The objective of this study was to evaluate the effect of seasons under a tropical climate on forage quality, aswell the effect of an Urochloa brizantha cv. Marandu grazing system on enteric methane (CH4) emissions fromNellore cattle in the Southeast region of Brazil. Sixteen Nellore steers (18 months old and initial weight 318.0 ± 116.59 kg of LW; final weight 469 ± 98.50 kg of LW) were used for a trial period of 10 months, with four collection periods in winter (August), spring (December), summer (February) and autumn (May). Each collection period consisted of 28 days, corresponding to the representative month of each season where the last six days were designed for methane data collection. Animals were randomly distributed within 16 experimental plots, distributed in four random blocks over four trial periods. CH4 emissions were determined using the sulphur hexafluoride (SF6) tracer gas technique measured by gas chromatography and fluxes of CH4 calculated. The forage quality was characterized by higher CP and IVDMD and lower lignin contents in spring, differing specially from winter forage. Average CH4 emissions were between 102.49 and 220.91 g d-1 (37.4 to 80.6 kg ani-1 yr-1); 16.89 and 30.20 g kg-1 DMI; 1.35 and 2.90 Mcal ani-1 d-1; 0.18 and 0.57 g kg-1 ADG-1 and 5.05 and 8.76% of GE. Emissions in terms of CO2 equivalents were between 4.68 and 14.22 g CO2-eq-1 g-1 ADG. Variations in CH4 emissions were related to seasonal effect on the forage quality and variations in dry matter intake.

We aimed to quantify nitrous oxide (N₂O) and methane (CH₄) emissions as a function of the addition of different quantities of bovine faeces and urine on soil under pasture. Two experiments were performed in randomised complete blocks with five replicates. In the first experiment, the emissions of CH₄ and N₂O were evaluated for 14 days after the addition of four amounts of faeces (0.0, 1.2, 1.8 and 2.4 kg of fresh faeces per plot), and in a second experiment, N₂O emissions were evaluated for 43 days after addition of four volumes of urine (0.0, 1.0, 1.5 and 2.0 L). Urine and faeces came from crossbred (Fresian × Gir) dairy cows fed on pasture and concentrates. N₂O emissions from faeces did not alter the emission factor (EF) according to the faeces weight (P = 0.73). N₂O-N EF from faeces-N averaged 0.18% (±0.05) of total applied N. The volume of urine applied influenced N₂O losses. The EF decreased linearly (P = 0.015) with increasing volumes of urine, being 4.9% (±0.75), 3.36% (±0.7) and 2.43% (±0.46) of N applied emitted as N₂O for the 1.0, 1.5 and 2.0 L volumes of urine respectively. The EF from urine was significantly (P < 0.0001) higher than the EF from faeces. There was no change to the CH₄ emissions per kilogram of excreta when the amount of faeces added was varied (P = 0.87). However, the CH₄ emitted increased linearly with the amount of faeces (P = 0.02). The CH₄ EF was estimated to be 0.95 (±0.38) kg/head.year.

As a contribution to an Integrated Water Resources Management (IWRM) project in Distrito Federal, Brazil, we address several aspects for a credible downscaling of near-surface air temperature and precipitation using the Statistical DownScaling Model (SDSM4.2). For instance, we apply a detailed screening of predictors, consider the end user needs in the validation procedure, assess the added value of the downscaling model and include several sources of uncertainties until the downscaling step. Results suggest that the interpolation of large-scale predictors to the target site is a reasonable alternative to predictors derived from grid-boxes. The validation metrics, measures (i.e. bias, root-mean-square error, and Pearson’s correlation coefficient) and quantile–quantile plots reveal that model tends to underestimate near-surface temperature and precipitation; whereas extreme values are subject of considerable uncertainties. Single-site projections at daily scale are derived from 27 climate models from the Coupled Model Intercomparison Project phase 5 (CMIP5) forced by Representative Concentration Pathways (i.e. RCP2.6, RCP4.5, RCP6.0 and RCP8.5) scenarios. The downscaling model adds substantial value in terms of amplitude of variability when compared to the host coarse-resolution projections. Its performance is higher than a quantile-mapping bias correction technique, particularly in reproducing observed trends. In spite of the elevated level of uncertainties in the magnitude of change, most of the downscaled projections agree on positive changes in near-surface temperature and precipitation for the period of 2036–2055 when compared to the reference period (i.e. 1986–2005). The massive amount of downscaled projections is of limited application in hydrological studies and, therefore, we suggest a summarized group of projections which are representative to the central tendency and spread of the ensemble.

