Fertilization effects on soil P, K, Ca and Mg contents in a mixed tree cropping system in Central Amazonia.

The main objective was to study the fertilizer effects on P, K, Ca e Mg contents in mixed tree cropping system with Brazil nut (Bertholletia excelsa), cupuaçu (Theobroma grandiflorum), peach palm (Bactris gasipaes), annatto (Bixa orellana) and pueraria (Pueraria phaseoloides)

Nutrient and water dynamics in a multi-strata agroforestry system.

In the presentel project, the nutriente and water fluxes are studied ann used as indicators for the stability of the agroforestry systems. The effects of the trees on soil properties, water and nutrient dynamics highly differed between species. To evaluate the sustaninability on an agroforestry system it is important to stress the consideration of spatial variability in the studied parameters. This variability creates the possibility to develop agroforestry with a complementary use of water and nutriente resources. The cropping sysytem with the current management is not seen as viable solution for land use in Amazonia at the moment. However, the discovered features of single trees and the effects on crop production and sustainability so far described encourage futher efforts to improve multi-strata agroforestry as a land use system for the Amazon region

Water and nutrient fluxes as indicators for the sustainability of different land-use systems on the terra firme near Manaus - a project overview.

Comparision of the water and nutrient fluxes in different perennial land-se systems, either monocultures or mixed cropping systems, in order to determine the resource efficiency of perennial land-se systems. They were comparision of the monocultue systems with Theobroma grandiflorum (cupuacu) or Bactris gasipaes (pupunha), polyculture systems with cupuacu, pupunh, Bixa orellana (urucum) and Bertholletia excelsa (castanha-do-Para) and primary and secondary forest sites. In the first experimental year, the equipment was installed to measure raianfall, throughfall, stemflow and soil water fluxes. These data combined with measurements of nutrient concentrations inform about the element fluxes. for this purpose, laboratory facilities were implemented to analyze anions and cations in the different land-se systems. Additionally, the nutrient and organic matter content of the soils were studied. Firt results showed that the investigated tree species differ in their effect on the water distribution and nutrient accumulation within the different cropping systems

Dinâmica da acidez num latossolo amarelo em diferentes sistemas de uso da terra na Amazônia.

Desenvolvimento de sistemas de uso da terra na Amazonia, visando o estudo da dinamica da acidez no solo. A acidez mais alta foi no nivel de adubacao mais baixo (30%-N-calcario), com diminuicao grandativa ate ao ultimo nivel (100%). Na profundidade de 0cm-5cm o efeito do calcario e' limitado e, por isso, a acidez e' maior na adubacao com 30%-N-Cal. em relacao a adubacao com 30%. Os niveis de abubacao foram iguais entre si e diferentes dos niveis com 100%, os quais tambem foram iguais entre si. A maior acidez nos dois niveis com 30% e' atribuida ao nivel baixo de adubacao

Nitrogen management for perennial crops in Amazonia.

Nitrogen is a growth-limiting nutrient in many forest and agricultural ecosystems in temperate and tropical climates

Statistical properties of thermodynamically predicted RNA secondary structures in viral genomes

By performing a comprehensive study on 1832 segments of 1212 complete genomes of viruses, we show that in viral genomes the hairpin structures of thermodynamically predicted RNA secondary structures are more abundant than expected under a simple random null hypothesis. The detected hairpin structures of RNA secondary structures are present both in coding and in noncoding regions for the four groups of viruses categorized as dsDNA, dsRNA, ssDNA and ssRNA. For all groups hairpin structures of RNA secondary structures are detected more frequently than expected for a random null hypothesis in noncoding rather than in coding regions. However, potential RNA secondary structures are also present in coding regions of dsDNA group. In fact we detect evolutionary conserved RNA secondary structures in conserved coding and noncoding regions of a large set of complete genomes of dsDNA herpesviruses.Comment: 9 pages, 2 figure

situ assessment of microbial sulfate reduction in a petroleum-contaminated aquifer using push-pull tests and stable sulfur isotope analyses

Abstract Anaerobic microbial activities such as sulfate reduction are important for the degradation of Ž . petroleum hydrocarbons PHC in contaminated aquifers. The objective of this study was to evaluate the feasibility of single-well push-pull tests in combination with stable sulfur isotope analyses for the in situ quantification of microbial sulfate reduction. A series of push-pull tests Ž was performed in an existing monitoring well of a PHC-contaminated aquifer in Studen Switzer-. land . Sulfate transport behavior was evaluated in a first test. In three subsequent tests, we injected Ž . Ž y . anoxic test solutions up to 1000 l , which contained 0.5 mM bromide Br as conservative tracer Ž 2y . and 1 mM sulfate SO as reactant. Ž . PII: S 0 1 6 9 -7 7 2 2 0 1 0 0 1 2 8 -0 Schroth et al.r Journal of Contaminant Hydrology 51 2001 179-195 180 analyses proved useful for the in situ quantification of microbial sulfate reduction in a PHC-contaminated aquifer.

Nutrient requirements of Amazonian tree crops - consequences for agroforestry use and management.

We studied soil fertility and plant nutrition in multi-strata agroforestry systems with several perennial crop species at four fertilization levels to obtain information on growth-limiting nutrients and to develop optimum sampling schemes for foliar analysis for the different species: peach palm (pupunha), cupuaçu, Brazil nut (castanha-do-Pará), annatto (urucu) and the cover crop Pueraria phaseoloides