Biological Fixation of N2 in Mono and Polyspecific Legume Pasture in the Humid Mediterranean Zone of Chile

del Pozo, A (del Pozo, Alejandro). Univ Talca, Fac Ciencias Agr, Talca, ChileDespite annual legume pasture are of great importance for dryland agricultural systems in Mediterranean environments, there are few studies of N-2 biological fixation (NBF) reported in Chile. In this study the NBF of four annual legume species: subterranean clover (Trifolium subterraneum L.), yellow serradella (Ornithopus compressus L.), arrow-leaf clover (T. vesiculosum L.), and crimson clover (T. incarnatum L.) (Experiment 1), as well as seven mixtures of these species (Experiment 2) were assessed. The NBF was measured by the N-15 natural abundance technique. The objective was to determine NBF in the legume species and in distinct mixtures used. The study was carried out in an Andisol of the Andean Precordillera located in the humid Mediterranean zone of Chile. Pasture was evaluated for biomass; and total N and natural abundance of N-15 were analyzed in plant material samples. In Experiment 1 (monospecific legume species pasture), N derived from fixation ranged between 43 and 147 kg N ha(-1) and where T. vesiculosum and T. subterraneum presented statistical differences (P <= 0.05) in connection with the other species. In the legume mixtures (Experiment 2), N derived by fixation varied between 97 and 214 kg N ha(-1) where the 50-50 mixtures (T. subterraneum and O. compressus, or T. subterraneum and T. vesiculosum, respectively) had the highest N fixation. Fixed N ranged between 12 and 25 kg N t(-1) DM, showing significant differences among mono and polyspecific legume species

Bactérias promotoras de crescimento e adubação nitrogenada no crescimento inicial de cana-de-açúcar proveniente de mudas pré-brotadas

O objetivo deste trabalho foi avaliar os efeitos da inoculação de bactérias promotoras de crescimento sobre a formação de mudas pré?brotadas de cana?de?açúcar, oriundas de gemas individualizadas, e quantificar o crescimento inicial dessas mudas, em associação à aplicação de nitrogênio, em solo de baixa fertilidade. Foram conduzidos dois experimentos: um em casa de vegetação, com duração de 50 dias, e o outro, em vasos no campo, com duração de 180 dias. Em ambos os experimentos, utilizou-se o delineamento de blocos ao acaso, em arranjo fatorial 2x3, no primeiro experimento ? com ou sem inoculante, e com três quantidades de reserva nas gemas ?, e 2x2x4, no segundo ? com ou sem inoculante, com ou sem nitrogênio, avaliados em quatro épocas: aos 45, 90, 135 e 180 dias. O inoculante produziu efeito na fase inicial de crescimento das mudas pré?brotadas, com aumento na velocidade de brotação e no acúmulo da matéria seca de raízes e da parte aérea, independentemente da quantidade de reserva da gema. No segundo experimento, o inoculante promoveu ganhos no crescimento inicial da parte aérea e do sistema radicular, até os 180 dias após o transplantio, com aumento em altura, perfilhamento, diâmetro do colmo, produção da matéria seca de colmos e de palha e do comprimento radicular, independentemente da aplicação de nitrogênio. O inoculante tem efeito fisiológico positivo sobre o crescimento das plantas

Recuperação no sistema solo-planta de nitrogênio derivado da adubação verde aplicada à cultura do repolho.

O objetivo deste trabalho foi determinar a eficiência de recuperação, no sistema solo-planta, do nitrogênio derivado da adubação verde aplicada à cultura de repolho (Brassica oleracea). O experimento foi dividido em duas etapas: a primeira consistiu da produção de palhada de feijão-de-porco (Canavalia ensiformis), mucuna-cinza (Mucuna cinereum), e sorgo (Sorghum bicolor), em substrato enriquecido com 15N. A segunda etapa consistiu da aplicação das palhadas marcadas com 15N, em cobertura nos canteiros com repolho. Os tratamentos consistiram de: palha fresca de feijão-de-porco; palha fresca de mucuna-cinza; palha fresca de sorgo; mistura das palhas de mucuna, feijão-de-porco e sorgo a 1:1:1; e controle sem adubação verde. A recuperação de N no sistema solo-planta foi influenciada pelo tipo de palhada utilizado, e a eficiência de recuperação do N derivado da palhada de leguminosa variou de 9 a 16%. O tratamento com palha de feijão-de-porco é o que apresenta maior eficiência de recuperação e, portanto, a melhor sincronia da oferta de nitrogênio pela decomposição da palhada com a demanda pela cultura do repolho

Efeito estufa e o seqüestro de carbono em sistemas de cultivo com espécies florestais e na cultura de cana-de-açúcar.

