Transformações do nitrogênio em solos tratados com lodo de esgoto.

O uso de lodo de esgoto ou biossólido na agricultura é uma prática bem conhecida em todo o mundo, principalmente na Europa e Estados Unidos. No Brasil, os estudos sobre o uso de lodo de esgoto como fonte de matéria orgânica e nutrientes ainda são escassos e limitados. Portanto, o objetivo deste estudo foi avaliar a mineralização do nitrogênio e do pH do solo e da variação da condutividade elétrica após a aplicação do lodo de esgoto de Franca e Barueri, ETE - Franca e ETE - Barueri, respectivamente, em solos arenosos e argilosos. Os menores valores de pH foram observados com a aplicação de lodo de esgoto da ETE - Franca no solo argiloso tratado com a dose mais elevada. Os valores de condutividade elétrica em ambos os solos aumentou após adição dos dois tipos de lodo e variou 0,18-1,85 dS m-1 na dose mais baixa e mais alta, respectivamente. Maiores concentrações de N-NH4 + foram observados nos solos que foram tratados com lodo de esgoto da ETE - Franca, e chegou a 513 mg kg-1 de solo. Os N- NO3 - concentrações foram maiores nos solos tratados com lodo da ETE - Barueri, e atingiu cerca de 800 mg kg-1 de solo, independentemente do tipo de solo

Induced and Spontaneous Technology-Based Companies in the Metropolitan Region of Campinas: limitations, potentialities and relations with the geographic space

The objective of this paper is to analyze a set of technology-based enterprises connected to incubators and the University of Campinas, both located in the Metropolitan Region of Campinas, Brazil. We call these, respectively, “induced” and “spontaneous” companies. A survey was conducted directly with the companies and reveled an answer rate of 31% for our population connected to incubators and 24% for those connected with the university. We propose a discussion of firm’s endogenous and exogenous characteristics, as well as their relations with the geographic space. Our main conclusions are as follows: 1) the space emerges as fundamental in the creation and development of technology-based endeavors, 2) both groups of companies do not differ substantially in successful growth potential, 3) differences emerge with the level of integration with the university and network access, and 4) their main limitation is connected with financing access.Regional and urban economics; New economic geography; Technology-based enterprises; Metropolitan Region of Campinas; Technopolis

Clonagem de genes ureG putativos de Glomus intraradices e atividades de urease em raízes micorrízicas arbusculares de tabaco

Even though the major benefit of arbuscular mycorrhizae is the increased uptake of phosphate from the soil solution and translocation to the plant, changes in the activity of enzymes involved in nitrogen (N) metabolism have been detected in mycorrhizal roots. Using differential display of reverse-transcripts of tobacco roots not-inoculated or inoculated with Glomus intraradices (Gi), we have cloned two partial cDNAs (NtGi2 and NtGi3). The presence of a conserved CobW/HypB/UreG domain and phylogenetic analyses suggest that NtGi2 and NtGi3 encode isoforms of urease accessory protein G (ureG) highly similar to ureG from fungi. The steady state levels of the putative ureG transcripts were shown to be higher in roots colonized by Gi, as compared to non-mycorrhizal controls. Urease activities were also determined in tobacco roots inoculated with Glomus clarum (Gc) or Gi and grown in substrate containing 50, 100 or 150 mg N kg-1 in the form of ammonium sulfate (N-AMS) or urea (N-URE). Urease activities were shown to be induced in mycorrhizal roots fertilized with 100 mg N-AMS kg-1. In Gc-colonized roots fertilized with N-URE, induction of urease activities was observed at the lowest N concentration. In contrast, at the highest N-URE concentration, suppression of urease activities was observed in Gc and Gi-colonized roots, as compared to non-mycorrhizal controls. Urease activities in roots were modulated by soil N availability and source, and arbuscular mycorrhizal fungal inoculation.Muito embora o maior benefício de micorrizas arbusculares seja o incremento na absorção de fosfato da solução do solo e translocação para a planta, alterações nas atividades de enzimas envolvidas no metabolismo de nitrogênio (N) têm sido detectadas em raízes micorrizadas. Usando differential display of reverse-transcripts de raízes de tabaco não-inoculadas ou inoculadas com Glomus intraradices (Gi), dois cDNAs parciais (NtGi2 e NtGi3) foram clonados. A presença de um domínio CobW/HypB/UreG conservado e a análise filogenética sugerem que NtGi2 e NtGi3 codificam isoformas de proteínas acessórias da urease G (ureG) altamente similares a ureG de fungos. Os níveis de transcritos dos genes ureG putativos foram mais elevados em raízes colonizadas por Gi, em relação ao controle não-micorrizado. As atividades de urease foram determinadas em raízes de tabaco inoculadas com Glomus clarum (Gc) ou Gi e cultivadas em substrato contendo 50, 100 ou 150 mg N kg-¹, na forma de sulfato de amônio (N-AMS) ou uréia (N-URE). As atividades de ureases foram induzidas em raízes micorrizadas cultivadas com 100 mg N-AMS kg-¹. Em raízes colonizadas por Gc e cultivadas com N-URE, a indução das atividades de urease foi observada na concentração mais baixa de N. Em contraste, na concentração mais elevada de N-URE, supressão das atividades de urease em raízes colonizadas por Gc e Gi, em relação aos controles não-micorrizados, foi observada. As atividades de urease nas raízes foram moduladas pela disponibilidade e fonte de N no solo, e pela inoculação com fungos micorrízicos arbusculares.FAPESPCNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

