Soil samples were collected in six South American countries in a total of 71 different 1 ha forest plots across the Amazon Basin as part of the RAINFOR project. They were analysed for total and exchangeable cations, C, N, pH with various P fractions also determined. Physical properties were also examined and an index of soil physical quality proposed. A diverse range of soils was found. For the western areas near the Andean cordillera and the southern and northern fringes, soils tend to be distributed among the lower pedogenetic levels, while the central and eastern areas of Amazonia have more intensely weathered soils. This gives rise to a large variation of soil chemical and physical properties across the Basin, with soil properties varying predictably along a gradient of pedogenic development. Nutrient pools generally increased slightly in concentration from the youngest to the intermediate aged soils after which a gradual decline was observed with the lowest values found in the most weathered soils. Soil physical properties were strongly correlated with soil fertility, with favourable physical properties occurring in highly weathered and nutrient depleted soils and with the least weathered, more fertile soils having higher incidence of limiting physical properties. Soil phosphorus concentrations varied markedly in accordance with weathering extent and appear to exert an important influence on the nitrogen cycle of Amazon forest soils

Abstract. Soil samples were collected in six South American countries in a total of 71 different 1 ha forest plots across the Amazon Basin as part of the RAINFOR project. They were analysed for total and exchangeable cations, C, N, pH with various P fractions also determined. Physical properties were also examined and an index of soil physical quality proposed. A diverse range of soils was found. For the western areas near the Andean cordillera and the southern and northern fringes, soils tend to be distributed among the lower pedogenetic levels, while the central and eastern areas of Amazonia have more intensely weathered soils. This gives rise to a large variation of soil chemical and physical properties across the Basin, with soil properties varying predictably along a gradient of pedogenic development. Nutrient pools generally increased slightly in concentration from the youngest to the intermediate aged soils after which a gradual decline was observed with the lowest values found in the most weathered soils. Soil physical properties were strongly correlated with soil fertility, with favourable physical properties occurring in highly weathered and nutrient depleted soils and with the least weathered, more fertile soils having higher incidence of limiting physical properties. Soil phosphorus concentrations varied markedly in accordance with weathering extent and appear to exert an important influence on the nitrogen cycle of Amazon forest soils.

-The objective of this study was to evaluate the development of grass Paspalum millegrana Schrad propagated through seeds and tillers, subjected to different levels of water and phosphorus to be used in erosion control on slopes. The experimental trial was conducted in greenhouse with propagation of tillers and seeds of Paspalum grass, at the Federal University of Sergipe, São Cristóvão, Brazil. The design was the completely randomized design with sixteen treatments and four replications, arranged in a factorial scheme corresponding to (0, 100, 200, 300 and 400 mg kg -1 ), two water contents in the soil (60% and 100% of total pore volume) filled with water and two types of propagation (tillers and seeds). Plants were harvested at the end of four months of conducting the experiment and evaluated the following variables: number of tillers (NT), number of inflorescences (NI), Shoot Length (SL), Root Length (RL), Shoot Dry Weight (SDW) and Root Dry Weight (RDW). The phosphorus and water levels interacted positively with the variables studied and showed that this grass, presented biotech important features like good tillering, and the consequent formation of dense aerial biomass and root required for slope protection against erosion. The specie Paspalum millegrana showed a better development among the variables analyzed under conditions of less water availability with 60% VTP and the best responses of the simple superphosphate dosages were between 200 and 300 mg kg -1 .

Esse trabalho tem como objetivo identificar a compreensão dos ribeirinhos sobre o processo de degradação ambiental no Baixo São Francisco com ênfase na retirada da vegetação ciliar e nos processos erosivos. Para obtenção dos dados foram entrevistados 260 (duzentos e sessenta) pescadores, utilizando-se a técnica de entrevista semi-estruturada. De acordo com os entrevistados têm ocorrido mudanças no regime hídrico do rio levando à evolução dos processos erosivos, sobretudo nas últimas três décadas. Estas alterações são fruto de políticas de desenvolvimento que ao construir barragens no canal do rio para a geração de energia, potencializaram a problemática ambiental, afetando diretamente a população ribeirinha.

Artigo enviado em 12/01/2017, aceito em 26/04/2017 e publicado em 07/07/2017. RESUMO:A predição de eventos erosivos é de grande importância nas terras do Baixo São Francisco-BSF, que apresentapráticas de manejo inadequado vem provocando degradação das áreas cultivadas e matas ciliares com consequente avanço de processos erosivos nas margens do rio. A Equação Universal de Perda de Solos (EUPS) é um modelo queutiliza dados pluviométricos, tipos de solos, declividade do terreno e uso do solo, para estimar a quantidade de solo perdida em uma determinada área. O objetivo desse trabalho foi estimar e avaliar as perdas de solo no Baixo São Francisco sergipano. O BSF ocupa uma área de 3.201.300 ha, se iniciando em Paulo Afonso-BA, com sua foz entre Piaçabuçu-AL e Brejo Grande-SE. O trecho no estado de Sergipe ocupa uma área de 738.754ha, onde foi estimada a perda de solos. Nas áreas de pastagem, que ocupam 76% do BSF, foram encontrados valores que variaram de 0 a 0,33 t ha -1 ano -1 de perda de solo. Somente 0,1% da área estudada apresentou alto risco de erosão, justificado pela predominância de áreas com ocorrência de baixa erosividade, associada à uma cobertura do solo mais conservacionista como as pastagens. A baixa expressividade das perdas de solo se mostra resultante da combinação de vários fatores, com ênfase na baixa erosividade. Palavras-Chave -Erosão, EUPS, SIG Abstract -The prediction of erosive events have this great importance in the lands of lower São Francisco-LSF, where practices of inadequate management have led to degradation of cultivated areas and riparian forests, with consequent advance of erosive processes along the river banks. The Universal Soil Loss Equation (USLE) is a model that uses pluviometric data, soil types, land slope and land use, to calculate how much soil loss in a given area in a year. The objective of this work was to estimate and to evaluate the soil losses in the Lower São Francisco of Sergipe state. The LSF occupies an area of 3,201,300 ha, from Paulo Afonso-BA, to the mouth of the river between Piaçabuçu-AL and Brejo Grande-SE. The stretch in the state of Sergipe occupies an area around 738.754ha, where soil loss was calculated using ArcGis 9.0 software. The pasture areas are predominant in the Basin, occupying more than half of the LSF (76.26%), values ranging from 0 to 0.33 t ha-1 year -1 of soil loss.Only 0.1% of the studied area presented a high risk of erosion, justified by the predominance of areas with low erosivity, associated to a more conservationist soil cover mostly by pastures.The low expressiveness of soil losses is shown by the combination of several factors, with emphasis on low erosivity.