Impact of soil tillage and land use on soil organic carbon decline under Mediterranean conditions

Soils under Mediterranean climate conditions frequently have low to very low levels of soil organic matter (SOM), as a result of low biomass production under the predominantly rainfed conditions and the intensive tillage operations commonly practiced. In order to assess both short and long-term impacts of soil tillage and land use on soil organic carbon, two sets of experiments were performed. One consisted in the identification and soil analysis of 3 pairs of sites under different soil types and land use over 5 to 30 years; in the second experiment a long-term fallow area was repeatedly submitted to different types of soil tillage management (mouldboard plough + disc harrow; non-inversion tine cultivation; no-till) over 3 years. Soil texture, bulk density and SOM were analysed along the whole soil profile in the first experiment, whereas bulk density and SOM to a depth of 30 cm was measured before the first tillage operations and at the end of the observation period in the second experiment. The results clearly indicate that tillage based land use, irrespective of the type of land use, caused a considerable decline in SOM content in the tilled soil layer. Very small and inconsistent differences in SOM between paired soil profiles were observed in the lower part of the profiles. In the second experiment with three types of tillage systems, SOM content decreased with tillage intensity. Avoidance of soil disturbance is an important step towards halting SOM decline under Mediterranean climate conditions

Próteses dentárias removíveis flexíveis: revisão narrativa de literatura

Apesar da popularidade crescente associada às próteses removíveis flexíveis existe um conhecimento limitado sobre o seu desempenho clínico. O objetivo deste trabalho baseia-se numa análise detalhada sobre as características funcionais e estéticas deste material. Foi realizada uma pesquisa bibliográfica de artigos científicos publicados entre 2003 e 2016, com recurso às bases de dados PubMed, ScienceDirect e Google Scholar, usando as palavras-chave “dental prosthesis”, “flexible denture”, “removable partial denture”. Foi dada preferência a estudos publicados na língua inglesa. Os estudos indicam que a resina de poliamida é uma alternativa às resinas acrílicas convencionais devido às suas características estéticas e funcionais. No entanto, apresentam algumas limitações como propriedades mecânicas inferiores em comparação com as convencionais. Estes dados sugerem que as próteses removíveis flexíveis, produzidas a partir de poliamida vieram trazer algumas melhorias na reabilitação oral.Despite the increasing popularity associated with flexible removable prosthesis there is limited knowledge about their clinical performance. The objective of this work is based on a detailed analysis on the functional and aesthetic characteristics of this material. A bibliographic search of scientific articles published between 2003 and 2016 was carried out, using the databases PubMed, ScienceDirect and Google Scholar, using the keywords "dental prosthesis", "flexible denture" and "removable partial denture". It was given preference to studies in the English language. Studies indicate that polyamide resin is an alternative to conventional acrylic resins because of its aesthetic and functional characteristics. However, they present some limitations as lower mechanical properties compared to conventional ones. These data suggest that flexible removable prosthesis made from polyamide have brought some improvement in oral rehabilitation

Control of weeds in wheat under no-till using reduced herbicide doses and application volumes

O objectivo do presente trabalho foi o de avaliar o efeito de doses reduzidas em relação ao recomendado pelo fabricante do herbicida diclofope-metilo + fenoxaprope – p – etilo + mefenepir dietilo e do volume de calda aplicado, no controlo em pós-emergência das infestantes gramíneas Avena sterilis L e Lolium rigidum G. em trigo de sementeira directa e o consequente efeito na produção da cultura. Assim, combinaram-se doses de herbicida inferiores às recomendadas (1; 1.5 e 2 l ha-1) com volumes de água também inferiores (100; 200 e 300 l ha-1) em dois estádios de desenvolvimento das infestantes (início do CONTROLO DE INFESTANTES EM TRIGO DE SEMENTEIRA DIRECTA UTILIZANDO DOSES DE HERBICIDA E VOLUMES DE CALDA REDUZIDOS CONTROL OF WEEDS IN WHEAT UNDER NO-TILL USING REDUCED HERBICIDE DOSES AND APPLICATION VOLUMES JOSÉ CALADO BARROS(1,2), MÁRIO DE CARVALHO(1,2), GOTTLIEB BASCH(1, 2) afilhamento e afilhamento completo). As doses de herbicida recomendadas para controlar estas infestantes são 2.5 a 3 l ha-1 e os volumes de água recomendados variam entre 350 e 600 l ha-1. Os resultados obtidos neste estudo, mostram que a antecipação da aplicação do herbicida para uma fase mais precoce do desenvolvimento das infestantes (início do afilhamento), conduz a um maior controlo das infestantes, mesmo utilizando-se doses e volumes de calda inferiores aos recomendados. Por sua vez, o menor controlo das infestantes e o maior período de competição destas com a cultura quando a aplicação é atrasada (afilhamento completo) conduzem a uma menor produção de grão para esta data de aplicação