Water uptake in deep soil layers by tropical eucalypt plantations: consequences for water resources under climate change. [P117]

Climate models predict that the frequency, intensity and duration of drought events will increase in tropical regions. Questions such as how planted forests will adapt to future constraints on water availability have broad implications for the supply of wood at low cost that contributes to decreasing the pressure on native forests. Although water uptake by deep roots is generally considered as an efficient adaptation to drought in tropical planted forests, the role of very deep roots to supply the water requirements of trees is still poorly known. Fine roots have been observed in Eucalyptus plantation down to a depth of 16m 5 years after planting in Brazil. The contribution of water stored in deep soil layers to stand evapotranspiration has been quantified using a process-based model over 5 years after planting. Daily simulations of latent heat fluxes and soil water contents down to a depth of 10m satisfactorily matched with measurements over the study period. Our results show that deep roots play a major role in supplying tree water requirements during extended dry periods in Eucalyptus plantations. The fast exploration of deep soil layers by roots provides access to large amounts of water stored in the soil after clear cutting. The water table is no more recharged after canopy closure and the primary production is highly dependent on rainfall amounts as well as on the ability of trees to withdraw water in the water table. Water uptake by tree roots progressed towards deep soil layers during dry periods. On average 20% of tree transpiration was withdrawn below a depth of 10m during the dry seasons. The withdrawal of water in the water table, between the depths of 12 and 18m, occurred during dry periods from age 2 years onwards. Although the amounts of water withdrawn in the water table were small (~1-3% of total transpiration over the study period), this process can be of paramount importance for tree survival in tropical regions in a context of climate changes. (Texte intégral

Land Reform, Efficiency and Rural Institutional Change: theory and stochastic frontier analysis with panel data (1998-2006)

This work deals with land reform in Brazil through an evolutionary and new institutional economics theoretical framework. Firstly, this theoretical underpinning delineates the existence of an intrinsic relation between asset equality and economic efficiency, going against the neoclassical trade-off. From this relation it is established that the utilization of society’s productive forces depends directly on institutional structures and propriety relations. In this sense, the way land reallocations are done, through different land redistribution policies, affects directly the level of agricultural product. The product is dependent on the level of allocative and technical efficiency society is submitted to. However, albeit static effects, society is susceptible to dynamic effects of institutional change. Insofar we develop analytical schematics where land reform is related to rural institutional change. From this schematics we derive the hypothesis that the market based land reform executed in Brazil, as a way to redistribute assets supposedly with a governance structure, system of incentives and complementary institutions to the factor markets, there is a gain in systemic productive efficiency at the microeconomic level. To test this hypothesis we develop a stochastic frontier econometric model with time-varying technical inefficiency effects and panel data. We analyze 106 projects of the Cédula da Terra Program in the states of Bahia, Maranhão, North of Minas Gerais, Pernambuco and Ceará, for the years 2000 and 2006. We conclude that this land reform has partial success in establishing productive organizations that evolve constantly their efficiency, wherein learning-by-doing is fundamental. Additionally, the governance effects are limited – the structure was not devised for institutional change – effects of transaction costs and conventions remain, causing market failure and persistence of inefficient forms of organization.land reform, cédula da terra, brazil, stochastic frontier analysis, evolutionary, institutional economics

Water withdrawal from deep soil layers: a key strategy to sustain growth during dry seasons in tropical Eucalyptus plantations

