Resumo -O objetivo deste trabalho foi avaliar o potencial de mitigação de óxido nitroso (N 2 O) em sistema de integração lavoura-pecuária-floresta (ILPF), em comparação ao monocultivo, e identificar os principais fatores que regulam as emissões deste gás. O experimento foi realizado em Sinop, MT, entre as safras 2012/2013 e 2013/2014, e avaliou os seguintes tratamentos: floresta, lavoura e pastagem, além do ILPF. Durante a realização do experimento, não houve presença de bovinos nas áreas com pastagem. Amostras de óxido nitroso foram coletadas semanalmente, com uso de câmaras estáticas, modelo topo-base. As concentrações do gás foram determinadas por meio de cromatografia gasosa. A precipitação pluvial e a disponibilidade de N foram os principais fatores reguladores das emissões de N 2 O. O sistema de ILPF apresenta potencial promissor para mitigar as emissões de N 2 O, com emissão acumulada de 0,367 kg ha -1 de N, em comparação a de 1,401 kg ha -1 emitidas pela lavoura; de 0,298 kg ha -1 , pela pastagem; e de 0,165 kg ha -1 , pela floresta.Termos para indexação: gases de efeito estufa, mudança do clima, sistemas integrados de produção. Nitrous oxide fluxes in an integrated crop-livestock-forestry systemAbstract -The objective of this work was to evaluate the mitigation potential of nitrous oxide in an integrated crop-livestock-forestry system (ICLF), compared with monocultures, and to identify the main factors that regulate the emissions of this gas. The experiment was conducted in the municipality of Sinop, in the state of Mato Grosso, Brazil, between the 2012/2013 and 2013/2014 crop seasons, with the evaluation of the following treatments: forest, crop and pasture, besides ICLF. During the experiment, no cattle were present in the pasture areas. Nitrous oxide samples were collected weekly using top-down static chambers. Gas concentrations were determined with gas chromatography. Rainfall and N availability were main factors regulating N 2 O emissions. The ICLF system has promising potential to mitigate N 2 O emissions, with 0.367 kg ha -1 N accumulated emission, compared with 1.401 kg ha -1 from cropland, 0.298 kg ha -1 from pasture, and 0.165 kg ha -1 from forest.

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The Brazilian agricultural sector is largely responsible for nitrous oxide (N2O) soil emissions, mainly due to beef cattle and the use of synthetic nitrogen fertilizers. Therefore, Brazil is looking for measures, such as integrated crop–livestock– forest (ICLF), to increase productivity and reduce greenhouse gas emissions in this sector. The forest component within this system plays a positive role in the context of climate change, soil conservation, carbon dioxide (CO2) sequestration, and biodiversity protection. The aim of this study was to evaluate the effect of management and rainfall on N2O emissions in eucalypt monoculture soils and eucalypt soils in ICLF systems. Manual static chambers were used to collect gas samples, from November 2013 to October 2014, in four treatments, i.e., one eucalypt monoculture (F) and three modalities of ICLF (livestock–forest [LF], livestock–crop–forest [LCF], and integrated crop–livestock–forest [ICLF]). A gas chromatograph with an electron capture detector was used to measure the N2O concentrations. The results showed that rainfall considerably affected N2O fluxes across all the treatments, indicating that rainfall is the main factor in increasing emissions. During the wet season, the N2O levels ranged from 0.158 to 0.482 kg N-N2O ha-1 across all treatments. During the dry season, all treatments behaved like sinks of N2O. Moreover, N2O flux did not differ between the soils in the eucalypt monoculture and ICLF systems. This indicates that the forestry component in the ICLF systems did not affect N2O soil fluxes.