oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Changes in Average Annual Precipitation in Argentina’s Pampa Region and Their Possible Causes  [PDF]
Silvia Pérez,Eduardo Sierra,Fernando Momo,Marcelo Massobrio
Climate , 2015, DOI: 10.3390/cli3010150
Abstract: Changes in annual rainfall in five sub-regions of the Argentine Pampa Region (Rolling, Central, Mesopotamian, Flooding and Southern) were examined for the period 1941 to 2010 using data from representative locations in each sub-region. Dubious series were adjusted by means of a homogeneity test and changes in mean value were evaluated using a hydrometeorological time series segmentation method. In addition, an association was sought between shifts in mean annual rainfall and changes in large-scale atmospheric pressure systems, as measured by the Atlantic Multidecadal Oscillation (AMO), the Pacific Decadal Oscillation (PDO) and the Southern Oscillation Index (SOI). The results indicate that the Western Pampas (Central and Southern) are more vulnerable to abrupt changes in average annual rainfall than the Eastern Pampas (Mesopotamian, Rolling and Flooding). Their vulnerability is further increased by their having the lowest average rainfall. The AMO showed significant negative correlations with all sub-regions, while the PDO and SOI showed significant positive and negative correlations respectively with the Central, Flooding and Southern Pampa. The fact that the PDO and AMO are going through the phases of their cycles that tend to reduce rainfall in much of the Pampas helps explain the lower rainfall recorded in the Western Pampas sub-regions in recent years. This has had a significant impact on agriculture and the environment.
La pampa argentine: structures et évolution de l'espace rural  [PDF]
Marcelo Sili
Mappemonde , 1999,
Abstract: La modélisation des étapes historiques à travers des chorèmes contribue à donner une vision synthétisée de l'évolution socio-territoriale de la Pampa argentine, qui sert de base à la construction d'un scénario prospectif de la région. Ainsi, ces modèles chorématiques peuvent être utilisés comme éléments d'analyse de base et comme modèles prospectifs pour la prise de décisions et la définition de politiques territoriales à long terme.
Biomass Production, Nitrogen Accumulation and Yield in Wheat under Two Tillage Systems and Nitrogen Supply in the Argentine Rolling Pampa  [PDF]
Silvina I. Golik,Hugo O. Chidichimo,Hugo O. Chidichimo,Santiago J. Sarandón
World Journal of Agricultural Sciences , 2005,
Abstract: Biomass production and partition, total nitrogen accumulation, grain yield and yield components in wheat were evaluated along two years. In 2000, two tillage systems were analyzed: mouldboard plough and chisel plough, for two cultivars: Buck Poncho and Buck Charrúa, under three fertilization treatments: I) without N, ii) 90 kg N ha 1 in a single dose at sowing and iii) 45 kg N ha 1 at sowing + 45 kg N ha 1 at the end of tillering. In 2001, the tillage systems and fertilization treatments were the same as in the previous year. Buck Yapeyú and Buck Poncho were tested as cultivars. In 2000, during the first stages, biomass production was higher in the Conventional Tillage (CT) treatment than in Chisel (VT). Nevertheless, at maturity, no significant differences were found in biomass or grain production between the tillage systems. There were significant effects of the fertilization treatments on all growth stages analyzed. In 2001, biomass and grain yield were lower than in the previous year. At anthesis, neither the tillage systems nor the fertilization treatments led to significant differences in biomass production. At maturity, the tillage treatments caused significant effects on biomass production, total N accumulation and yield, while the different fertilization treatments no produced any effects. Biomass production, total N accumulation and yield depended on the NO3 availability, which was modified by rainfall amount and distribution and sowing date. Chisel plough was an effective tillage system, when N availability and sowing date were suitable. Nevertheless, when both sowing date and N availability were unfavorable, the conventional tillage produced a better response than that of the non-conventional tillage. When response for fertilization treatments was found, this was independent of the moment and dose applied. Cultivar yields did not show significant differences in each considered year.
Biotechnology in Argentine agriculture faces world-wide concentration
Varela,Liliana; Bisang,Roberto;
Electronic Journal of Biotechnology , 2006,
Abstract: in the 1980s, the technical pattern of production in agriculture changed due to the increasing design of genetically modified plants. modern biotechnology thrived on events requiring certain thresholds of scientific and technological skills as well as scale economies usually seen in developed countries. the mergers and acquisitions during the mid-1990s led to a world-wide oligopoly composed of very few agri-biotechnological mega-corporations and the literature discusses the impact of the mergers and acquisitions on the agriculture of developing countries with comparative advantages in agriculture. this paper analyzes the world-wide process of agri-biotechnological mega-corporation mergers and acquisitions as well as its impact and interrelationships with argentine agriculture using information from primary and secondary sources. conclusions refer to the set-backs of endogenous agri-biotechnological development due to world-wide concentration in developing countries with comparative advantage in agriculture.
