Abstract:

In silty soils under no tillage (NT), platy (P) soil structure is widespread and constrains water infiltration. Our objectives were (i) to evaluate how traffic and the presence of crop residues influence P structure development in the field and (ii) to characterize changes in soil structure caused by alternation of wetting and drying (w-d) periods for two topsoil layers of a silty soil and two compaction levels in the laboratory. The five-year field experiment was carried out on a Typic Argiudoll under NT and the structure of the A horizon was analyzed using visual soil evaluation (VSE) both before and five years after two traffic levels were applied to four crop sequences. The laboratory experiment of w-d cycles was carried out with two disturbed layers of a Typic Argiudoll, which was repacked to achieve two different bulk densities, and the columns were subjected to 5, 10, or 15 w-d cycles. In the field experiment, the P structure was clearly identified by VSE and corroborated by shear strength and bulk density measurements. The proportion of P structure increased until about 50% of the A horizon after 5 years, irrespective of the traffic or presence of crop residues at the expense of the Φ structure proportion. In the laboratory, consecutive w-d cycles caused changes in soil volume, cracking of the soil surface, and formation of P structure of variable thickness up to 20 mm, confirming that alternation of w-d periods can cause structural modification of the silty soil, in particular horizontally oriented cracks. The number of w-d cycles increased the thickness of the P structure in the upper layer (R2 = 0.55) and in the compacted treatment (R2 = 0.81). The results obtained constitute important progress in the understanding of the evolution of P structure of silty soils under NT.

EEA Pergamino

Author affiliation: Sasal, Maria Carolina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná; Argentina

Author affiliation: Léonard, Joel. Institut National de la Recherche Agronomique; Francia

Author affiliation: Andriulo, Adrian Enrique. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino; Argentina

Author affiliation: Boizard, Hubert. Institut National de la Recherche Agronomique; Francia

Abstract:

Se estudiaron 13 muestras de aceite de oliva de las variedades Arbequina, Barnea, Picual, Arauco, Coratina, Frantoio y Manzanilla cosecha 2006, procedentes de La Rioja y Catamarca, mediante criterios internacionales de calidad y pureza. Los índices primarios de calidad (acidez, índice de peróxidos y coeficientes de extinción en el ultravioleta) estuvieron de acuerdo con lo propuesto por el Consejo Oleícola Internacional (COI) para aceites de oliva “vírgenes extra”. Entre otros parámetros de calidad, los aceites argentinos se destacaron por su alto contenido de tocoferoles (249 - 389 mg / kg). Los aceites de Arbequina se caracterizaron por bajos contenidos del ácido graso C18:1 (40.57 - 56.85 %) y / o altos valores de C16:1 (2.73 - 5.25 %), C16:0 (18.69 - 23.79 %). Por su parte, los aceites de Manzanilla y Picualse destacaron por contenidos ligeramente excedidos de C18:3. Los contenidos de esteroles totales (1381 - 2699 mg / kg) y el porcentaje de eritrodiol - uvaol (0.29 - 2.39%) se ajustaron a los límites legales. En Arbequina, Barnea y Arauco, se observaron elevados contenidos de campesterol (4.19 - 5.27 %) y/o bajos contenidos de sitosterol aparente (91.79 - 92.41 %). En general, Arbequina presentó contenidos de ceras C40 - C46 (236 - 523 mg/kg) superiores a los límites establecidos por el COI. Finalmente, se presentan las conclusiones generales del Proyecto trienal ASAGA - PLAPIQUI para la evaluación de aceites de oliva argentinos.

Thirteen olive oil samples from the latest crop (2006) in the Argentinian provinces of La Rioja and Catamarca, were examined by means quality and genuineness international criteria. Arbequina, Barnea, Picual, Arauco, Coratina, Frantoio, and Manzanilla varieties were evaluated. The classic quality indexes (acidity, peroxide index, and extinction coefficients in ultraviolet region) were according to the International Olive Oil Council (IOOC) normative for extra - virgin olive oils. It is outstanding the high tocopherol contents (249 - 389 mg / kg) of the Argentinian oils. Arbequina oils were characterized by low C18:1 fatty - acid percentage (40.57 - 56.85 %) and / or high values for C16:1 (2.73 - 5.25 %), C16:0 (18.69 - 23.79 %). The linolenic acid was slightly exceeded in samples from Manzanilla and Picual. The total sterol content (1381 - 2699 mg / kg) and the erythrodiol - uvaol percentage (0.29-2.39 %) satisfied the limits for virgin olive oils. High campesterol contents (4.19-5.27 %) and low apparent sitosterol contents (91.79 - 92.41 %) were observed in Arbequina, Barnea and Arauco oils. Most of the Arbequina samples had C40 - C46 wax content (236 - 523 mg / kg) beyond the limits for edible virgin olive oils. Final conclusions on the ASAGA - PLAPIQUI Project (2004 - 2006) for characterize Argentinian olive oils are also presented.

