.
authors.forename: Ben Hur
authors.initials: BH
authors.lastname: Marimon Júnior
authors.affiliation: Universidade Federal de Mato Grosso (UFMT), Instituto de Ciências Agrárias e Ambientais, CEP: 78557-267, Sinop, MT, Brazil.
authors.forename: Leidimar
authors.initials: L
authors.lastname: Alves de Morais
authors.affiliation: Universidade do Estado de Mato Grosso (UNEMAT), Campus de Nova Xavantina, PO Box 08, CEP 78690-000, Nova Xavantina, MT, Brazil.
authors.forename: Beatriz Schwantes
authors.initials: BS
authors.lastname: Marimon
mesh_terms: D018533:Biomass; D002244:Carbon / Q000032:analysis; D002606:Charcoal; D058440:Denitrification; D058465:Nitrification; D009584:Nitrogen / Q000378:metabolism; D009609:Nitrous Oxide / Q000032:analysis*; D012275:Oryza / Q000378:metabolism; D012987:Soil / Q000737:chemistry*
chemical_list: D012987:Soil; C540010:biochar; D002606:Charcoal; D002244:Carbon; D009609:Nitrous Oxide; D009584:Nitrogen
keywords: Denitrification; Efficient use of nitrogen; Nitrification; Oryza sativa; Pyrogenic carbon