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 The simultaneous occurrence of high levels of exchangeable sodium percentage (ESP) and alkalinity in soils imposes restrictions on plant development and affects physical properties such as porosity, bulk density, permeability, and hydraulic conductivity. Although sodic soils are frequent in the flood plain of the São Lourenço River, northern Pantanal, Brazil, few studies focus on their formation and classification, especially with regard to specific processes and detailed classification into lower categorical levels by the different systems available. The aim of this study was to identify the predominant pedogenetic processes occurring in sodic soils of the flood plain of the São Lourenço River to understand their genesis and assess how taxonomic classification systems contemplate the variations in soil properties. Five profiles were selected in sites with different progressive stages of dissection from erosion (P1, P2, P3, P4, and P5). At each site, a pit was dug for morphological description of the profiles and for collecting samples for chemical, particle size, mineralogical, micromorphological, and chronological analyses. Each profile was classified according to the Soil Taxonomy, World Reference Base (WRB), and Brazilian Soil Classification System (SiBCS/Sistema Brasileiro de Classificação de Solos). Argilluviation is the predominant process, with a localized and intense ferrolysis action in the E/Bt transition zones in profile P5. Soils showed signs of lithologic discontinuity. This makes it difficult to distinguish how much of the textural gradient is inherited from fluvial sedimentation processes and how much is the result of pedogenetic processes. In the most advanced stage of alteration, P5 had a paler color, thickening of the E horizon, and an abrupt and irregular transition entering the Bt horizon in the form of a “tongue”. When passing from the most preserved to the most eroded area, ferrolysis becomes more intense in the E/Bt transition, the electrical conductivity values decrease, and the ESP values increase, suggesting the sodification process. Under Soil Taxonomy criteria, P5 was classified as Natraqualf and the other profiles were classified as Natrudalf; under the WRB, however, all profiles were classified as Solonetz. The SiBCS exhibited variation at the Order level, with P5 classified as Planossolo and the others as Luvissolo. Despite an indication of different processes at the Order level, the SiBCS does not yet contemplate the sodic character in the studied Luvissolos. We propose inclusion of the sodic character at the Great Group level, as has already occurred with other SiBCS classes.

Resumo O presente artigo analisa a emergência da questão social da violência sexual infanto-juvenil como problema público, sua inclusão e permanência na agenda formal das políticas nacionais nas décadas de 1990 e 2000. À luz de estudos sobre construção de agendas de políticas públicas e a partir da análise documental, o artigo contextualiza o amplo movimento de articulação e mobilização social da década de 1990, o Plano Nacional de Enfrentamento da Violência Sexual Infanto-juvenil como política pública intersetorial e a década de 2000 pautada pela sua implementação.

Abstract This article analyzes the emergence of the issue of child sexual abuse as a public problem, its inclusion and permanence in the national policy agenda in the decades of 1990 and 2000. Through the construction of public policy agendas and further analysis, this text highlights historical aspects which developed into a huge popular movement in the 1990s against child sexual violence, giving birth to the National Child Sexual Violence Combat Plan as an intersector public policy and the decade of 2000 devoted to its implementation.

Resumo O presente artigo analisa a emergência da questão social da violência sexual infanto-juvenil como problema público, sua inclusão e permanência na agenda formal das políticas nacionais nas décadas de 1990 e 2000. À luz de estudos sobre construção de agendas de políticas públicas e a partir da análise documental, o artigo contextualiza o amplo movimento de articulação e mobilização social da década de 1990, o Plano Nacional de Enfrentamento da Violência Sexual Infanto-juvenil como política pública intersetorial e a década de 2000 pautada pela sua implementação.

Abstract This article analyzes the emergence of the issue of child sexual abuse as a public problem, its inclusion and permanence in the national policy agenda in the decades of 1990 and 2000. Through the construction of public policy agendas and further analysis, this text highlights historical aspects which developed into a huge popular movement in the 1990s against child sexual violence, giving birth to the National Child Sexual Violence Combat Plan as an intersector public policy and the decade of 2000 devoted to its implementation.

