Navegando por Assunto "Fronteira agrícola"

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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)
Balanço de água em área de cultivo de soja no Leste da Amazônia
(Universidade Federal do Pará, 2007) BISPO, Carlos José Capela; RIBEIRO, Aristides; http://lattes.cnpq.br/8652338930029697; ROCHA, Edson José Paulino da; http://lattes.cnpq.br/2313369423727020
The expansion of the agricultural frontier, driven mainly by soy cultivation (Glycine max (L) Merrill), covers a large regional extent and is highly important to understanding the changing face of Amazonia. A field observation experiment was established to study water balance components of the soy agriculture ecosystem and analyze the impact of the water balance associated with forest conversion. The experiment also evaluated the crop’s need for water according to its development phase. For the water balance study, the BRS Candeia cultivar was used along with its respective phenological phases. The experiment measured soil water storage, precipitation, plant cover water interception, superficial drainage of soil water, evapotranspiration (Etc), and water content retained by the soy plant. Water infiltration in the soil was also measured. Interception and superficial drainage were 45,9% and 1% of the precipitation, respectively. The greatest evapotranspiration occurred during the flowering phase (R1-R2) with a gradual decline in values until crop harvest and a cycle average of 3,80mm.day-1, which was very similar to that found in forest. The period between the vegetative phase (V) and fruiting (R3-R4) was when the plant presents the greatest percentage of water, declining gradually during the grain-forming phase (R5). Overall, no water deficiency occured in the mean soil water balance. Precipitation was greater than the amount necessary to compensate for evapotranspiration and supply adequate water storage, creating a surplus of water in the soil.
Acesso aberto (Open Access)
Fronteira agrícola e conflitos territoriais nas Amazônias Brasileiras: a expansão do agronegócio da soja e seus efeitos no planalto de Santarém, Pará-Amazônia-Brasil
(Associação dos Geógrafos Brasileiros, 2020) BARROS, Márcio Júnior Benassuly; LOPES, Luís Otávio do Canto; LAURENT, François; COELHO, Andréa dos Santos
The research presented in this article aims to analyze the expansion of the agricultural frontier and the territorial confl icts generated by the arrival of soybeans on the Santarém plateau, in the state of Pará (Amazonia, Brazil). It is a case study, the methodology is based on two approaches: the synthesis of the literature and the fi eld work carried out over the past two decades. The research followed the following stages: state of the bibliographic art, fi eld work, focusing on direct observations, non-directive interviews with community members, local leaders, photographic archives, remote sensing and mapping. The main results show that the introduction of soybean in the municipality of Santarém, from 1996, led to deep territorial transformations, particularly for the communities lead into a territorial confl ict, faced with the expansion of the agricultural frontier.
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)
A reprodução sócio-econômica e produtiva do campesinato no Sudeste paraense: o Assentamento Palmares II, Parauapebas/PA
(Universidade Federal do Pará, 2010-06-24) SOUZA, Haroldo de; HURTIENNE, Thomas Peter; http://lattes.cnpq.br/7133222063843073
The southeast region of Pará State was the main stage of one of the strongest and most pungent occupation and colonization process ever seen in the Amazonian area as a whole. The high number of migrant peasant workers along the twentieth century, especially during the decades of 1970´s, 1980´s and 1980´s, occurred straightly together with another series of plans strategically thought out in order to colonize the area such as extensive agriculture, mining and energy generation projects. Due to the complex situation found in the regional agricultural system, nowdays this scenery is marked a high level of conflict, which brings up the region subjects to academic debate as being a frontier. From middle 90's conflicts and contestation has changed due to the adoption of settlement of agricultural laborers projects and the elaboration of politics aiming the improvement of self-sustainable familiar agriculture. Such facts made it possible for us to think in new sort of conflicts and possibilities of social and economic reproduction among those settled peasant communities. The current study, following the context described above, is therefore focused on the present possibilities of social and economic reproduction of the Palmares II settlement community, which is located at the neighborhood of the city of Parauapebas/PA, aiming to understand the real factors which are either allowing or not the Frontier Thesis to be disrupted and, in contrast, allowing a certain life stabilization to the settled peasants communities. Far beyond trying to evidence and prove the existence of new production system ways put into practice by the Palmares II settlement workers, the present work intend to disclose what are the economic, social and politics factors which are being important to keep improving the creation of possibilities on the peasant communities reproduction strategies.
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.