839 resultados para Suelos
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Economía institucional: propuesta metodológica para el análisis de la formación de precios agrícolas
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Uma das áreas mais promissoras para o estudo das sociedades pré-colombianas complexas na bacia do rio Amazonas é a área do baixo curso dos rios Tapajós, Trombetas e Nhamundá. Há relatos escritos sobre os Konduri e os Tapajós, apresentando informações sobre a sua organização social regional, padrões de comércio, a abundância de alimentos, e o mundo material. Assim, evidências arqueológicas – sítios imensos, solos antrópicos, e belos artefatos – podem ser contrastadas com a informação escrita. Estes ricos depósitos culturais estão desaparecendo a um ritmo alarmante, à medida em que os centros urbanos crescem e se expande a agricultura na região. Apesar desta situação, pouca pesquisa arqueológica tem sido realizada na área, especialmente quando se trata de investigar os antigos padrões de assentamento e redes de trocas. Nos últimos anos, temos realizado pesquisas na bacia do baixo rio Tapajós. O registro arqueológico indica que a cerâmica mostrando forte semelhança estilística forte com a encontrada no grande sítio central está espalhada por pelo menos 90 quilômetros ao sul da presente cidade de Santarém. Este artigo apresenta os resultados de uma pesquisa regional realizada nas proximidades de Santarém, no planalto de Belterra e Alter do Chão, oferecendo uma análise preliminar do sistema de assentamentos na região.
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O estudo tem como objetivo avaliar e analisar o manejo da agrobiodiversidade em geoformas de restingas a partir da adaptabilidade da agrobiodiversidade praticada e da função que desempenham nas estratégias econômicas das famílias produtoras ribeirinhas. A relativa estabilidade das geoformas de restingas em função das erosões e inundações e seu grande potencial agro-biológico natural, explicam sua ocupação e uso intensivo dos solos desde muito antes do descobrimento e colonização da Amazônia pelos europeus (espanhóis e portugueses). A adaptabilidade da biodiversidade ribeirinha, como estratégia para produzir, manejar e conservar a diversidade dos recursos agrícolas, agroflorestais e outros recursos da agrobiodiversidade amazônica nas diferentes unidades de produção ou agroecosistemas (hortas, quintais, capoeira e bosques) de propriedade familiar, tem contribuído para alcançar auto-suficiência alimentar durante o ano e, principalmente, enfrentar ou diminuir riscos ocasionados por grandes inundações e pelo mercado (instabilidade de preços). O trabalho de campo foi realizado na várzea amazônica peruana, especificamente no Setor Muyuy, no sudeste da cidade de Iquitos.
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All trees with diameter at breast height dbh >= 10.0 cm were stem-mapped in a "terra firme" tropical rainforest in the Brazilian Amazon, at the EMBRAPA Experimental Site, Manaus, Brazil. Specifically, the relationships of tree species with soil properties were determined by using canonical correspondence analyses based on nine soil variables and 68 tree species. From the canonical correspondence analyses, the species were grouped into two groups: one where species occur mainly in sandy sites, presenting low organic matter content; and another one where species occur mainly in dry and clayey sites. Hence, we used Ripley's K function to analyze the distribution of species in 32 plots ranging from 2,500 m(2) to 20,000 m(2) to determine whether each group presents some spatial aggregation as a soil variations result. Significant spatial aggregation for the two groups was found only at over 10,000 m(2) sampling units, particularly for those species found in clayey soils and drier environments, where the sampling units investigated seemed to meet the species requirements. Soil variables, mediated by topographic positions had influenced species spatial aggregation, mainly in an intermediate to large distances varied range (>= 20 m). Based on our findings, we conclude that environmental heterogeneity and 10,000 m(2) minimum sample unit sizes should be considered in forest dynamic studies in order to understand the spatial processes structuring the "terra firme" tropical rainforest in Brazilian Amazon.
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The enrichment of an organic compound with biofertilizers of microorganisms (solubilizing phosphorus bacteria, BSF) can improve the properties of phosphate fertilizers applied to soils to increase nutrient availability. The experimental design was randomized complete blocks with a factorial 4x2 +1 arrangement of treatments: 1) four sources of phosphorus: phosphate rock, natural phosphate, triple superphosphate (TSP) and Cuban phosphate rock; 2) two sources of bio-fertilizer prepared from filter cake (cane waste) enriched with microorganisms and no enrichment; 3) and an absolute control (no filter cake or fertilizer); repeated three times. Data was analyzed with ANOVA and treatment means were compared using Tukey (p <= 0.05). Assessments of available P (Bray-2 and Oniani methodology) and the quantification of total and solubilizing bacteria and fungi in the soil were performed 30, 60 and 90 d after starting the experiment. After 60 d, the population of BSF was lower in the control (p <= 0.05) and the content of P (Bray-2) was higher for SFT (p <= 0.01). The application of the bio-fertilizer increased the P content compared to the control. At 90 d P (Bray-2) increased with the SFT treatment, which also increased (p P in the soil at 60 and 90 d regardless of the presence of microorganism-enriched bio-fertilizer. The use of filter cake enriched with microorganisms associated with different sources of P, and applied to the soil with a high content of P, did not change the soil populations of total and solubilizing bacteria and fungi in the short term. TSP promoted the highest levels of P in the soil, irrespective of the presence of the organic compound enriched with P solubilizing microorganisms.
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The objective of the research was to define the classes of use capacity of 2403.25 ha in the basin of the Corriente del Lobo - Itatinga (SP), (22°03'56" to 22°59'12" of latitude S and 48°38'47" to 48°41'25" of longitude W Gr.). The soil use capacity was obtained by using the SIG IDRISI 32 crossing the documents of steepness and soils and the document of judgment of classes of soil use capacity and of the utilitarian rising of the physical milieu. The classes and subclasses areas of use capacity presented the following values: IIIa - 68.60 ha (2.85%), IIIe,s - 1919.15 ha (79.86%); IIIe - 210.60 ha (8.76%); IVe - 3.38ha (0.14%); IVe,s - 157.42 ha (6.55%) and VIe,s - 44.10 ha (1.84%). The lands of the basin were distributed in three classes (III, IV and VI) and six subclasses but the biggest extension (79.9%) belonged to the subclass IIIe,s. The modules of the IDRISI allowed to discriminate, mapping and to quantify quickly the soil use capacity of the areas of classes and subclasses in the basin.
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The increasing expansion of agricultural activities, without considering the potential and limitations of soils is a potential source of environmental degradation. Thus, the present study assessed the variation of use and occupation in 49 years, between 1962 and 2011 scenarios of watershed of São Caetano - Botucatu (SP). geoprocessing techniques were used in this study. In a Geographic Information System (GIS) - IDRISI – it was integrated information from IBGE digital cards, scale 1:50,000, plus aerial photographs (1962) and satellite images LANDSAT - 5 (2011). In the study area, we can view the progress of the urban area, which in 1962 was not present in the watershed. In 2011, the urban area occupied 21.37% of the total area. Even with this breakthrough occurring in the period of 49 years, there was an increase in the area of natural vegetation, which once occupied only 12.33% of the area (1962), and in 2011 represents 25% of the total area of the watershed, showing an increase in awareness on the importance of preserving nature. Thus, we can conclude that the analysis tools based on GIS enabled us to analyze variations in space and time and to propose alternatives to the correct use and occupation of land.