Crop models can aid the synthesis and application of knowledge, planning of experiments and forecasting in agricultural systems. Few studies have reviewed the uses and applications of these models for tropical forages. The purpose of this study was to review the information available in this scientific area, highlighting the main models, their applications and limitations. Several empirical models have been developed to predict the growth and biomass accumulation of tropical forages, especially for the genera Cynodon, Paspalum, Panicum and Brachiaria. Their application, however, is often location or region specific. The adaptation of mechanistic models to accurately predict biomass accumulation in tropical grasses is still limited. Recent advances have been made on the plot-scale and farm-scale process-based models ALMANAC, CROPGRO Perennial Forage and agricultural production systems simulator (APSIM), with promising results. In addition, global-scale process-based models, such as the Century Agroecosystem Model and the Orchidee Grassland Management Model, have been tested for tropical grassland areas. A greater number of region-specific calibrations of empirical models can enhance their use, and improved databases and model parameterizations for a wide range of tropical grasses will enable the continuous improvement of mechanistic models.

Este artigo tem como objetivo inserir a proposta de organização da agricultura baseada nos conceitos da Integração Lavoura-Pecuária-Floresta (ILPF) no âmbito das discussões relacionadas à necessidade de transformação do modelo produtivo vigente. Foram utilizadas as diretrizes e os conceitos relacionados com a Green Economy Initiative (GEI), uma iniciativa do Programa das Nações Unidas para o Meio Ambiente (Pnuma). Busca-se mostrar que a proposta ILPF está alinhada com os aspectos de agricultura sustentável proposta na GEI, e que a ILPF se coloca como uma importante estratégia de aumento da produção agropecuária de forma sustentável para o Brasil. A adoção da GEI é uma estratégia consistente para a implementação de políticas com a finalidade de promover o desenvolvimento sustentável. Dessa forma, a produção agrícola baseada no modelo ILPF alinha-se perfeitamente com as premissas da GEI no que tange à promoção e incentivos a modelos de agricultura de baixo carbono.

This study presents data from field experiments that focus on the influence of coral reef geometry on wave transformation in the Metropolitan Area of Recife (MAR) on the northeast coast of Brazil. First, a detailed bathymetric survey was conducted, revealing a submerged reef bank, measuring 18 km long by 1 km wide, parallel to the coastline with a quasi-horizontal top that varies from 0.5 m to 4 m in depth at low tide. Cluster similarity between 180 reef profiles indicates that in 75% of the area, the reef geometry has a configuration similar to a platform reef, whereas in 25% of the area it resembles a fringing reef. Measurements of wave pressure fluctuations were made at two stations (experiments E1 and E2) across the reef profile. The results indicate that wave height was tidally modulated at both experimental sites. Up to 67% (E1) and 99.9% (E2) of the incident wave height is attenuated by the reef top at low tide. This tidal modulation is most apparent at E2 due to reef geometry. At this location, the reef top is only approximately 0.5 m deep during mean low spring water, and almost all incident waves break on the outer reef edge. At E1, the reef top depth is 4 m, and waves with height ratios smaller than the critical breaking limit are free to pass onto the reef and are primarily attenuated by bottom friction. These results highlight the importance of reef geometry in controlling wave characteristics of the MAR beaches and demonstrate its effect on the morphology of the adjacent coast. Implications of differences in wave attenuation and the level of protection provided by the reefs to the adjacent shoreline are discussed.

