RESUMO:Os quintais agroflorestais são sistemas de uso da terra com função de proteção e produção, contribuindo de forma muito especial para a segurança alimentar de agricultores familiares. Assim, objetivou-se estudar a agrobiodiversidade de quintais agroflorestais em comunidades rurais do município de Bonito, Estado do Pará, Brasil. Os dados foram coletados em 24 quintais agroflorestais, em quatro comunidades deste município, com auxílio de entrevistas estruturadas e observação direta, seguida da realização de inventário florístico a 100% de intensidade. Foram estudados os seguintes aspectos: a composição florística, a estrutura horizontal e os índices de valor de preferência, bem como a classificação dos quintais por análise de agrupamento. As famílias Annonaceae, Arecaceae e Myrtaceae foram as que obtiveram maior número de espécies. As espécies frutíferas Cocus nucifera, Musa spp., Citrus limonia e Anacardium occidentale são as mais frequentes nos quintais agroflorestais estudados e apresentam os maiores valores de preferência. Os quintais apresentam riqueza e diversidade consideradas altas. Estas áreas são manejadas com baixo nível tecnológico, de forma tradicional e são compostas principalmente por espécies frutíferas, que fazem parte do hábito alimentar de agricultores familiares.

Soil microbial biomass (SMB) plays an important role in nutrient cycling in agroecosystems, and is limited by several factors, such as soil water availability. This study assessed the effects of soil water availability on microbial biomass and its variation over time in the Latossolo Amarelo concrecionário of a secondary forest in eastern Amazonia. The fumigation-extraction method was used to estimate the soil microbial biomass carbon and nitrogen content (SMBC and SMBN). An adaptation of the fumigation-incubation method was used to determine basal respiration (CO 2 -SMB). The metabolic quotient (qCO 2 ) and ratio of microbial carbon:organic carbon (C MIC :C ORG ) were calculated based on those results. Soil moisture was generally significantly lower during the dry season and in the control plots. Irrigation raised soil moisture to levels close to those observed during the rainy season, but had no significant effect on SMB. The variables did not vary on a seasonal basis, except for the microbial C/N ratio that suggested the occurrence of seasonal shifts in the structure of the microbial community.

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RESUMOEste trabalho teve como objetivo avaliar o teor de cálcio e o efeito do ataque da lagarta H. grandella em plantas jovens de mogno (S. macrophylla), cultivadas em função de diferentes épocas de (1975). O delineamento experimental foi inteiramente casualizado (DIC), as variáveis utilizadas para avaliação foram a susceptibilidade do mogno ao ataque da broca H. grandella, comprimento da galeria da broca e o teor de cálcio no caule. Foi realizado um DIC com cinco doses de cálcio, cinco repetições cada, e duas épocas de inoculação da broca. Utilizou-se regressões lineares simples para interpretação dos dados. Através da pesquisa, conclui-se que a aplicação de doses de cálcio, em solução nutritiva, reduziu o comprimento da galeria de infecção e exerce eficiente ação no controle do ataque da praga em plantas de mogno. palavRaS-chavE:Swietenia macrophylla e Hypsipyla grandella. Effect of the calcium in the control of the Hypsipila grandella in young mahogany cultivated in hidroponics systemaBSTRacT The objective of this research was to evaluate the leaf level of calcium and the effect attack by caterpillar H. grandella to young mahogany (S. macrophylla) plants cultivated in a nutritive solution. This solution was that proposed by Hoagland and Arnon modified by Epstein (1975). The experiment was carried out in the greenhouse of the Federal Rural University of Amazonas (UFRA), at Belem, Para, from September 2004 to February 2005. A split plot experimental desing with five replicates was used. The plots were five doses of calcium (0, 80, 160, 240, ) and the subplots two times of harvesting the plants (189 e 211 days after planting) for the variables sensitivity of mahogany seedlings to attack of the drill, gallery length and stem level of calcium. Results showed the calcium decreased gallery length of infection suggesting that it was efficient to control the attact of plague to mahogany seedlings. kEy wORdS: Swietenia macrophylla, Hypsipyla grandella, calcium, plaguel.

Homegardens are considered as an alternative to preserve and/or restore the fertility and productivity of degraded soils. The assessment of changes in soil chemical properties resulting from land use and management is important to understand these changes and allow a rational intervention to ensure production on a sustainable basis. Thus, the aim of this study was to evaluate the soil chemical properties of homegardens and other systems of land use, as well as to identify the factors that influence fertility in areas of family farming in the municipality of Bonito, Eastern Amazon. Three soil samples were collected from secondary forest, cassava (Manihot esculenta) monoculture, silvopastoral systems and homegardens, from the depth range of 0-20 cm, and were evaluated in a completely randomized design with 12 treatments and three replications. The data were subjected to analysis of variance with the Kruskal-Wallis test, correlation analysis and principal component analysis. The variables studied, except Mg and Ca, were influenced by the soil cover. The homegardens, agricultural monoculture and silvopastoral systems were similar to the secondary forest in terms of nutrient cycling, with the exception of one 35-year-old homegarden, where the levels of P and K were higher. The soil fertility was explained by three factors: soil nutrients and salinity (P, K and Na); soil acidity and aluminum toxicity (Ca, Al, Mg, and pH); and by soil organic matter (SOM).