Biomassa microbiana em solo manejado com e sem queima de resíduos orgânicos.

O uso do fogo, embora necessário em algumas atividades, é uma prática condenável, uma vez que causa impactos ambientais negativos. O carbono da biomassa microbiana é um indicador sensível às mudanças determinadas pelo manejo do solo, como o uso do fogo. Para avaliar as alterações ocorridas na biomassa microbiana do solo no decorrer dos cultivos, foram conduzidos dois experimentos: I -Com queima dos resíduos orgânicos, e II - sem queima dos resíduos orgânicos. Os tratamentos foram compostos por quatro doses de resíduos orgânicos (O, 15, 30 e 45 Mg ha-I); dois tipos de adubação (adubação exclusiva com resíduos de poda e adubação com resíduos .de poda acrescida da adubação mineral da cultura) e seis épocas de amostragem de solo (floração e colheita de duas safras de milho e uma safra de feijão). Para cada época foi avaliado o conteúdo de carbono da biomassa microbiana do solo da camada de 0-10 cm. Os resultados permitiram concluir que o carbono da biomassa microbiana diminuiu quando se empregou a queima dos resíduos e aumentou com as doses de resíduo, independentemente do tipo de adubação utilizada, nos experimentos com e sem queima de resíduos

Dados climatológicos: estação de Paraipaba, 2003.

bitstream/CNPAT-2010/12035/1/Dc-084.pd

Orbit determination of Transneptunian objects and Centaurs for the prediction of stellar occultations

The prediction of stellar occultations by Transneptunian objects and Centaurs is a difficult challenge that requires accuracy both in the occulted star position as for the object ephemeris. Until now, the most used method of prediction involving tens of TNOs/Centaurs was to consider a constant offset for the right ascension and for the declination with respect to a reference ephemeris. This offset is determined as the difference between the most recent observations of the TNO and the reference ephemeris. This method can be successfully applied when the offset remains constant with time. This paper presents an alternative method of prediction based on a new accurate orbit determination procedure, which uses all the available positions of the TNO from the Minor Planet Center database plus sets of new astrometric positions from unpublished observations. The orbit determination is performed through a numerical integration procedure (NIMA), in which we develop a specific weighting scheme. The NIMA method was applied for 51 selected TNOs/Centaurs. For this purpose, we have performed about 2900 new observations during 2007-2014. Using NIMA, we succeed in predicting the stellar occultations of 10 TNOs and 3 Centaurs between 2013 and 2015. By comparing the NIMA and JPL ephemerides, we highlighted the variation of the offset between them with time. Giving examples, we show that the constant offset method could not accurately predict 6 out of the 13 observed positive occultations successfully predicted by NIMA. The results indicate that NIMA is capable of efficiently refine the orbits of these bodies. Finally, we show that the astrometric positions given by positive occultations can help to further refine the orbit of the TNO and consequently the future predictions. We also provide the unpublished observations of the 51 selected TNOs and their ephemeris in a usable format by the SPICE library.Comment: 12 pages, 9 figures, accepted in A&

Rhizobial diversity from stem and root nodules of Discolobiumand Aeschynomene.

Among the genera that exhibit stem nodulation, Aeschynomeneand Discolobiumare found in the Pantanal Mato-grossense (wetlands in the state ofMato Grosso, Brazil). Isolates obtained from the stem and root nodules of D. pulchellum, D. psoraleaefolium, D. leptophyllumand A. fluminensiswere collected from various locations in the Pantanal de Poconésub-region and phenotypically characterized and genotyped by restriction analysis of the 16S rDNA gene. Of the 282 isolates obtained from the stem and root nodules, 84.3% alkalized YMA media and 74.1% showed slow growth. No differences in either the phenotype or the genotype among the rhizobial populations isolated from the root or stem nodules of the species Discolobiumand A. fluminensis were observed. Among the isolates obtained from D. pulchellum,there was a group that was not similar to any of the reference strains used, and most of the isolates analyzed by PCR-RFLP were similar to the genus Bradyrhizobium