Efeito estufa. Interferência e previsões sobre o efeito estufa. O protocolo de Kyoto e o mecanismo de desenvolvimento limpo. Sequestro de carbono em ecossistemas terrestres. O caso do eucalipto. O caso do dendê. O caso da cana-de-açúcar. Importância da FBN para o sequestro de carbono. Estimativas do sequestro de C na cultura de cana-de-açúcar. O Brasil e as emissões de gases do efeito estufa.bitstream/CNPAB-2010/27401/1/doc133.pd

Efeito do nitrogênio na população de metanogênicas e emissões de metano, em diferentes cultivares de arroz irrigado.

O nitrogênio e a cultivar de arroz podem aumentar os fluxos de metano (CH4). Este trabalho avaliou a população de metanogênicas (gene mcrA), em função da adubação com N, sob cultivo de diferentes cultivares de arroz. Foram instalados dois experimentos, em blocos ao acaso, com parcelas subdivididas e quatro repetições. O primeiro, em Pindamonhangaba-SP, entre janeiro a julho/2015, utilizou as cultivares IAC-105 (135 dias) e Epagri-106 (< 120 dias) como tratamentos, com duas amostragens (solo e gás) no tempo, antes e 24h após a adubação com N em cobertura (100 kg ha-1). O segundo, em Arari-MA, de setembro/2015 a janeiro/2016, diferenciou-se nas cultivares: BRS-357 (140 dias), PUITÁ e IRGA-429 (90 a 110 dias). Os fluxos de CH4, coletados em câmaras estáticas fechadas, ajustáveis à altura das plantas, foram quantificados por cromatografia gasosa usando detector FID, calculados segundo Rolston. Foram amostrados cerca de 200g de solo rizosférico (0-10cm) e 5g foi armazenado à -70ºC, para a quantificação do nº de cópias do gene mcrA, por Real-Time PCR (qPCR). O restante foi usado nas análises de nitrato (NO3 - ), amônio (NH4+) e carbono solúvel (C). O teste T revelou que, em Pindamonhangaba-SP, houve aumento significativo nos teores de C e NH4 + no solo, após a adubação, que pode ter resultado no aumento do número de cópias do gene mcrA, com tendência de aumento na emissão de CH4. Em Arari-MA, o aumento dos teores de NH4 + após a adubação foi acompanhado de maiores emissões, mas sem efeito significativo. Porém, elas quase dobraram na cultivar IRGA-429 (46 a 70 mg de CH4 ha-1 dia-1) ou triplicaram na cultivar BRS-357 (7,8 a 25 mg de CH4 ha-1 dia-1). O nº de cópias de mcrA, em Arari, estavam abaixo do limite de detecção por qPCR, principalmente, antes da adubação. È possível que as metanogênicas tenham se distribuído por zonas mais anaeróbicas do que a rizosfera. Não houve efeito de cultivar nas variáveis analisadas, mas a adição de N tende a aumentar as emissões, seja pela absorção de N pela planta, o que explicaria o aumento no teor de C no solo, via exsudados da raiz, ou por NH4 + e CH4 competirem pelos mesmos sítios enzimáticos de oxidação, em alguns microrganismos metano oxidantes

Impact of the intensification of beef production in Brazil on grenhouse gas emissions and land use.