Prevalence, awareness, treatment and control of hypertension, diabetes and hypercholesterolaemia among adults in Dande municipality, Angola

Objectives: To estimate the prevalence, awareness, treatment, and control of hypertension, diabetes and hypercholesterolaemia in an Angolan population aged 15 to 64 years and to determine relationships with sociodemographic, behavioural and anthropometric characteristics. Methods: A total of 2 354 individuals were assessed for behavioural, sociodemographic and physical characteristics in a cross-sectional, community-based survey. Post-stratification survey weights were applied to obtain prevalence levels. Adjusted odds ratios for each variable related to the conditions were calculated using logistic regression models. Results: Overall, the prevalence of hypertension was 18.0%, diabetes 9.2% and hypercholesterolaemia 4.0%. Among hypertensive individuals, the awareness rate was 48.5%; 15.8% were on treatment and 9.1% had their blood pressure controlled. Only 10.8% were aware they had diabetes, 4.5% were on treatment and 2.7% were controlled. The awareness level for hypercholesterolaemia was 4.2%, with 1.4% individuals on treatment and 1.4% controlled. Conclusions: The prevalence levels of hypertension and diabetes, which were higher than previous findings for the region, together with the observed low rates of awareness, treatment, and control of all conditions studied, constitute an additional challenge to the regional health structures, which must rapidly adapt to the epidemiological shift occurring in this population.info:eu-repo/semantics/publishedVersio

Weed management in winter wheat (Triticum aestivum L.) influenced by different soil tillage systems

In this study, weed management in winter wheat influenced by different soil tillage systems was investigated. The experiment was carried out under Mediterranean conditions on a Luvisol, during two growing seasons (1996/1997 and 1999/2000). Two factors (different soil tillage systems and post-emergence weed control) were studied, with two levels each: Two soil tillage systems and two levels of post-emergence weed control. The conventional soil tillage system, performed for seedbed preparation after the emergence of a high percentage of weeds, increases the appearance of monocotyledons, especially Lolium rigidum Gaud. in wheat crops, when compared to their establishment in no-till system. As a consequence of the higher number of monocotyledons there is an increase in weed-crop competition. Without post-emergence herbicide treatment, the wheat crop yield is lower in the treatments with the conventional soil tillage system and yield reduction is less under no-till system compared to the respective treatments with post-emergence herbicide application

Efeito de diferentes doses e volumes de calda do herbicida aclonifena no controlo em pré-emergência de infestantes na cultura do grão-de-bico

Nos anos agrícolas de 2015/2016 e 2016/2017, realizaram-se dois ensaios de campo, na Herdade da Almocreva (Beja) e na Herdade do Passinho (Elvas), respetivamente. O objetivo destes ensaios foi estudar o efeito de diferentes doses do herbicida de pré-emergência aclonifena, em interação com dois volumes de calda, no controlo das infestantes e na produtividade da cultura do grão-de-bico (Cicer arietinum L.). As doses de herbicida estudadas foram 1500, 1800, 2100 e 2400 g s.a ha-1, correspondendo a dose menor à mínima recomendada pelo fabricante do produto para esta cultura e a dose mais elevada, à dose máxima recomendada. Os volumes de calda aplicados foram 300 e 400 L ha-1, com os volumes recomendados a variarem entre 300 e 500 L ha-1. Quer as doses, quer os volumes de calda usados, são recomendados em Espanha, estando este herbicida, em fase final de homologação para Portugal. Verificou-se, uma maior reinfestação no segundo ano de ensaios, mas a interação ano x dose x volume não foi significativa relativamente à produção de grão por unidade de área, havendo diferenças significativas relativamente a este parâmetro, apenas para as doses de herbicida e para a interação ano x dose. A correlação entre a eficácia do herbicida e a produção de grão foi altamente significativa para os dois anos de ensaio e diferentes modalidades (dose x volume). Em cada um dos anos de ensaio, a produção de grão por unidade de área está correlacionada significativamente com o número de vagens por planta, a altura das plantas e o número de sementes por unidade de área, o mesmo não sucedendo com o número de plantas por unidade de área e com o peso médio da semente

Redução de doses de herbicidas no controle de plantas daninhas em cultivo de cevada sob condições climáticas temperadas

