Loose and baled corn cob management and storage in field effects on subsequent crop growth and soil health

Companies in the U.S have started using corn (Zea mays L.) residue as feedstock for cellulosic ethanol production. However, concerns including field storage and removal methods effects on crop growth and development, soil health, and environmental quality have been raised requiring the investigation of management and strategies to mitigate such effects. In the Mid-west corn cob have being utilized as feedstock material for cellulosic ethanol production in addition to corn residue. Nevertheless, there are many management issues that need to be addressed in order to efficiently store and remove corn cob from the field with minimum damage to subsequent crops and soil health. The current practices include the storage of loose corn cob mixed with corn residue as piles and bales at the edge of harvested fields over winter for later use in ethanol production. The corn cob residue refers to the mixture of corn cob and corn stover in the loose and baled corn cob treatments used in this experiment. Unfavorable plant growth responses have been observed after storing corn cob residue in the field. The objectives of this study were 1) to investigate the effects of loose and baled corn cob residue storage methods and management practices on plant development and crop yield, 2) evaluate and understand the effects of both methods on soil health, and 3) determine the effects of different amounts of loose corn cob residue left after removal and management practices on greenhouse gas (CO2 and N2O) emission and management practices to mitigate such effects. The study investigated two storage methods at two different sites that were established in fall of 2010. Trials ran through the fall 2012. The loose corn cob residue study was conducted at the Agronomy Research Farm at Iowa State University located near Ames, Iowa (AC site). The soil type is Canisteo silty clay loam (Fine-loamy, mixed, superactive, calcareous, mesic Typic Endoaquolls) and Harps loam (Loam, mixed, superactive, mesic Typic Calciaquolls). The treatments for the loose corn cob residue method consisted of two randomized tillage systems conventional tillage (CT) and no-tillage (NT), which represented the main treatment. Each tillage system was split into five corn cob residue treatments as Control, Removed Residue (7.5 cm applied in the fall and completely removed early spring), 2.5, 5.0, and 7.5 cm corn cob residue depths randomly assigned at each tillage treatment and replication. Then each corn cob residue treatment was split to receive four N fertilizer rates of 0, 90, 180, and 270 kg N ha-1 randomly assigned at each corn cob residue treatment and replication. The N fertilizer was 32% liquid UAN (NH4NO3), which was side-dressed and injected in May after planting using a spoke point injector. The AC site was planted on 6th May, 2011 and 14th May, 2012 using a 111 day maturity corn variety (P33W84) with a seeding density of 79,000 seeds ha-1. The second study was established at a Northwest Iowa farmer\u27s field near Emmetsburg and near the POET, Biorefinery plant (ENW site). The soil type is Clarion loam (Fine-loamy, mixed, superactive, mesic Typic Hapludolls). The ENW site used a square corn cob residue bale as a storage method, in which bales were placed in the field after harvest and stored over winter, but removed in the spring before planting. The main treatment consisted of corn cob residue left after bales removal: 1) Corn cob residue left after bales removal as a result of breakdown of bales if any, 2) corn cob residue completely cleaned or removed from each plot, and 3) the control treatment, where no bales were placed on plots. Each of the corn cob residue treatments were split into four N fertilizer rates of 0, 90, 180, and 270 kg N ha-1 and randomly assigned at each corn cob residue treatments. The different N fertilizer rates were hand applied using granular urea in May after planting. The ENW site was planted on 5th May, 2011 and 25th April, 2012 using a 111 day maturity corn variety (P0448AM1), with a seeding density of 89,000 seeds ha-1. Field data collection and measurements for plant, soil, and other parameters were conducted at both sites on weekly, monthly, and seasonal basis. These measurements included plant growth and development parameters, soil physical, chemical, and biological properties such as, soil organic carbon (SOC), soil total nitrogen (STN), microbial biomass (MBC), soil pH, organic acids (only at the AC site), soil penetration resistance (SPR), water stable aggregates (WSA), soil bulk density (ρb), and soil water infiltration rate (Ir only at the AC site only). Also, measurements of greenhouse gas emission (CO2 and N2O) were monitored along with soil mineral N (NO3-N and NH4-N), soil temperature, and moisture at the AC site only. The findings of the loose corn cob residue study suggest that plant growth and development were negatively affected by the presence of loose corn cob residue. In general, the emergence rate index (ERI), extended plant leaf heights, above-ground biomass and grain yield are negatively affected when corn cob residue is left on the soil surface after pile removal. Tillage systems show no difference in preventing the effects of corn cob residue, but it was observed that NT showed a slight advantage over CT, for plant growth and development. As expected N fertilizer at the agronomic rate (180 kg/ha) helped plant development and growth. Above-ground biomass and grain organic C and N concentrations were affected by the increase of N fertilizer rates, but not by other management practices such as tillage or corn cob residue treatments. Additionally, soil biological and chemical properties such as, SOC, STN, soil pH, and organic acids were not affected by different management practices. Changes in MBC values were affected at different times in the growing season by corn cob residue treatments. The highest soil MBC concentration was observed at the 2.5 cm and 7.5 cm corn cob residue treatments, especially in June and July (mid-summer) compared to the control and removed corn cob residue treatments. Also, soil organic acids concentrations of oxalic and butyric were the most detectable in the soil with all residue treatments in 2011 only. However, the findings suggest that soil physical properties such as, WSA, ρb, SPR, and Ir were affected by the amounts of corn cob residue left on the soil surface. The results showed a decrease in soil macro-aggregates percentage across all corn cob residue treatments due to seasonal variability as moisture condition changed. The SPR was affected by the amount of corn cob residue left on the soil surface and the degree of residue removal, where machinery and human traffic led to increase in soil compaction. Soil ρb was lower at the 0-7.5 cm soil depth in general compared with lower soil depths, and Ir was also affected by corn cob residue under the CT tillage system, where 2.5 cm and 7.5 cm corn cob residue showed higher Ir than that under control and removed at all N fertilizer rates. At the AC site soil CO2 and N2O were monitored along with soil mineral N (NO3-N and NH4-N), soil moisture, and soil temperature. The findings from the study suggested that soil CO2 and N2O emission were higher under the 2.5 cm and 7.5 cm corn cob residue treatments than the control and removed treatments. Soil moisture and soil temperature were also affected by the level of corn cob residue treatments covering the soil surface, which subsequently affected soil CO2 and N2O emission. Also, soil N2O emission was affected by N fertilizer rates, where higher N fertilizer rates caused higher soil N2O emission. It was also observed that dry conditions in 2012 decreased soil CO2 and N2O emission across all management practices, due to lower soil moisture and high soil temperatures. The soil CO2 and N2O emission were affected by corn cob residue left after removal, where areas with excessive amounts of corn cob residue on soil surface showed greater CO2 and N2O emission rates than clean areas. In the corn cob residue bale study, findings suggest that plant growth and development are not greatly impacted by the presence of corn cob residue left after bale removal from the site. It was observed that a minimum amount of corn cob residue was left on the soil surface after bales removal. In general, ERI, extended plant leaf heights, plant population, vegetative growth stages, above-ground biomass, and grain yield for clean and left corn cob residue treatments were slightly lower than control where no corn cob residue bales were placed. Over the study period no changes were observed in organic C and N concentrations of the above-ground biomass and grain. Nonetheless, corn cob residue bale storage on the field showed some changes in the SOC and STN contents at different soil depths. In general, changes in SOC and STN contents were similar across all corn cob residue treatments within each soil depth. However, at the top 7.5 cm soil depth greater SOC and STN content were observed compared to lower soil depths across all corn cob residue treatments. Also, soil pH at the top 7.5 cm soil depth was lower than that at lower soil depths across all corn cob residue treatments. Soil MBC concentration was also monitored during the corn cob residue bales study, where in general no corn cob residue treatment effect on MBC was observed within each soil sampling period for both years. However, greater MBC values were observed in the fall for both years across all corn cob residue treatments than early spring. The increase in MBC concentrations can be due to increase in organic matter and its decomposition when left on the soil surface after harvest and removal of corn cob residue bales. At the ENW site physical properties were affected by the storage of corn cob residue bales, where soil macro-aggregates stability and associated C content across all corn cob residue treatments showed a decline by the end of the experiment. While an increase for those parameters associated with micro-aggregates was observed, changes in ρb were mostly found at the top 7.5 cm soil depth across all corn cob residue treatments which are consistent with the increase in SPR values at the same depth. The greatest SPR values are observed in areas where corn cob residue bales were stored. The most effective practices in mitigating corn cob residue effects on plant growth and development, soil physical and chemical properties, and soil CO2 and N2O emission are adequate control of field machinery traffic for corn cob residue removal and corn cob residue cleaning. Field machinery for removal of loose and baled corn cob residue should be conducted under suitable conditions (i.e. dry soil condition) to minimize soil compaction during the removal of corn cob residue left on the soil surface. Such management practices can reduce corn cob residue effects on corn productivity and soil health (physical, biological, and chemical optimum functions). Also, an adequate application of N fertilizer rates will help reduce corn cob residue effect of N-immobilization and subsequent effects on plant development