Author affiliation: Ceci, Liliana Noemí. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina

Author affiliation: Cuña, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina

Author affiliation: Melgarejo, Martha. Asociación Argentina de Grasas y Aceites (asaga); Argentina

Author affiliation: Carelli Albarracin, Amalia Antonia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina

Abstract:

The photocatalytic activity under UV and visible irradiation of a series of CeO2-TiO2 composite materials prepared by microemulsion and subsequently calcined at 500 0C was evaluated using acetaldehyde as a model pollutant. The activities of three composite catalysts containing 2.5, 5 and 25 molar % of ceria, as well as a nano-titania reference are compared by means of efficiency parameters; the quantum (or true) efficiency, as well as the photonic (or apparent) efficiency were evaluated. To this end, the lamp emission properties, as well as the radiation field interaction with the catalyst inside the reactor were modelled and numerically calculated. For the evaluation of the radiation absorbed by the catalysts, the optical properties of the materials were measured and a radiative transfer model that considers all potential optical events was built up. The stability of the systems under reaction conditions was also studied. Overall, the results evidence that the composite containing 2.5 Ce mol. % outperforms titania by a factor of at least 2, irrespective of the illumination source used in the experiment. This shows the potential of the CeO2-TiO2 composites, a highly active and stable system, for sunlight optimum profiting.

Author affiliation: Muñoz Batista, Mario. Consejo Superior de Investigaciones Cientificas. Instituto de Catálisis y Petroleoquímica; España

Author affiliation: Ballari, Maria de Los Milagros. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina

Author affiliation: Kubacka, Anna. Consejo Superior de Investigaciones Cientificas. Instituto de Catálisis y Petroleoquímica; España

Author affiliation: Cassano, Alberto Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina

Author affiliation: Alfano, Orlando Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina

Author affiliation: Fernández García, Marcos. Consejo Superior de Investigaciones Cientificas. Instituto de Catálisis y Petroleoquímica; España

Abstract:

El glifosato (N- (fosfonometil) glicina) es un post-emergencia, no selectivo, herbicida foliar. Alrededor de 200 millón de litros de este herbicida se aplican cada año en Argentina, donde la principal práctica agrícola es laboreo cero (NT), que representan el 78,5% de la tierra cultivada. En este trabajo, se estudió la adsorción del glifosato en diferentes suelos bajo manejo a largo plazo (más de 16 años) de la TN y la labranza convencional (LC). Las muestras fueron tomados de diferentes regiones de Argentina correspondientes a: Paraná suelo (PAR), un suelo franco arcilloso limoso (b37% arcilla), Manfredi (MAN) y Pergamino (PER), tanto loamsoils limosas (% de arcilla b26) .Wefound que el adsorptionwas muy alta en todos los suelos, y fue particularmente influenciado por el contenido de arcilla del suelo y la CCA y negativamente relacionado a pH y fósforo. En general, el coeficiente de adsorción (Kf) fue mayor en el CT samples.We también estudió el transporte vertical de glifosato en columnas no perturbadas (15 cm de largo) y se comparó el efecto de NT y CT. Menos de 0,24% del plaguicida aplicado en todos los suelos lixiviados. No se encontraron diferencias significativas entre el total cantidad de glifosato lixiviado entre los suelos o práctica de labranza. La concentración más alta de glifosato (67,53% de las dosis aplicadas inicialmente) se encontró en los primeros 5 cm de las columnas. La fuerte retención de glifosato a la matriz del suelo, como lo confirman los altos valores de Kf obtenidos en los estudios de las isotermas, fue el factor dominante influir en la movilidad glifosato a través del perfil del suelo.