Brazil has the largest herd of beef cattle in the world, estimated at approximately 200 million animals. Production is predominantly pasture-based and low input and hence time to slaughter is long, which promotes high methane (CH4) emissions per kg of product. The objective of this study was to investigate the impact of increasing animal productivity using fertilizers, forage legumes, supplements and concentrates, on the emissions of greenhouse gases (GHGs) in five scenarios for beef production in Brazil. A life cycle analysis (LCA) approach, from birth of calves to mature animals ready for slaughter at the farm gate, was utilized using Tier 2 methodologies of the IPCC and the results expressed in equivalents of carbon dioxide (CO2eq) per kg of carcass produced. Fossil CO2 emitted in the production of supplements, feeds and fertilizers was included using standard LCA techniques. The first four scenarios were based solely on cattle production on pasture, ranging from degraded Brachiaria pastures, through to a mixed legume/Brachiaria pasture and improved N-fertilized pastures of Guinea grass (Panicum maximum). Scenario 5 was the most intensive and was also based on an N-fertilized Guinea grass pasture, but with a 75-day finishing period in confinement with total mixed ration (TMR). Across the scenarios from 1 to 5 the increase in digestibility promoted a reduction in the forage intake per unit of animal weight gain and a concomitant reduction in CH4 emissions. For the estimation of nitrous oxide (N2O) emissions from animal excreta, emission factors from a study in the Cerrado region were utilized which postulated lower emission from dung than from urine and much lower emissions in the long dry season in this region. The greatest impact of intensification of the beef production systems was a 7-fold reduction of the area necessary for production from 320 to 45 m2/kg carcass. Carcass production increased from 43 to 65 Mg per herd across the scenarios from 1 to 5, and total emissions per kg carcass were estimated to be reduced from 58.3 to 29.4 kg CO2eq/kg carcass. Even though animal weight gain was lower in the mixed grass-legume scenario (3) than for the N-fertilized Guinea grass pastures (scenarios 4 and 5) GHG emissions per kg carcass were similar as the legume N2 fixation input had no fossil-fuel cost. A large source of uncertainty for the construction of such LCAs was the lack of data for enteric CH4 emissions from cattle grazing tropical forages

Medical Student Knowledge of Neglected Tropical Diseases in Peru: A Cross-Sectional Study

Abstract\ud \ud In developing countries, education to health-care professionals is a cornerstone in the battle against neglected tropical diseases (NTD). Studies evaluating the level of knowledge of medical students in clinical and socio-demographic aspects of NTD are lacking. Therefore, a cross-sectional study was conducted among students from a 7 year-curriculum medical school in Peru to assess their knowledge of NTD by using a pilot survey comprised by two blocks of 10 short questions. Block I consisted of socio-demographic and epidemiological questions whereas block II included clinical vignettes. Each correct answer had the value of 1 point. Out of 597 responders (response rate: 68.4%), 583 were considered to have valid surveys (male:female ratio: 1:1.01; mean age 21 years, SD ± 2.42). Total knowledge showed a raising trend through the 7-year curriculum. Clinical knowledge seemed to improve towards the end of medical school whereas socio-demographic and epidemiological concepts only showed progress the first 4 years of medical school, remaining static for the rest of the curricular years (p = 0.66). Higher mean scores in socio-demographic and epidemiological knowledge compared to clinical knowledge were seen in the first two years (p<0.001) whereas the last three years showed higher scores in clinical knowledge (p<0.001). In conclusion, students from this private medical school gained substantial knowledge in NTD throughout the career which seems to be related to improvement in clinical knowledge rather than to socio-demographic and epidemiological concepts. This study assures the feasibility of measuring the level of knowledge of NTD in medical students and stresses the importance of evaluating education on NTD as it may need more emphasis in epidemiological concepts, especially at developing countries such as Peru where many people are affected by these preventable and treatable diseases.\ud \ud Author Summary\ud \ud Since the promulgation of the United Nations Millennium Development Goals in 2000 and the posterior creation of the WHO’s Department of Control of Neglected Tropical Diseases five years later; encouraging progress in the diagnosis, treatment and prevention of these infectious diseases has been made. However, millions of people are still affected. Efforts to control NTD should come from different instances: from the high policy-decision makers to the young health-care and science professionals. Countries should consider to evaluate the quality of the medical training in order to develop and sustain efficient control programs of NTD, under the assumption that adequate education and knowledge from health-care providers are key starting points, especially in endemic areas. Having said that, universities—uniquely positioned to provide biomedical, epidemiological and clinical expertise- play an important role. Therefore, this study provides an initial approach in measuring NTD knowledge in medical students and should encourage the development of further surveys that may help to evaluate existing NTD education programs, especially because current global health problems could benefit from students’ awareness at early stages of medical training