Navegando por Autor "SOUZA, Paulo Jorge de Oliveira Ponte de"

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Acesso aberto (Open Access)
Albedo da cultura da soja em área de avanço da fronteira agrícola na Amazônia
(2010-01) SOUZA, Paulo Jorge de Oliveira Ponte de; RIBEIRO, Aristides; ROCHA, Edson José Paulino da; LOUREIRO, Renata Silva de; BISPO, Carlos José Capela; SOUSA, Adriano Marlisom Leão de
Soybean expansion in the Amazon has been increasing considerably in recent years, the consequences of which can be serious environmental impacts. In this paper the soybean albedo (Glycine Max (L.) Merryl) was evaluated, which was planted in natural field conditions in Paragominas city (PA), a region representative of agricultural expansion in Amazon. A direct relationship was observed between soybean albedo and its leaf area index (LAI), showing a daily maximum value between 0.24 and 0.25 associated to a LAI of 7.17, when soybean has accumulated 1297.62 degree-days. It was found that the most critical phase of the crop, based on change in surface albedo, is the fruitification phase, when albedo shows a maximum mean value of 0.23 (± 0.0007). Empirical models were fitted to simulate the daily variation of the albedo as a function of LAI and soil humidity during the cycle, and to simulate the diurnal variation of the albedo as a function of solar elevation, for each soybean phase.
Acesso aberto (Open Access)
Efeitos de um evento de friagem nas condições meteorológicas na Amazônia: um estudo de caso
(Instituto Nacional de Pesquisas da Amazônia, 2004-12) SOUZA, Paulo Jorge de Oliveira Ponte de; ROCHA, Edson José Paulino da; FISCH, Gilberto Fernando; KRUIJT, Bart; RIBEIRO, João Batista Miranda
Observations of the influence of a Cold Spell phenomena on meteorological variables and on energy and CO2 fluxes were made in a forest site near Ji-Paraná, Rondonia, during June 2001. Friagem caused a diminution of 35% at air temperature. A reduction of 75 W.m-2 from normal days (200 W.m-2) to cold days (125 W.m-2) in the mean incoming solar radiation was also observed. During the Cold Spell days, both sensible heat (H) and latent heat fluxes (LE) showed a decrease in their mean daily value, showing a difference from normal days of 8 e 34%, respectively. The CO2 concentration remained constant, without increase during the night, due to the windy condition of cold days. During normal days the mean diurnal CO2 flux (-2,44 mmol m-2 s-1) was lesser than that one at phenomena days (-5,78 mmol m-2 s-1), while the mean nocturnal fluxes were +1,77mmol m-2 s-1 e +2,83mmol m-2 s-1 during normal and cold days, respectively.
Acesso aberto (Open Access)
Evapotranspiration from Remote Sensing to Improve the Swat Model in Eastern Amazonia
(Universidade Federal do Pará, 2015-12) SOUSA, Adriano Marlisom Leão de; VITORINO, Maria Isabel; CASTRO, Nilza Maria dos Reis; BOTELHO, Marcel do Nascimento; SOUZA, Paulo Jorge de Oliveira Ponte de
In this study, we estimated the evapotranspiration from orbital images - MODIS (Moderate Resolution Imaging Spectroradiometer) for assimilation in the hydrological modeling of the SWAT (Soil Water Assessment Tools) model. The data used include the period between October 2003 and December 2006 of the sub-basin of the Lajeado River, located in the Tocantins-Araguaia River basin in Tocantins state. Overall, the results of the use of heat flows estimated by remote sensors in the SWAT model can be considered satisfactory. The values of the COE (coefficient of efficiency of Nash-Sutcliffe) ranged from -0.40 to 0.91 in the comparison with the daily flow data and from 0.17 to 0.77 with the monthly flow data, with the assimilation of evapotranspiration from orbital images. These results indicate benefit to the model adjustment due to improvement in the data assimilated of approximately 0.91 in the COE on daily scale and 0.60 in the CEO on monthly scale.