Glyphosate (N-(phosphonomethyl) glycine) is a post-emergence, non-selective, foliar herbicide. Around 200 million liters of this herbicide are applied every year in Argentina, where the main agricultural practice is no-till (NT), accounting for 78.5% of the cultivated land. In this work, we studied the adsorption of glyphosate in different soils under long-term management (more than 16 years) of NT and conventional tillage (CT). Samples were taken from different regions of Argentina corresponding to: Paraná soil (PAR), a silty clay loam soil (< 37% clay), Manfredi (MAN) and Pergamino (PER), both silty loam soils (< 26% clay). We found that the adsorption was very high in all the soils, and it was particularly influenced by the soil clay content and CEC and negatively related to pH and phosphorus. In general, the adsorption coefficient (Kf) was higher in the CT samples. We also studied the vertical transport of glyphosate in undisturbed columns (15 cm long) and compared the effect of NT and CT. Less than 0.24% of the applied pesticide leached in all soils. No significant difference was found between the total amount of leached glyphosate between soils or tillage practice. The highest glyphosate concentration (67.53% of the initially applied doses) was found in the top 5 cm of the columns. The strong retention of glyphosate to the soil matrix, as confirmed by the high Kf values obtained in the isotherm studies, was the dominant factor influencing glyphosate mobility through the soil profile.

EEA Balcarce

Author affiliation: Okada, Elena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. INTA. Estación Experimental Agropecuaria Balcarce; Argentina

Author affiliation: Costa, Jose Luis. INTA. Estación Experimental Agropecuaria Balcarce; Argentina

Author affiliation: Bedmar, Francisco. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina

Abstract:

Adsorption of the antibiotic minocycline (MC) on cerium(IV) oxide, CeO 2, has been studied in batch experiments by performing adsorption isotherms/kinetics under different conditions of pH, supporting electrolyte concentration, and temperature. CeO 2 was composed by nanoparticles whose grain size was around 9 nm. The adsorption of MC on the studied material is strongly dependent on pH, increasing as pH decreases. The adsorption mechanism, controlled by diffusion processes, is strongly related to electrostatic attractions and H-bond formations mainly between dimethylamino, amide, carbonylic and phenolic groups of the antibiotic and the functional groups of CeO 2 nanoparticles. On the other hand, the adsorption capacity at constant pH increases as ionic strength decreases and as temperature increases. The analysis of thermodynamic parameters suggests that the adsorption on CeO 2 is endothermic and not spontaneous in nature. Ceria nanoparticles might act as an alternative adsorbent for pollution control.

Author affiliation: Brigante, Maximiliano Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

Author affiliation: Schulz, Pablo Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentina

Abstract:

La producción apícola en la región del noroeste de Chubut, está orientada principalmente a la mono producción de miel, la cual representa el principal ingreso de la actividad a los apicultores. En el valle 16 de octubre como en la comarca del paralelo 42, los promedios de consumo de miel son superiores a la media nacional que ronda los 200grs/hab/año, lo que facilita la comercialización de este producto. Los rindes de miel, son directamente afectados por cuestiones climáticas, como han sido las sucesivas sequías ocurridas, siendo poco estables a lo largo de los años, afectando la sustentabilidad del sistema productivo y la rentabilidad de los apicultores. Esto ha motivado la búsqueda de alternativas de aprovechamiento de otros productos de la colmena como polen, propóleos y cera, los cuales tienen un alto potencial para la elaboración de productos cosméticos, nutricionales y farmacéuticos. A través del presente artículo se analiza la posibilidad de que se desarrollen estas alternativas en el sector, considerando las características de la región.

EEA Esquel

Author affiliation: Ocampo, Gustavo Regino. INTA. Estación Experimental Agropecuaria Esquel. Agencia de Extensión Rural El Maitén; Argentina

Author affiliation: Boussy, Susana. Perito Apicultor Nacional; Argentina

Abstract:

The atomic and electronic structure of ceria surfaces exhibiting step edges have been studied by means of periodic density functional(LDA+U and GGA+U) calculations. A variety of stoichiometric and nonstoichiometric models of increasing complexity have been designed. The electronic structure has been explored using the topological Bader analysis, the calculated magnetic moments and the ELF (electron localization function) maps. It is concluded that Ce 3+ atoms may exist even in stoichiometric extended ceria samples and that the presence of oxygen vacancies in stepped surfaces also induces the presence of Ce3+ atoms although in both cases, the reduced atoms tend to occupy the sites with smallest possible coordination number. © 2008 American Chemical Society.