Yield losses in cereal crops under temperate climate conditions due to weed-crop competition, namely Lolium rigidum G., can reach up to 80%, depending on the season and infestation level. Nevertheless, the costs of chemical weed control and the environmental impact caused by herbicides recommend the search for strategies to reduce their input. Therefore, the aim of this work was to study the possibility of reducing the input of different post-emergence herbicides (diclofop-methyl + fenoxaprop–p-ethyl and amidosulfuron + iodosulfuron-methyl-sodium) to control Lolium rigidum G. and broad-leaf weeds in barley under no-till, and to monitor the effect on weed population levels and crop yields. A field experiment was carried out in 2007-2008 and 2008-2009, in an experimental farm in the south of Portugal, combining different herbicide doses applied at different weed development stages. Results show that, for all herbicide doses, the earlier application provides higher weed control efficacy and higher grain yields, indicating that the reduction of doses is possible while maintaining satisfactory crop grain yields

The effect of low post-emergence herbicide doses to control weeds and on the yield wheat in direct drilling

O objectivo do presente trabalho foi o de estudar a eficiência do herbicida Mesosulfurão- metilo & iodosulfurão-metilo sódio & mefenepir-dietilo, no controlo, em pósemergência,de infestantes mono e dicotiledóneas e na produção da cultura do trigo em sementeira directa, combinando doses inferiores às recomendadas com volumes de água também inferiores, em dois estádios de desenvolvimento das infestantes. Assim, no ano agrícola de 2004/2005, realizou-se um ensaio numa herdade privada do Concelho de Évora, em que se estudou o efeito de 3 doses do herbicida anteriormente referido (0,20; 0,30 e 0,40 kg/ha) em interacção com 3 volumes de água (100; 200 e 300 l/ha) em duas fases de desenvolvimento das infestantes (início do afilhamento e afilhamento completo no caso das monocotiledóneas e, 3/4 e 5/6 pares de folhas para as dicotiledóneas). As doses recomendadas para este herbicida nas nossas condições climáticas e de infestação, são de 0,30; 0,35 e 0,40 kg/ha e os volumes de água variam de 350 a 600 litros por hectare. Os resultados obtidos mostram ser este herbicida bastante eficiente no controlo das monocotiledóneas (Avena sterilis L. e Lolium rigidum G.), com a 1ª época de aplicação a ser significativamente melhor do que a 2ª época. No entanto, quer para as infestantes monocotiledóneas quer para as dicotiledóneas, a interacção dose x volume x época, não foi significativa. Em relação às dicotiledóneas, a eficiência foi, para a generalidade dos tratamentos, inferior à das monocotiledóneas, continuando no entanto, a 1ª época de aplicação a ser significativamente melhor que a 2ª época. No que concerne à produção de grão, constatou-se que a antecipação da aplicação do herbicida, poderá permitir não só a redução da dose como também do volume de água aplicado

The use of ore microscopy data for flotation process control by means of a liberation model - a case study

Any realistic description of ore processing dealing with a particulate system requires an adequate characterization of it properties, mainly particle size and grade,because these are the most important variables that influence the performance of a mineral processing separation, such as froth flotation. Experience has shown that an appropriate model for liberation of solid phases must always integrate all available mineralogical data by comminution. The present work aims too describe a case study for calibration of a liberation model with data obtained from semi-quantitative mineralogical analysis (ore microscopy). For the specific case of random comminution, a limit probability argument is used to justify the introduction of Euler's Beta Law as well-suited tool for describing the liberantion state of a comminuted ore, because it is able to predict the grade distribution of a given iso-size fraction of such particulate system

Effect of different doses of post-emergence-applied iodosulfuron on weed control and grain yield of malt barley (Hordeum distichum L.), under Mediterranean conditions

A study was carried out over a two year period (2009/2010 and 2012/2013) on an experimental farm in the Alentejo region (Beja), in southern Portugal where rainfed malt barley (Hordeum distichum L.) is sown at the end of autumn or beginning of winter (November– December). The aim of this experiment was to study the efficiency of the herbicide iodosulfuron-methyl-sodium to control post-emergence broadleaved weeds in this cereal crop. The malt barley crop was established using no-till farming. This technology provides the necessary machine bearing capacity of the soil to assure the post-emergence application of herbicides at two diferente weed development stages. The herbicide iodosulfuron-methyl-sodium was applied at three doses (5.0, 7.5, and 10.0 g a. i. · ha–1) and at two different broadleaved weed development stages (3 to 4 and 6 to 7 pairs of leaves), that also corresponded to two diferente crop development stages (beginning of tillering and complete tillering). The results indicated that early herbicide application timing provided a significantly higher efficiency for all the applied herbicide doses, but this better weed control was not reflected in a higher crop grain yield. The lack of a higher crop grain yield was probably due to a crop phytotoxicity of the herbicide, when used at an early application timing