Estuaries comprise broad spectra of systems whose morphology often rule theirs hydrodynamics. The Itamaracá estuarine system (NE-Brazil) is formed by the Santa Cruz Channel (SCC), connecting to the Atlantic Ocean through two inlets. Water level and in depth current measurements were used to evaluate an analytical approach for representing its tidal circulation. Depth-averaged currents were analytically predicted with 11% error (δ1 = 0.11). Currents measurements for five different sampling stations and depths were compared to model responses for various values of eddy viscosity (ν) and bottom friction parameter (r). The best-fit quadratic error δ2 = 0.155 was obtained with ν = 6.3×10−3m2s−1 and r = 6.5×10−3ms−1. Model improvements, considering bottom friction and eddy diffusivity formulations, indicated a boundary layer depth of 0.10H (H=channel depth), and a large (6.1×10−3m) mean roughness length of the sea-bed to couple with the intricate roots system of red mangroves along the SCC. Simulations were also used to test Taylor’s (1954) scale analysis, yielding c = 0.080 as best value (c = ν/u*H constant; u* =bottom friction velocity) and a mean eddy viscosity of 5.8×10−3 m2s−1). The low sensibility of momentum distribution to changes in eddy viscosity verified suggests that stronger viscosity dumping may be compensated by higher bottom shear stress. This simple analytical approach could also be used to predict spatial and temporal distribution of pollutants and other materials at SSC and at similar systems as advection of those components could easily be simulated combining modelled currents with measurements of theirs concentrations.

This paper presents a study about wave climate acting on the Northeast coast of Brazil (Recife, Pernambuco) from the use of X-band nautical radar, which runs through the emission of electromagnetic waves and receives the signal by backscattering the sea surface. The main objective of this work is to obtain information about the wave acting on this coast, by analyzing significant height, period and direction of the incident waves, which will be helpful to generate a solid database for future coastal measures, engineering works of contention for coastal and marine protection. Data were obtained from polar images of X-band nautical radar, from April 2010 to April 2011. By analysing the results, it was possible to observe the joint occurrence of waves wind sea and swell in the region of study. Wind sea waves occur predominantly at 90° – 135°, with higher values at the end of September (3.9 m). Swell waves were more frequent during June, October and December 2010, and February and March 2011. Moreover, we observed a change in direction of the waves and decrease in wave heights along the inner shelf of the coast, caused by variation in bathymetry and the presence of sandstone reefs. The results of this study demonstrated great efficiency in acquiring the physical parameters of waves through the X-band nautical radar system, proving to be an efficient tool for measuring physical parameters of waves in coastal regions.

Brazil has the largest herd of beef cattle in the world, estimated at approximately 200 million animals. Production is predominantly pasture-based and low input and hence time to slaughter is long, which promotes high methane (CH4) emissions per kg of product. The objective of this study was to investigate the impact of increasing animal productivity using fertilizers, forage legumes, supplements and concentrates, on the emissions of greenhouse gases (GHGs) in five scenarios for beef production in Brazil. A life cycle analysis (LCA) approach, from birth of calves to mature animals ready for slaughter at the farm gate, was utilized using Tier 2 methodologies of the IPCC and the results expressed in equivalents of carbon dioxide (CO2eq) per kg of carcass produced. Fossil CO2 emitted in the production of supplements, feeds and fertilizers was included using standard LCA techniques. The first four scenarios were based solely on cattle production on pasture, ranging from degraded Brachiaria pastures, through to a mixed legume/Brachiaria pasture and improved N-fertilized pastures of Guinea grass (Panicum maximum). Scenario 5 was the most intensive and was also based on an N-fertilized Guinea grass pasture, but with a 75-day finishing period in confinement with total mixed ration (TMR). Across the scenarios from 1 to 5 the increase in digestibility promoted a reduction in the forage intake per unit of animal weight gain and a concomitant reduction in CH4 emissions. For the estimation of nitrous oxide (N2O) emissions from animal excreta, emission factors from a study in the Cerrado region were utilized which postulated lower emission from dung than from urine and much lower emissions in the long dry season in this region. The greatest impact of intensification of the beef production systems was a 7-fold reduction of the area necessary for production from 320 to 45 m2/kg carcass. Carcass production increased from 43 to 65 Mg per herd across the scenarios from 1 to 5, and total emissions per kg carcass were estimated to be reduced from 58.3 to 29.4 kg CO2eq/kg carcass. Even though animal weight gain was lower in the mixed grass-legume scenario (3) than for the N-fertilized Guinea grass pastures (scenarios 4 and 5) GHG emissions per kg carcass were similar as the legume N2 fixation input had no fossil-fuel cost. A large source of uncertainty for the construction of such LCAs was the lack of data for enteric CH4 emissions from cattle grazing tropical forages.

