Calibración del número N de la curva de escurrimiento en una cuenca agropecuaria de 116 km2 de la provincia de Buenos Aires, Argentina

535-541In the mountainous area of Buenos Aires, Argentina, an increase in precipitation and in cultivated area has contributed to generating excessive runoff that has had severe impact on the region and on soil water erosion. The rain-runoff ratio in this region can help estimate the effects of floods. The local values of the runoff curve number (N) were calculated for the basin of the Arroyo Videla (Buenos Aires, Argentina), and its relationship to rainfall events was studied parting from daily rain data and runoff volumes. Values of 51 to 99 were obtained, and the most frequent were between 60 and 90. The relationship between N and precipitation exhibited a standard pattern that allowed adjusting an asymptotic value of 57. Rains less than 15 mm were associated with N between 85 and 90, while rains between 15 and 85 mm were related to N of 60 to 85. There was concordance between intermediate observed N and tabulated values of this parameter associated with each plant cover. This highlights the importance of obtaining local values of the studied variable to appropriately implement the method in basins of 100 km2

Calibración del número N de la curva de escurrimiento en una cuenca agropecuaria de 116 km2 de la provincia de Buenos Aires, Argentina

535-541In the mountainous area of Buenos Aires, Argentina, an increase in precipitation and in cultivated area has contributed to generating excessive runoff that has had severe impact on the region and on soil water erosion. The rain-runoff ratio in this region can help estimate the effects of floods. The local values of the runoff curve number (N) were calculated for the basin of the Arroyo Videla (Buenos Aires, Argentina), and its relationship to rainfall events was studied parting from daily rain data and runoff volumes. Values of 51 to 99 were obtained, and the most frequent were between 60 and 90. The relationship between N and precipitation exhibited a standard pattern that allowed adjusting an asymptotic value of 57. Rains less than 15 mm were associated with N between 85 and 90, while rains between 15 and 85 mm were related to N of 60 to 85. There was concordance between intermediate observed N and tabulated values of this parameter associated with each plant cover. This highlights the importance of obtaining local values of the studied variable to appropriately implement the method in basins of 100 km2

Efeitos da leucena e da adubação NPK sobre a cultura do feijão no cerrado.

An experiment was carried out in a poor cerrado soil at Patrocinio, state of Minas Gerais, in order to determine the effect of Leucaena leucocphala, as a green manure, and chemical fertilization on the yield of beans (Phaseolus vulgaris). Treatments included leucena plus a 2 x 2 x 2 factorial, as levels of 0 and 40kg/ha of N (as ammonium sulfate), 0 and 70kg/ha of P2O5 (as ordinary super-phosphate), and 0 and 60 kg/ha of K2O (as potassium chloride). Additional treatments were 0-0-0 and 40-70-60- kg/ha of N-P2O5-k2O, both without the green manure. The leucena and the NPK fertilization had the same effect, increasing the bean yield from 83 to 350 kg/ha. With leucena, the superphosphate had the greatest effect, followed by the nitrogenous fertilizer. The complete chemical fertilization associated with the green manuring resulted in the hihest yield of 900 kg/ha

Espermatogênese de tambaqui (Colossoma macropomum) criado em cativeiro.

No Amazonas, o constante aumento da pressão da pesca extrativista sobre os estoques de populações naturais de peixe, associado ao aumento da demanda pelo pescado, vêm contribuindo para a propagação da piscicultura no Estado. Neste cenário destaca-se o tambaqui, representando o melhor candidato nativo para a piscicultura intensiva na Amazônia e em outras áreas do Brasil. Devido a crescente relevância desta espécie na aqüicultura da região Norte e nacional, o presente trabalho propõe-se a detalhar o processo espermatogênico de tambaquis criados em cativeiro, através de estudos histológicos e de estimativas dos níveis plasmáticos de esteróides sexuais

Bacterial retention in three soils of the Rolling Pampa, Argentina, under simulated rainfall

Fil: Behrends Kraemer, Filipe B. Universidad de Buenos Aires (UBA), Facultad de Agronomía, Cátedra de Manejo y Conservación de Suelos; Argentina.Fil: Chagas, Celio I. Universidad de Buenos Aires (UBA), Facultad de Agronomía, Cátedra de Manejo y Conservación de Suelos; Argentina.Fil: Irurtia, Carlos. Instituto Nacional de Tecnología Agropecuaria (INTA); Argentina.Fil: Garibaldi, Lucas Alejandro. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. INIBIOMA-CONICET. Laboratorio Ecotono; Argentina. Universidad de Buenos Aires (UBA). Facultad de Agronomía; Argentina.Fil: Behrends Kraemer, Filipe B. Instituto Nacional de Tecnología Agropecuaria (INTA); Argentina.Fil: Garibaldi, Lucas Alejandro. Universidad de Buenos Aires (UBA). Facultad de Agronomía; Argentina.Bacterial retention by soils is a key factor in predicting bacterial transport through surface runoff into water bodies. The objective was to evaluate biological, soil and hydrologic factors that affect bacterial retention in three soil types of the Rolling Pampa, Argentina. Simulated rainfall was applied on field plots previously inoculated with Escherichia coli and simultaneously biological variables such as bacterial adsorption and distribution coefficient were measured at laboratory. Soil variables, particularly pH, exchangeable sodium percentage and organic carbon as well as biological variables proved to be important properties in the regulation of bacterial retention processes. There were no significant differences between the biological variables measured in soils and in the sediments. Most of the microorganisms in the runoff from all sites were either free of (in the < 2 μm sediment fraction) or associated with small soil particles (2 to 50 μm), therefore management practices, such as filter strips, should be regarded with caution when implemented

Potential Vulnerability of Natural Populations of Camu-camu (Myrciaria dubia) to Anthropogenic Stressors in Southwestern Amazon.

O camu-camu (Myrciaria dubia) é uma espécie amazônica economicamente promissora, cujos frutos possuem o maior teor de vitamina C já registrado, com alto potencial para aplicações na indústria de alimentos, suplementos e cosméticos, podendo ser a cultura principal em iniciativas agroflorestais de produtores locais. O camu-camu tem ampla distribuição na Amazônia, embora a maioria dos estudos e coletas tenham ocorrido na Amazônia Central e Ocidental. Este estudo tem como objetivo avaliar a distribuição e a vulnerabilidade das populações de camu-camu no estado de Rondônia, Brasil. Sua distribuição no limite sul apresenta áreas com um clima mais seco. Foram utilizados dados registrados em herbários e de expedições de bioprospecção, ademais, dados sobre perturbações antrópicas como incêndios, desmatamento e barragens (planejadas e existentes) estratificadas a nível municipal. Os registros de Camu-camu ocorreram preferencialmente nas regiões norte e central do estado, porém a maior parte das coletas ocorreu no entorno das cidades, grandes rios e estradas, mostrando um forte viés do coletor. Nos municípios com ocorrência de camu-camu foram observadas maiores taxas de desmatamento, incêndios e barragens, quando comparados aos municípios sem registros. As populações de camu-camu em Rondônia habitam condições mais secas e podem estar mais adaptadas às futuras condições geradas pelas mudanças climáticas na Amazônia. Estas adaptações podem ser úteis para os futuros esforços de melhoramento genético da espécie. Dessa forma, é necessário um maior esforço para manutenção da biodiversidade de populações de camu-camu em paisagens dominadas pelo homem, além de incentivar a conservação ex situ em áreas produtivas de agricultores locais, especialmente sob a perspectiva das mudanças climáticas globais

Enxertia em figueira Roxo de Valinhos por borbulhia e garfagem.

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