ABSTRACT When the harvesting of sugarcane involves a mechanized process, plant residues remain on the soil surface, which makes proximal and remote sensing difficult to monitor. This study aimed to evaluate, under laboratory conditions, differences in the soil spectral behavior of surface layers Quartzipsamment and Hapludox soil classes due to increasing levels of sugarcane’s dry (DL) and green (GL) leaf cover on the soil. Soil cover was quantified by supervised classification of the digital images (photography) taken of the treatments. The spectral reflectance of the samples was obtained using the FieldSpec Pro (350 to 2500 nm). TM-Landsat bands were simulated and the Normalized Difference Vegetation Index (NDVI) and soil line were also determined. Soil cover ranged from 0 to 89 % for DL and 0 to 80 % for GL. Dry leaf covering affected the features of the following soil constituents: iron oxides (480, 530 and 900 nm) and kaolinite (2200 nm). Water absorption (1400 and 1900 nm) and chlorophyll (670 nm) were determinant in differentiating between bare soil and GL covering. Bands 3 and 4 and NDVI showed pronounced variations as regards differences in soil cover percentage for both DL and GL. The soil line allowed for discrimination of the bare soil from the covered soil (DL and GL). High resolution sensors from about 50 % of the DL or GL covering are expected to reveal differences in soil spectral behavior. Above this coverage percentage, soil assessment by remote sensing is impaired.

O Pantanal caracteriza-se por ser uma planície inundável quaternária, com sedimentação predominantemente na forma de leques aluviais. Na evolução geomorfológica e sedimentar, é inerente a esse sistema deposicional o processo de avulsão, cuja dinâmica, associada aos fluxos de águas superficiais de cheias, impõe diferenças sedimentares importantes nessa planície. O entendimento e a diferenciação desses dois eventos podem ajudar na compreensão da variabilidade dos atributos e da distribuição dos solos associados a esses processos sedimentares. Nesse sentido, o objetivo deste trabalho foi estudar a gênese de solos do Pantanal Norte que apresentam contrastes texturais em profundidade e sua relação com a dinâmica do sistema deposicional. Quatro perfis foram estudados na região de Barão de Melgaço, MT (RPPN SESC Pantanal), dois próximos ao rio Cuiabá (AP1 e AP4) e dois próximos ao rio São Lourenço (AP10 e AP11). No AP11, os horizontes apresentam contrastes granulométricos desde a base do perfil até a superfície. No AP1, AP4 e AP10, os horizontes sobrejacentes a uma camada arenosa possuem granulometria semelhante entre si, principalmente na distribuição de areia. No primeiro caso, os fluxos de cheias, ou seja, de águas superficiais, parecem ter originado os horizontes e as camadas contrastantes na textura; no segundo, a avulsão é o processo mais evidente. Dessa forma, as duas vias podem formar solos com contrastes texturais e é possível distingui-los no campo pela morfologia, pois possuem peculiaridades que estão associadas aos processos sedimentares responsáveis pelos depósitos.

The Pantanal region can be characterized as a quaternary floodplain with predominant sedimentation in the form of alluvial fans. In the geomorphologic and sedimentary evolution, the avulsion process is inherent to this depositional system and its dynamics, together with surface water floods, influence soil sedimentation on this plain. The knowledge and differentiation of these two events can contribute to a better understanding of the variability of soil properties and distribution under the influence of these sedimentation processes. Therefore, this study investigated the genesis of soils in the Northern Pantanal with textural contrasts in deeper horizons and their relationship with the depositional system dynamics. We analyzed four soil profiles in the region of Barão de Melgaço, Mato Grosso State, Brazil (RPPN SESC Pantanal). Two profiles were sampled near the Rio Cuiabá (AP1 and AP4) and two near the Rio São Lourenço (AP10 and AP11). In AP11, the horizons contrast in particle size between the profile basis and the surface. In AP1, AP4 and AP10, the horizons overlaying the sand layer have similar particle size properties, mainly in terms of sand distribution. In the first case, floods (surface water) seem to have originated the horizons and layers with contrasting texture. In the second case, avulsion is the most pronounced process. Therefore, the two modes can form soils with contrasting texture that are discriminable by soil morphology, based on the distinct features associated to the specific sedimentation processes.