Acesso aberto (Open Access)
Impactos do avanço da soja no balanço de radiação no leste da Amazônia
(Instituto Nacional de Pesquisas da Amazônia, 2013-06) SOUZA, Paulo Jorge de Oliveira Ponte de; ROCHA, Edson José Paulino da; RIBEIRO, Aristides
The deforestation of the Amazon, especially for pasture use, has been explored by several researchers who have pointed out as a consequence, serious environmental problems. The continuous expansion of agriculture on areas of cattle ranching in the Amazon, as well as on native areas, must be seen with caution since few studies have been conducted in order to investigate which probable environmental impacts can be generated due to the presence of soybean monoculture in the region. This study evaluates the local impacts of the replacement of forest by soybean (Glycine max (L.) Merrill) on radiation balance components in an area that represents the agricultural border advancement in Amazonia. A micrometeorological experiment was installed in an area of soybean cultivation in Paragominas-PA and data from forest ecosystems were collected in Caxiuanã forests located in Melgaço-PA both during 2006 and 2007. During the soybean growing season the mean impact found in net radiation represented a reduction of 17.9% of the value commonly observed in the forest. During the off-season the impact on net radiation was 15.5%. Principal mechanisms that control these impacts were associated with the high soybean albedo and high loss of long wave radiation. Although the greatest impact occurs during the crop growing season, the time of occurrence of this negative effect is restricted to only 1/3 of the year, which leads to a higher impact of the off-season on energy balance in cumulative terms.
Acesso aberto (Open Access)
Radiation balance in a soybean ecosystem in the Amazon
(2010-12) SOUZA, Paulo Jorge de Oliveira Ponte de; ROCHA, Edson José Paulino da; RIBEIRO, Aristides; SOUZA, Everaldo Barreiros de
The continuous advance of the agricultural border in the Amazon has been worrying the scientific community due to the possible environmental impacts caused by this change in land use. The present work evaluated the behavior of the radiation balance components over the soybean crop (Glycine Max (L.) Merryl) in an Amazon area of continuous advance of the agricultural border. The radiation components were continuously monitored during the soybean cycle in 2006 and 2007 in an area of 200 ha. The soybean cultivation in the Amazon presented an abrupt change in the radiation balance components, with the consequent reduction in the energy available to the environment due to the increase in the surface reflection. There was a significant contribution of the diffuse radiation component in the soybean interception during cloudy conditions, even under incomplete canopy covering. Moreover, after the canopy closure, a similar interaction between soybean and solar radiation occurs, regardless of the cloud condition.
Acesso aberto (Open Access)
Sazonalidade no balanço de energia em áreas de cultivo de soja na Amazônia
(2012) SOUZA, Paulo Jorge de Oliveira Ponte de; RIBEIRO, Aristides; ROCHA, Edson José Paulino da; FARIAS, José Renato Bouças; SOUZA, Everaldo Barreiros de
It was investigated the energy balance in a soybean crop (Glycine max (L.) Merrill) grown in areas of advance of agricultural border in the Amazon. The Bowen ratio technique was used to obtain energy balance components. During the most part of the crop growing season, most of the energy was consumed as latent heat, especially during the flowering and fruiting stages. Such characteristic was related to the high leaf stomatal conductance of soybean as well as to the water availability in the region. At the harvest there was an inversion in the energy partitioning, with more energy being used for heating the air (79% of the net radiation). During the off-season there was 75% reduction in the LE and significant increase in the H (180%) compared to the values found during soybean growing season.