Indicadores de contaminación biológica asociados a la erosión hídrica en una cuenca de Pampa Ondulada Argentina Indicators of biological contamination associated with water erosion in basin belonging the rolling pampa, Argentina
Celio I. Chagas,Juan Morettón,Oscar J. Santanatoglia,Marta Paz
Ciencia del Suelo , 2006,
Abstract: La producción agropecuaria utiliza el 70% de los recursos hídricos superficiales. Una parte de esa agua es consumida por la ganadería, principalmente en forma de bebida animal. Existe un importante riesgo de contaminación biológica del agua asociada a dicha actividad, debido a que los patógenos eliminados a través de las deyecciones y orinas animales pueden ser transportados a las vías de agua, a través del escurrimiento superficial. El presente trabajo se realizó en la cuenca del arroyo del Tala, ubicada en la Pampa Ondulada y sujeta a intensos procesos de escurrimiento y erosión hídrica. En la cuenca existen explotaciones ganaderas extensivas asociadas a suelos hidro-halomórficos cercanos a las vías de agua y una cantidad creciente de explotaciones intensivas del tipo "engorde a corral". El principal uso agropecuario del agua del arroyo y de sus tributarios es en forma de bebida animal directa. Los objetivos del presente trabajo han sido analizar mediante algunos indicadores biológicos, la posible contaminación de las aguas y sedimentos acumulados en sectores bajos representativos de la actividad pecuaria de dicha cuenca y determinar el origen de su contaminación: humana o animal. Las aguas analizadas presentaron concentraciones de indicadores biológicos del grupo de los estreptococos y enterococos fecales compatibles con procesos de contaminación fecal de origen animal pero no de origen humano. Se observó una estrecha asociación entre la concentración de coliformes totales y la presencia de sólidos sedimentables originada por erosión hídrica, en las aguas de diversos ambientes bajos de la cuenca. De esta manera se puso de manifiesto la potencialidad de los sedimentos para actuar como transportadores de bacterias, algunas de las cuales pueden ser altamente patogénicas como es el caso de Salmonella spp. Los procesos de escurrimiento, erosión hídrica y contaminación biológica han probado estar relacionados entre sí a nivel de la cuenca bajo estudio. Agriculture activities use 70% of the world water resources, partly for animal production and particularly cattle feeding. There is an outstanding risk of biological contamination associated with this kind of production because animal feces and urine containing pathogens can be transported to surface waterways through runoff. The present investigation was carried out in the Tala basin belonging to the Rolling Pampa region in which intense runoff and erosion processes are widespread. In this basin there are extensive cattle feeding farms which are located close to the natural waterways, in bottomlands with hyd
Continuities and ruptures in Argentine's regional discourse: The process of conceptual construction of the Pampa Continuidades y rupturas en el discurso regional argentino: El proceso de construcción conceptual de la Pampa  [cached]
Esteban Salizzi
Mundo agrario , 2012,
Abstract: The present article aims to compare the main proposals of regionalization of the argentine territory seeking to establish -from its survey, analysis and comparison- continuities and ruptures around the conceptual construction of the Pampa. This concern is set within the perspective that points out that regional geography -as geographical writing mode that appeals to the distinction, nomination and order of subnational entities to provide overall interpretations about the territory and society of a country-, in its various proposals, involves ways to represent and address the internal asymmetries of a society. It deepens, then, both in the various paradigms on which these proposals have been established as in the constructions that these have developed of the region in question. Geographical unit that has been repeatedly imagined as possessing a supposed centrality based on the population and industrial weight, the level of agricultural productivity, the generating of huge economic wealth, its history, and the agglutinating/articulating role of the economy and politics El presente artículo tiene como objetivo comparar las principales propuestas de regionalización del territorio argentino buscando establecer -a partir de su relevamiento, análisis y comparación- continuidades y rupturas en torno a la construcción conceptual de la Pampa. Esta preocupación se establece dentro de la perspectiva que se ala que la geografía regional -en tanto modalidad de escritura geográfica que apela a la distinción, nominación y ordenamiento de entidades subnacionales para ofrecer interpretaciones de conjunto sobre el territorio y la sociedad de un país-, en sus diversas propuestas, implica modos de representar y de abordar las asimetrías internas de una sociedad. Se profundiza, entonces, tanto en los diversos paradigmas sobre los cuales se han establecido dichas propuestas como en las construcciones que estas han desarrollado de la región en cuestión. Se trata de una unidad geográfica que ha sido recurrentemente imaginada como poseedora de una supuesta centralidad basada en el peso demográfico e industrial, el nivel de la productividad agropecuaria, la generación de grandes riquezas económicas, su historia, y el rol aglutinador/articulador de la economía y la política
