ABSTRACT Although agriculture and livestock systems represent important sources of N2O from the soil, they may also aid in emissions mitigation, mainly when integrated systems are taken into account, such as crop-livestock-forest, for food production. This work assessed the soil N2O emissions from a tropical Oxisol under row-crop, livestock, forest monocultures, and an integrated crop-livestock-forest system in the Southern Amazon - Brazil. Soil N2O emissions were measured using static chambers from November 2014 to October 2016 in four soil use systems [row-crop, livestock, forest, and integrated crop-livestock-forest (CLF)], and in a reference area under native forest fragment. For the whole period, the average of soil N2O fluxes was 16.9, 12.2, and 15.4 µg N2O-N m-2 h-1, to row-crop, livestock, and CLF systems, respectively, all with a similar average among them. The lowest fluxes were observed in the forest system and native forest fragment, with average fluxes of 4.0 and 6.3 µg N2O-N m-2 h-1, respectively, both lower than the agricultural systems. The largest soil N2O fluxes were observed throughout the rainy seasons in the row-crop, livestock, and CLF, mostly after N-fertilizer application to the soil surface or in the planted row. As a consequence, the cumulative emissions were greater in row-crop, livestock, and CLF systems, which in the averages of two cycles emitted respectively 1.40, 1.15, and 1.27 kg N2O-N ha-1 yr-1, all different of the forest system and native forest fragment (0.33 and 0.52 kg N2O-N ha-1 yr-1, respectively). Nitrogen fertilization and soil moisture influenced soil N2O emissions of all systems assessed in the Southern Amazon. The N2O emissions took place after both factors were met, corroborating the hole-in-the-pipe model. Even with more soil use intensification, once in the same area there were three cultures in succession during a year and perennial trees, CLF did not lead to greater N2O emissions from the soil than row-crop and livestock. Thus, CLF represents a good option for N2O mitigation for the edaphic and climatic conditions of the Southern Amazon.

Resumo: O objetivo deste trabalho foi avaliar a influência da frequência de amostragem de gases na estimativa das emissões acumuladas de óxido nitroso (N2O) do solo. Foram avaliadas emissões de gases durante dois anos (2014-2016), em quatro sistemas: plantio de eucalipto, lavoura, pastagem e fragmento florestal. As estimativas acumuladas de N2O foram calculadas para intervalos de 7, 14 e 21 dias. Os intervalos de amostragem não influenciaram os resultados finais de emissões acumuladas de N2O do solo nos sistemas avaliados.

Abstract: The objective of this work was to assess the influence of gas sampling frequency on the cumulative emissions of nitrous oxide (N2O) from the soil. Gas emissions were assessed over a period of two years (2014-2016), in four systems: eucalyptus forestry, crops, pasture, and native forest. The cumulative emissions of N2O were calculated at sampling intervals of 7, 14, and 21 days. The sampling intervals did not influence the final results of cumulative N2O emissions from the soil in the assessed systems.

ABSTRACT This study aimed to evaluate the frequency and intensity of GreenFeed (GF) use by Nellore steers using different attractants in pastures of integrated systems. The attractant protein supplement and Tifton bermudagrass pelleted hay flavored with vanilla were evaluated over a period of 15 days. The pelleted hay stimulated the animals to stay longer in the equipment (24.23 s), with 8% more visits in intervals longer than 30 s in contrast to protein supplement. This indicates that pelleted hay flavored with vanilla is a potential attractant to encourage Nellore steers to visit GF in grazing systems.

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.

RESUMOVários artigos vêm mostrando que os sistemas de metrô causam impactos na qualidade do ar, através da emissão de material particulado. No entanto, não há informações disponíveis sobre o efeito desse impacto na vegetação. Folhas de árvores de três espécies diferentes localizadas do lado da saída de dutos de um metrô no Rio de Janeiro, Brasil, se mostraram mais assimétricas do que as de árvores localizadas do lado da entrada. Essas folhas também apresentaram alterações na camada de cera epicuticular e no conteúdo de clorofila.

ABSTRACTWhile a number of papers have shown that subway systems have an impact on the air quality through the release of particulate matters, no information about the impact of such particles on tree attributes is available. Tree leaves from three different species from the exit side of a subway station in Rio de Janeiro, Brazil, were more asymmetrical than leaves from the entrance side. This leaves also presenting changes in leaves cuticle and chlorophyll content.

Soil fluxes of N2O were determined over one year in montane tropical rainforest of southeastern Brazil with average annual rainfall of 2.8 m. Annual mean (± standard deviation) and median N2O fluxes were 3.0 ± 1.4 and 2.7 µg N m-2 h-1, respectively, is 5-10 times lower than mean values reported in literature for tropical rainforest soils in the Amazon basin. N2O fluxes varied spatially and seasonally, were about twice as high during summer as in winter, and significantly influenced by both monthly precipitation and soil temperature.

Wet and dry (dust) deposition was measured in the Serra dos Órgãos National Park. VWM pH was 5.3. Non-sea-salt (nss) SO4(2-) comprised 97% of total SO4(2-). The molar ratio [2(nss-SO4(2-)) + NO3-]/[NH4+ + H+] was 1.1, suggesting that pH is predominantly controlled by H2SO4, HNO3, and NH3. Wet deposition of NH4+, NO3-, and nss-SO4(2-) was respectively 0.59, 0.25, and 0.30 kmol ha-1 yr-1. Assuming that dry deposition of N can comprise 30-50% of its total (dry + wet) deposition, the latter is estimated to be 1.2-1.7 kmol ha-1 yr-1 (17-24 kg N ha-1 yr-1).