Brazil has the largest herd of beef cattle in the world, estimated at approximately 200 million animals. Production is predominantly pasture-based and low input and hence time to slaughter is long, which promotes high methane
(CH4) emissions per kg of product. The objective of this study was to investigate the impact of increasing animal productivity using fertilizers, forage legumes, supplements and concentrates, on the emissions of greenhouse gases (GHGs) in five scenarios for beef production in Brazil. A life cycle analysis (LCA) approach, from birth of calves to mature animals ready for slaughter at the farm gate, was utilized using Tier 2 methodologies of the IPCC and the results expressed in equivalents of carbon dioxide (CO2eq) per kg of carcass produced. Fossil CO2 emitted in the production of supplements, feeds and fertilizers was included using standard LCA techniques. The first four scenarios were based solely on cattle production on pasture, ranging from degraded Brachiaria pastures, through to a mixed legume/Brachiaria pasture and improved N-fertilized pastures of Guinea grass (Panicum maximum). Scenario 5 was the most intensive and was also based on an N-fertilized Guinea grass pasture, but with a 75-day finishing period in confinement with total mixed ration (TMR). Across the scenarios from 1 to 5 the increase in digestibility promoted a reduction in the forage intake per unit of animal weight gain and a concomitant reduction in CH4 emissions. For the estimation of nitrous oxide (N2O) emissions from animal excreta, emission factors from a study in the Cerrado region were utilized which postulated lower emission from dung than from urine and much lower emissions in the long dry season in this region. The greatest impact of intensification of the beef production systems was a 7-fold reduction of the area necessary for production from 320 to 45 m2 /kg carcass. Carcass production increased from 43 to 65 Mg per herd across the scenarios from 1 to 5, and total emissions per kg carcass were estimated to be reduced from 58.3 to 29.4 kg CO2eq/kg carcass. Even though animal weight gain was lower in the mixed grass-legume scenario (3) than for the N-fertilized Guinea grass pastures (scenarios 4 and 5) GHG emissions per kg carcass were similar as the legume N2 fixation input had no fossil-fuel cost. A large source of uncertainty for the construction of such LCAs was the lack of data for enteric CH4 emissions from cattle grazing tropical forages.

Fisheries become undermined as floodplains suffer increasing pressure from infrastructure, pollution, changes in climate and over-extraction. For Amazonian riverside communities, less fish in the rivers and lakes means empty pockets and empty stomachs. This article uses common pool resource theory to analyze the origins and workings of collective fishing agreements in the Brazilian Amazon floodplains. As commercial fisheries expanded in the mid-1990s, experiences in community-managed lakes emerged in several locations, as a promising example of participatory grassroots management. Findings show that agreements yield considerable improvements, although their effectiveness is threatened by the weak vigilance and monitoring and by the lack of effectiveness of land tenure regulation. The article suggests that governmental agencies should support these agreements by developing (or adapting) mechanisms aiming at the decentralization of public decisions and management. Their failure may lead to changes in ecological processes, reduction of fishing stocks, and social-environmental conflicts.

Courses timetabling has been one of the main problems for planning, maintaining and optimizing educational institutions. However, the intriguing mathematical problem which usually result from the attempt of promoting optimal courses timetabling has prevented a widely dedication of education managers to this area. The present paper aims to summarize the usefulness of approximate techniques (e:g: genetic algorithms) for dealing with courses timetabling. In particular, the successful application of the resulting algorithm in a Brazilian university center is highlighted.