Author affiliation: Branda, Maria Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina

Author affiliation: Loschen, Christoph. Universidad de Barcelona; España

Author affiliation: Neyman, Konstantin M.. Universidad de Barcelona; España

Author affiliation: Illas, Francesc. Universidad de Barcelona; España

Abstract:

Basura Cero es el nombre genérico que reciben los planes adoptados en distintos lugares del mundo, tendientes a disminuir gradualmente la basura que se lleva a disposi ción final (o incineración), estableciendo metas concretas. Para lograr este objetivo es necesario encarar el problema a través de distintas estrategias, que pasan por la reducción en la generación de residuos, su reutilización y su reciclaje (incluyendo c ompostaje y biodigestión de residuos orgánicos). Esto implica modificar los métodos de producción con el fin de reducir la cantidad y peligrosidad de los residuos que se generan, disminuir la utilización de materias primas en esa etapa, y fabricar producto s más duraderos, con menos sustancias tóxicas, que permitan una reutilización o reciclado más fácil al final de su vida útil

Author affiliation: Panarisi, Edgardo A. Universidad Nacional de Rosario. Facultad de Ciencia Política y Relaciones Internacionales; Argentina.

Abstract:

Under no-tillage field conditions, cover crop (CC) residues remain on the soil surface and decompose at a slow rate. We used three CC species (oat, Avena sativa L.; rye, Secale cereale L.; and ryegrass, Lolium multiflorum L.) to evaluate the residue biomass decomposition and P pools release–total phosphorus (Pt), inorganic phosphorus (Pi), and organic phosphorus (Po)–under no-tillage field conditions. The dynamics of biomass and P in CC residues was evaluated through the litterbag method during two annual periods in a long-term field experiment. Exponential decay models were fitted to each variable. Biomass decomposition and P release followed asymptotic decay models for the less labile residues (oat and rye) and single exponential decay models for the more labile ryegrass residues. Biomass and Pt showed rather equivalent dynamics, but Pi release was faster (Pi rates were three times higher and Pi plateaus were two to four times lower than biomass values). The release of Pt from CC residues reached agronomically significant quantities (2–16 kg ha–1) during the cash crop growing season and most of this Pt was released as Pi (53–100%). A positive tradeoff was observed between the release of Pi, potentially available for subsequent crop, and the residue biomass remaining over the soil. This means that Pi was released from residues, but enough biomass remained on the soil surface for erosion control. These results can be incorporated into predictive models on the contribution of CC residues to soil coverage and P nutrition of subsequent crops.

EEA General Villegas

Author affiliation: Varela, María Florencia. Universidad Nacional de La Pampa. Facultad de Agronomía; Argentina

Author affiliation: Barraco, Miriam Raquel. INTA. Estación Experimental Agropecuaria General Villegas; Argentina

Author affiliation: Gili, Adriana Anahi. Universidad Nacional de La Pampa. Facultad de Agronomía; Argentina.

Author affiliation: Taboada, Miguel Angel. INTA. Instituto de Suelos; Argentina

Author affiliation: Rubio, Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; Argentina

Abstract:

This paper focuses on the preparation, characterization and analysis of the catalytic activity of a series of alumina-supported Cu and Pt catalysts modified with different amounts of cerium, in order to employ them in the carbon monoxide preferential oxidation (CO-PROX) reaction. The catalysts containing only copper as metallic phase allowed us to obtain very good conversion of CO to CO2, reaching a maximum of 70% conversion for the catalyst with higher concentration of Cu supported on the alumina modified with the highest concentration of Ce (0.54 wt% Cu, 25 wt% Ce). For catalysts containing both Cu and Pt the conversions achieved were reasonably good, although lower than for the monometallic catalysts, but at lower temperature. All the catalysts were characterized by different physicochemical techniques: temperature-programmed reduction, X-ray diffraction, UV-VIS diffuse reflectance spectroscopy and surface area. The presence of ceria in these catalysts is pointed as one of the main reasons for their good activity, mainly because the CeO2 increases the availability of O2 to be used in this oxidation reaction

Author affiliation: Núñez, Natalia Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigación y Desarrollo En Ciencias Aplicadas; Argentina. Universidad Nacional de La Plata. Facultad de Ingenieria; Argentina

Author affiliation: Bideberripe, Hernán Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigación y Desarrollo En Ciencias Aplicadas; Argentina. Universidad Nacional de La Plata. Facultad de Ingenieria; Argentina

Author affiliation: Casella, Monica Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigación y Desarrollo En Ciencias Aplicadas; Argentina

Author affiliation: Siri, Guillermo Jorge. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Centro de Investigación y Desarrollo En Ciencias Aplicadas; Argentina. Universidad Nacional de La Plata. Facultad de Ingenieria; Argentina