Little is known about the role of very deep roots to supply the water requirements of tropical forests. Clonal Eucalyptus plantations managed in short rotation on very deep Ferralsols are simple forest ecosystems (only 1 plant genotype growing on a relatively homogeneous soil) likely to provide an insight into tree water use strategies in tropical forests. Fine roots have been observed down to a depth of 6 m at age 1 year in Brazilian eucalypt plantations. However, the contribution of water stored in very deep soil layers to stand evapotranspiration over tree growth has been poorly quantified. An eco-physiological model, MAESPA, has been used to simulate half-hourly stand water balance over the first three years of growth in a clonal Eucalyptus grandis plantation in southern Brazil (Eucflux project, State of São Paulo). The water balance model in MAESPA is an equilibrium-type model between soil and leaf water potentials for individual trees aboveground, and at the stand scale belowground. The dynamics of the vertical fine root distribution have been taken into account empirically from linear interpolations between successive measurements. The simulations were compared to time series of soil water contents measured every meter down to 10m deep and to daily latent heat fluxes measured by eddy covariance. Simulations of volumetric soil water contents matched satisfactorily with measurements (RMSE = 0.01) over the three-year period. Good agreement was also observed between simulated and measured latent heat fluxes. In the rainy season, more than 75 % of tree transpiration was supplied by water withdrawn in the upper 1 m of soil, but water uptake progressed to deeper soil layers during dry periods, down to a depth of 6 m, 12 m and 15 m the first, second and third year after planting, respectively. During the second growing season, 15% of water was withdrawn below a depth of 6 m, and 5% below 10m. Most of the soil down to 12m deep was dried out the second year after planting and deep drainage was negligible after 2 years. As a consequence, during the third year after planting only 4% of water was taken up below 6m. However, during the dry season, this deep water still supplied 50% of water requirements. Our results show that deep fine roots of E. grandis play a major role in supplying tree water requirements during extended dry periods. Large amounts of water are stored in the whole soil profile after clear cutting and the fast exploration of deep soil layers by roots make it available for tree growth. After canopy closure, precipitation becomes the key limitation for the productivity of these plantations grown in deep sandy soils. Our results suggest that a territorial strategy leading to a fast exploration of very deep soil layers might provide a strong competitive advantage in regions prone to drought

Development without deforestation

The conservation projects managed by the United Nations Development Programme (UNDP) in Brazil are underpinned by a strong element of inclusive local development, consisting of innovative initiatives regarding the sustainable use of biodiversity. There are many examples of projects in Mangrove, Caatinga and Cerrado areas, which conciliate the production of goods and environmental services with the generation of jobs, income and an increase in life quality. It is always an enormous challenge to assure opportunities to the most vulnerable populations living in areas characterised by a great expansion of agricultural commodities production and cattle ranching, while respecting people's livelihoods and protecting the environment. [...

Desenredando os mecanismo de sinalização e transdução de sinais que controlam o desenvolvimento de micorrizas arbusculares

Arbuscular mycorrhiza (AM) are the most widespread symbiotic associations between plant roots and soil fungi. AM can contribute to increasing the survival and fitness of plants to limiting environments mostly due to their ability in improving nutrient uptake from the soil solution. Despite their ecological significance, the mechanisms controlling AM development and functioning are largely unknown. The obligate mutualistic nature of the arbuscular mycorrhizal fungi (AMF) has hampered the advances on the understanding and application of the symbiosis. Significant alterations in the genetic programs of both symbionts are required for the successful establishment of an AM, and complex signaling and signal transduction mechanisms are likely involved. The analyses of legume mutants affected in the development of nitrogen fixing nodules and AM suggest that part of the signal transduction pathways involved in the regulation of both symbioses are conserved. Even though the use of genomics of model plants has helped to advance our understanding of the regulatory mechanisms in AM, identifying the signal molecules involved in plant-AMF communication and determining their transduction pathways is still essential for its biotechnological application in agriculture.As micorrizas arbusculares (MAs) são as associações simbióticas entre raízes de plantas e fungos mais comuns na natureza. Elas podem contribuir para o aumento da sobrevivência e adaptação das plantas a ambientes limitantes, principalmente devido a sua maior capacidade em absorver nutrientes da solução do solo. Apesar de sua importância ecológica, os mecanismos que controlam o desenvolvimento e fisiologia das MAs são pouco conhecidos. A natureza mutualística obrigatória dos fungos micorrízicos arbusculares (FMAs) tem limitado os avanços na compreensão e aplicação da simbiose. Alterações significativas nos programas genéticos de ambos simbiontes são necessárias para o estabelecimento de MAs, e mecanismos complexos de sinalização e transdução de sinais estão provavelmente envolvidos. A análise de mutantes de leguminosas defectivos no desenvolvimento de nódulos fixadores de nitrogênio e MAs sugere que uma parte das vias de transdução de sinais envolvidas na regulação dessas simbioses é conservada. Muito embora o uso da genômica de plantas modelos tenha contribuído para o avanço na compreensão dos mecanismos que regulam MAs, a identificação de moléculas sinais envolvidas na comunicação planta-FMA, e a determinação de suas vias de transdução, é essencial para aplicação da simbiose na agricultura

Judicial subversion: The effects of political power on court outcomes

Are politicians in power treated more leniently in court? We show that Brazilian mayoral candidates charged with misconduct are 65 percent less likely to be convicted if they narrowly win the election. Politicians play no direct role in the judges’ careers, suggesting that formal independence does not completely insulate the judiciary from political influence. The effect is driven by districts with few judges and by judges with higher career instabilityinfo:eu-repo/semantics/publishedVersio

Judicial subversion: The effects of political power on court outcomes

Are politicians in power treated more leniently in court? We show that Brazilian mayoral candidates charged with misconduct are 65 percent less likely to be convicted if they narrowly win the election. Politicians play no direct role in the judges’ careers, suggesting that formal independence does not completely insulate the judiciary from political influence. The effect is driven by districts with few judges and by judges with higher career instability.publishedVersio