Effects of supplementary irrigation on chemical and physical soil properties in the rolling pampa region of Argentina
Mon,Rodolfo; Irurtia,Carlos; Fernando Botta,Guido; Pozzolo,Oscar; Bellora Melcón,Fernando; Rivero,David; Bomben,Miguel;
Ciencia e investigación agraria , 2007, DOI: 10.4067/S0718-16202007000300002
Abstract: the effects of supplementary irrigation on soil chemical and physical properties were studied in 21 locations in the north of the rolling pampa region of argentina. the chemical and physical variables were measured in top soil (0-100 mm) to compare irrigated and non-irrigated soils. chemical variables were: electrical conductivity (ec), ph, exchangeable sodium percentage (esp), and organic mater content. physical variables included structural index (si) and percolation index (pi) measured in the laboratory, as well as infiltration, runoff, and soil losses, measured in the field with a small portable rainfall simulator. water quality was established according to its chemical composition and riverside usa classification. in irrigated soils, chemical data shows, on average, a slight increase in esp (from 2.56 to 5.52) and in ph (from 6.13 to 6.45). ec, si, and pi show the same values in irrigated and non-irrigated soils. the application of a simulated rainfall of 30 mm in 30 min revealed a different soil behavior. irrigated soils present lower values of water entry and infiltration rates, and higher values of runoff and soil losses. the variation in chemical and physical soil properties show that within 10 years of supplementary irrigation a slight process of sodication and alkalinization occurs. water quality and soil chemical data suggest that the sodication process and the increased soil erosion risk must be controlled in order to achieve a sustainable high production system
Movimiento del agua en Argiudoles de la Pampa Ondulada con diferente mineralogía de arcillas Water movement in some Argiudolls of the rolling Pampa differing in their clay mineralogy  [cached]
Mario Guillermo Castiglioni,Héctor José María Morrás,Oscar José Santanatoglia,María Victoria Altinier
Ciencia del Suelo , 2007,
Abstract: Los suelos zonales de la Pampa Ondulada son Argiudoles Típicos y Vérticos los cuales se diferencian en la composición mineralógica de su fracción arcilla. El objetivo del presente trabajo fue analizar las vinculaciones entre la tasa de movimiento del agua edáfica con algunos atributos relacionados con la composición mineralógica de la fracción arcilla, en distintos suelos representativos de la región mencionada. Se tomaron muestras de los horizontes A, BA/BE, Bt y BC de dos Argiudoles Típicos y de un Argiudol Vértico, realizando sobre las mismas determinaciones relacionadas con la cantidad y tipo de las arcillas presentes. A su vez mediante diferentes técnicas se evaluaron el sistema poroso del suelo y el movimiento de agua edáfica. En los horizontes Bt, aquellos parámetros que integran el tipo y el contenido de arcillas, como el COLE y la CIC, mostraron estar mejor vinculados con el movimiento de agua edáfica que cuando se consideró únicamente el porcentaje de arcilla. La distinta porosidad estructural generada dentro de los agregados de los horizontes Bt, originó diferencias en su difusividad y conductividad hidráulica no saturada, a contenidos de humedad por encima del 50% de saturación. En aquellos horizontes con mayor actividad biológica y menor contenido de arcilla, el movimiento de agua se realizó en forma independiente de las características de las arcillas presentes. Typic and Vertic Argiudolls, which differ in the composition of their clay fraction, are the zonal soils in the Rolling Pampa of Argentina. The aim of this work has been to analize the relationship between water movement and diverse soil properties in some representative soils of the Rolling Pampa, differing in their clay mineralogy. The A, BA/ BE, Bt and BC horizons of two Typic and one Vertic Argiudolls were sampled and a number of properties related with clay content and clay type were measured. Soil porosity and soil water movement were also evaluated through different techniques. In the Bt horizons, those parameters integrating clay type together with clay content, as COLE and CEC, have shown a better relationship with soil water movement than considering clay quantity alone. Clods from Bt horizons of studied soils have shown to differ in their internal structural porosity and this led to different diffusivity and unsaturated (at 50% water holding capacity) hydraulic conductivity results. In upper soil horizons, characterized by a lower clay content and a greater biological activity, water movement was not related to clay mineralogy.