Insight of nutrient release patterns associated with the decomposition of plant residues is important for their effective use as a green manure in food production systems. Thus, this study aimed to evaluate the ability of the Century, APSIM and NDICEA simulation models for predicting the decomposition and N mineralization of crop residues in the tropical Atlantic forest biome, Brazil. The simulation models were calibrated based on actual decomposition and N mineralization rates of three types of crop residues with different chemical and biochemical composition. The models were also validated for different pedo-climatic conditions and crop residues conditions. In general, the accuracy of decomposition and N mineralization improved after calibration. Overall RMSE values for the decomposition and N mineralization of the crop materials varied from 7.4 to 64.6% before models calibration compared to 3.7 to 16.3 % after calibration. Therefore, adequate calibration of the models is indispensable for use them under humid tropical conditions. The NDICEA model generally outperformed the other models. However, the decomposition and N mineralization was not very accurate during the first 30 days of incubation, especially for easily decomposable crop residues. An additional model variable may be required to capture initial microbiological growth as affected by the moisture dynamics of the residues, as is the case in surface residues decomposition models.

Este trabalho teve como objetivo calibrar os modelos de simulação CENTURY, APSIM e NDICEA para estimar a taxa de decomposição e liberação do N de materiais orgânicos de origem vegetal (amendoim forrageiro, calopogônio, estilosantes e mucuna) durante 360 dias em ambiente tropical do bioma Mata Atlântica. Em sua calibração original, os modelos superestimaram a decomposição e liberação de N dos resíduos dos materiais vegetais, evidenciando a necessidade de calibração para as condições tropicais. O APSIM simulou a decomposição para mucuna e calopogônio, por exemplo, com desvios de 37,62 e 48,23 %, respectivamente, em relação aos dados observados, constituindo-se naquele com menor grau de acurácia dos modelos sem calibração. Sem a calibração, o NDICEA apresentou desvios de 10,46 e 14,46 %, e o CENTURY, de 21,42 e 31,84 %, para a decomposição dos resíduos de mucuna e calopogônio, respectivamente. Depois de calibrados, os modelos apresentaram alto grau de acurácia tanto para decomposição quanto para liberação de N, com desvios abaixo de 20 % em relação aos dados observados. O NDICEA calibrado foi o modelo com maior grau de acurácia, seguido do APSIM e CENTURY. Os modelos apresentaram baixo rendimento para os primeiros meses de decomposição e liberação de N, indicando a necessidade da incorporação neles de uma variável que represente o crescimento microbiológico inicial sobre os resíduos e o papel da lavagem inicial do material com água de chuva.

The aim of this study was to calibrate the CENTURY, APSIM and NDICEA simulation models for estimating decomposition and N mineralization rates of plant organic materials (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum, Stylosanthes guyanensis) for 360 days in the Atlantic rainforest bioma of Brazil. The models´ default settings overestimated the decomposition and N-mineralization of plant residues, underlining the fact that the models must be calibrated for use under tropical conditions. For example, the APSIM model simulated the decomposition of the Stizolobium aterrimum and Calopogonium mucunoides residues with an error rate of 37.62 and 48.23 %, respectively, by comparison with the observed data, and was the least accurate model in the absence of calibration. At the default settings, the NDICEA model produced an error rate of 10.46 and 14.46 % and the CENTURY model, 21.42 and 31.84 %, respectively, for Stizolobium aterrimum and Calopogonium mucunoides residue decomposition. After calibration, the models showed a high level of accuracy in estimating decomposition and N- mineralization, with an error rate of less than 20 %. The calibrated NDICEA model showed the highest level of accuracy, followed by the APSIM and CENTURY. All models performed poorly in the first few months of decomposition and N-mineralization, indicating the need of an additional parameter for initial microorganism growth on the residues that would take the effect of leaching due to rainfall into account.