Acesso aberto (Open Access)
Simulation of soybean growth and yield under northeastern Amazon climatic conditions
(2011-06) SOUZA, Paulo Jorge de Oliveira Ponte de; FARIAS, José Renato Bouças; ABREU, José Paulo Mourão de Melo e; RIBEIRO, Aristides; ROCHA, Edson José Paulino da; BOTELHO, Marcel do Nascimento; SOUSA, Adriano Marlisom Leão de
The objective of this work was to parameterize, calibrate, and validate a new version of the soybean growth and yield model developed by Sinclair, under natural field conditions in northeastern Amazon. The meteorological data and the values of soybean growth and leaf area were obtained from an agrometeorological experiment carried out in Paragominas, PA, Brazil, from 2006 to 2009. The climatic conditions during the experiment were very distinct, with a slight reduction in rainfall in 2007, due to the El Niño phenomenon. There was a reduction in the leaf area index (LAI) and in biomass production during this year, which was reproduced by the model. The simulation of the LAI had root mean square error (RMSE) of 0.55 to 0.82 m2 m-2, from 2006 to 2009. The simulation of soybean yield for independent data showed a RMSE of 198 kg ha‑1, i.e., an overestimation of 3%. The model was calibrated and validated for Amazonian climatic conditions, and can contribute positively to the improvement of the simulations of the impacts of land use change in the Amazon region. The modified version of the Sinclair model is able to adequately simulate leaf area formation, total biomass, and soybean yield, under northeastern Amazon climatic conditions.
Acesso aberto (Open Access)
Solar radiation use efficiency by soybean under field conditions in the Amazon region
(2009-10) SOUZA, Paulo Jorge de Oliveira Ponte de; RIBEIRO, Aristides; ROCHA, Edson José Paulino da; FARIAS, José Renato Bouças; LOUREIRO, Renata Silva de; BISPO, Carlos José Capela; SAMPAIO, Leila Sobral
The objective of this work was to evaluate the efficiency of soybean (Glycine max) in intercepting and using solar radiation under natural field conditions, in the Amazon region, Brazil. The meteorological data and the values of soybean growth and leaf area were obtained from an agrometeorological experiment carried out in Paragominas, Pará state, during 2007 and 2008. The radiation use efficiency (RUE) was obtained from the ratio between the above-ground biomass production and the intercepted photosynthetically active radiation (PAR) accumulated to 99 and 95 days after sowing, in 2007 and 2008, respectively. Climatic conditions during the experiment were very distinct, with reduction in rainfall in 2007, which began during the soybean mid-cycle, due to the El Niño phenomenon. An important reduction in the leaf area index and biomass production was observed during 2007. Under natural field conditions in the Amazon region, the values of RUE were 1.46 and 1.99 g MJ-1 PAR in the 2007 and 2008 experiments, respectively. The probable reason for the differences found between these years might be associated to the water restriction in 2007 coupled with the higher air temperature and vapor pressure deficit, and also to the increase in the fraction of diffuse radiation that reached the land surface in 2008.
Acesso aberto (Open Access)
Water requirement estimate for the reproductive period of mango orchads in the northeast of the state of Pará, Brasil
(Universidade Federal do Pará, 2016-09) SOUZA, Paulo Jorge de Oliveira Ponte de; RODRIGUES, Juliana Chagas; SOUSA, Adriano Marlisom Leão de; LIMA, Renata Trindade de; ROCHA, Edson José Paulino da; ORTEGA-FARIAS, Samuel
The aim of this study was to estimate the water consumption in mango orchard during its phenological stages in the northeastern of the State of Pará, Brazil. For this purpose, it was installed and instrumented a micrometeorological tower in a mango orchard, cv. Tommy Atkins, of 22 years old, with data collected during the crops of 2010/2011 and of 2011/2012. The actual crop evapotranspiration was estimated from the energy balance using the Bowen ratio technique. The crops were subjected to different weather conditions, consequently, some differences in the Bowen ration values were observed. The evapotranspiration suffered influences of meteorological conditions during the period. The actual crop evapotranspiration during its reproductive period ranged between 402.9 and 420 mm with a mean daily water consumption of 3.8 mm at flowering, of 4.25 mm at fruit fall, of 3.56 mm at fruit formation, of 3.0 mm at fruit maturation and of 3.73 mm for the whole period.