Resumo O objetivo deste trabalho foi avaliar o potencial de mitigação de óxido nitroso (N2O) 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 N2O. O sistema de ILPF apresenta potencial promissor para mitigar as emissões de N2O, 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.

Abstract 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 N2O emissions. The ICLF system has promising potential to mitigate N2O 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.

AbstractThis study evaluates the chemical processes responsible for the nitrous oxide (N2O) and methane (CH4) fluxes in the managed pasture (PM) and unmanaged pasture (PNM). In addition, the impact of nitrogen fertilization on the N2O and CH4 fluxes was assessed. The experiments were conducted on three farms in Alta Floresta city in the state of Mato Grosso. Both regular and intensive samples were collected from PM, PNM, and forest areas for each of the properties. The gases were sampled using static chambers in the morning. Higher N2O fluxes were recorded in the PMs, whereas the CH4 fluxes showed no influence of nitrogen fertilization in both regular and intensive samples. Low fertilizer levels resulted in low N2O emissions.