Germination Conditions for Cebadilla de Agua (Glyceria multiflora Steudel), a Native Grass of the Flooding Pampa Rangeland (Argentine)
Rossi Carlos Alberto,Ferrari Liliana,Postulka Estela
International Journal of Botany , 2006,
Abstract: Mature inflorescences of Cebadilla de Agua (Glyceria multiflora Steudel), were obtained from five sites, in the Flooding Pampa, in the Buenos Aires Province, Argentina. A four factor completely randomized design with four replications was applied. Treatments combined original sites, pre chilled at 7°C for 72 h (present or absent), substrate moistened with 0.2% solution of potassium nitrate (KNO3) (present or absent) and three levels of alternating germination temperatures: 15-10, 20-10 or 20-15°C in 8/16 h light/dark periods. The germination value recorded was percentage of germination of normal seedlings; Afterwards, the germination rate and uniformity were calculated. ANOVA, Tukey tests and correlations were performed. The five origins had a similar performance (93% of the total germination) when the temperature alternating of germination was 20-10 and 20-15°C in 8/16 h light/dark periods with KNO3 and 20-10°C pre chilled. The KNO3 solution positively enhanced the germination response. Higher germination rates were obtained with 20-15°C pre chilled + KNO3 as well as with 20-15°C KNO3. Pre chilled effect was related to germination temperature. When the total germination, rate and synchronization were considered, 20-15°C with KNO3 was stated as optimal germination condition of Glyceria multiflora for all sites of collection.
Análisis de los escurrimientos de una microcuenca de Pampa Ondulada bajo diferentes sistemas de labranza Runoff analysis of a watershed belonging to the rolling Pampa under different tillage systems  [cached]
Mario G. Castiglioni,Celio I. Chagas,Marcelo J. Massobrio,Oscar J. Santanatoglia
Ciencia del Suelo , 2006,
Abstract: La tasa de escurrimiento del agua juega un rol crítico en la determinación de la pérdida de suelo en las tierras agrícolas. En la última década la siembra directa se ha difundido en la Pampa Ondulada en forma considerable, siendo escasos los estudios a nivel microcuenca en los cuales se analice sus efectos sobre los escurrimientos respecto a otros sistemas de labranza. El objetivo del presente trabajo fue comparar distintos parámetros correspondientes a la respuesta hidrológica superficial de una microcuenca de la Pampa Ondulada, ante cambios en los sistemas de labranza empleados. La microcuenca bajo estudio posee una superficie de 300 ha y está ubicada en la vertiente norte de la cuenca media del Arroyo del Tala, San Pedro, provincia de Bs. As. Los suelos presentes corresponden a la serie Ramallo (Argiudol vértico) y sus fases por erosión. Se confeccionaron los hidrogramas y hietogramas correspondientes a las distintas tormentas ocurridas durante el período 1995-2002, analizándose los escurrimientos en forma global y los tramos ascendentes y descendentes de los caudales de agua obtenidos en forma separada. El sistema de labranza siembra directa originó valores de curva número mayores respecto al sistema convencional. La duración de los escurrimientos fue mayor bajo siembra directa debido a un alargamiento de la fase descendente de los hidrogramas. Los caudales de escurrimiento generados por unidad de lluvia caída fueron siempre menores bajo el sistema de siembra directa respecto al sistema de labranza convencional. Los milímetros escurridos durante la fase descendente de los hidrogramas no fue diferente entre sistemas de labranza ya que el menor caudal registrado bajo la siembra directa fue compensado por una mayor duración de este período en dicho sistema de labranza. The runoff rate constitutes a key factor in the determination of soil losses in arable lands. In the last decade, no tillage system became widespread in the Rolling Pampa. However, scarce studies have been carried out in a watershed scale about its effects on runoff dynamics, as compared to other tillage systems. The aim of the present study was to compare different parameters related to the surface runoff response of a watershed associated with changes in the tillage systems. The studied watershed has 300 ha and is located in the Northern part of the mid basin of the Tala river in San Pedro, Buenos Aires Province. The soils belong to the Ramallo Series (Vertic Argiudoll) and its eroded phases. Hydrographs and hietographs belonging to different storms that took place through the period 1
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.