Management of soil organic matter in small-scale farmers cropping systems: possibilities and limitations.

Editado por Reinhard Lieberei, Helmut Bianchi, Vera Boehm, Christoph Reisdorff. Publicado também em GERMAN-BRAZILIAN WORKSHOP ON NEOTROPICAL ECOSYSTEMS: ARCHIEMENTS AND PROPECTS OF COOPERATIVE RESEARCH, 2000, Hamburg. Program and abstracts. Hamburg: SHIFT: MADAM: WAVES, 2000. p. 102

Cultivo do milho em sistema de corte e trituração da capoeira na região Nordeste do Pará efeito da época do preparo de área.

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Identifying chemokines as therapeutic targets in renal disease: Lessons from antagonist studies and knockout mice

Chemokines, in concert with cytokines and adhesion molecules, play multiple roles in local and systemic immune responses. In the kidney, the temporal and spatial expression of chemokines correlates with local renal damage and accumulation of chemokine receptor-bearing leukocytes. Chemokines play important roles in leukocyte trafficking and blocking chemokines can effectively reduce renal leukocyte recruitment and subsequent renal damage. However, recent data indicate that blocking chemokine or chemokine receptor activity in renal disease may also exacerbate renal inflammation under certain conditions. An increasing amount of data indicates additional roles of chemokines in the regulation of innate and adaptive immune responses, which may adversively affect the outcome of interventional studies. This review summarizes available in vivo studies on the blockade of chemokines and chemokine receptors in kidney diseases, with a special focus on the therapeutic potential of anti-chemokine strategies, including potential side effects, in renal disease. Copyright (C) 2004 S. Karger AG, Basel

Land-use in a mulch-based farming system of small holders in the eastern Amazon.

Burning is a commonly used method to clear land for cropping, especially in regions with shifting cultivation. Due to population growth with the resulting intensified land use, it is mostly combined with a shortening of the fallow periods. Both burning and the shortened fallow period are the principal causes of declining soil fertility, and they are symptomatic for Eastern Amazonian agriculture. Based on the assumption that shifting cultivation will be maintained as the basic land-use system, these two adverse factors have to be improved in order to achieve reasonable and increased sustainable productivity. In the framework of a bilateral German-Brazilian research project, mechanized mulching technologies were developed to carry out fire-free land clearing by cutting and chopping the tree-rich fallow vegetation creating a mulch layer. Besides preserving organic matter and mineral nutrients, mulching permits land preparation at any time of the year, as, in contrast to burning, it does not depend on the dry season. Enriching the fallow vegetation with fast growing trees enhances the effect of mulching by increasing biomass: 25 t/ha/year as compared to natural fallow with 10 t/ha/year during the linear growth phase in the first 2 - 3 years. When putting these technologies into practice, the demand on differently behaving nutrient stocks in mulch-based systems has to be met. On the other hand, fire-free land preparation allows for flexible, alternative land utilization practices. Both factors lead to new crop-fallow scenarios where land use is intensified whilst the basic principles of shifting cultivation are maintained. In particular: 1) fallow biomass increase by enrichment reduces the fallow period from 4 - 6 years to 2 years, 2) slow nutrient release from the mulch layer allows highly demanding crops to be planted at the end of the cropping period low mineral fertilizer input is desired, 3) an additional cropping period becomes possible and reduces the land preparation time by half, 4) independent of the dry season crops can be planted taking climate and market demands into consideration, and 5) perennial cash crops can be integrated into the crop rotation

Mechanized land preparation in forest-based fallow systems: the experience from eastern Amazonia.

The slash-and-burn practice of land preparation that farmers use traditionally in forest-based fallow systems in the humid tropics causes land degradation and human health hazards. As an alternative to slash-and-burn, a mechanized, fire-free method of land preparation was evaluated on smallholdings in the eastern Amazon region. The use of machinery for harvesting fallow vegetation and chopping it for mulch eliminates the need for hard labor and fire for land clearing and increases labor productivity. Four different tractor-propelled choppers with power demand of 50 kW to 122 kW were tested. Their chopping capacity varied between 4.5 Mg and 20 Mg of fresh biomass per hour. The mechanized chop-and-mulch technology can be used in fallow vegetation that is up to 12 years old, which in the study region corresponded to 20 Mg to 150 Mg fresh biomass per hectare. Two additional choppers ? a stationary silage chopper and a high-powered crawler tractor with a chopping device ? were also tested but both were not suitable for smallholder fallow systems. In the context of the mulch technology, new low-input crop varieties were screened and their response to fertilizer was studied. The mulch technology facilitates extended cropping, to plant crops off-season, and modify crop rotation. Degraded fallow vegetation can be improved by enrichment planting using fast-growing leguminous tree species. Financial analysis of different scenarios revealed that farm income and labor productivity from chop-and-mulch systems can be up to two times greater than from the traditional slash-and-burn system

5d-4f luminescence of Ce3, Gd3 and Lu3 in LiCaAlF6

The emission and excitation spectra as well as decay kinetics of luminescence due to 5d4f transitions in Ce3, Gd3 and Lu3 ions doped into LiCaAlF6 crystals have been analyzed with high spectral and time resolution using synchrotron radiation for excitation. The rich fine structure originating from electronic origins of transitions and their phonon replica has been well resolved and identified. Experimental data are compared with the spectra simulated in the framework of the semiphenomenological models of the crystal field and the crystal lattice dynamics. © 2011 Elsevier B.V. All rights reserved