Prevalencia de brucella canis en Perros Domesticos en el Barrio Salache, Provincia de Cotopaxi.

The project reseach is focused on investigating the presence of Brucella canis infection, by detecting antibodies in dogs from at-risk populations in the Salache neighborhood, Latacunga Canton, Cotopaxi province, which mainly come from serological studies with specific antigens which will be obtained from varied results depending on the province and origin of the animals. Canine Brucellosis is present throughout the world, being its total prevalence, resulting in 11% of contagion of the universes studied worldwide and being also a source of direct infection to man because it is considered a zoonotic disease that is seen reflected with reproductive problems in that who suffer from it. The data collected in this study of canine brucellosis prevalence come from serological studies, being reflected depending on the place and the sector that has carried out this research, obtaining a favorable result that initiates a total control of this pathology in domestic canines and its owners.El proyecto está enfocado en investigar la presencia de la infección por Brucella canis, mediante la detección de anticuerpos en perros procedentes de poblaciones de riesgo en el barrio Salache, Cantón Latacunga de la provincia de Cotopaxi, los cuales proceden principalmente de estudios serológicos con antígenos específicos, que se obtendrán de resultados muy variados en función a la provincia y origen de los animales. La Brucelosis canina está presente en todo el mundo, siendo su prevalencia total, teniendo como resultado un 11% de contagio de los universos estudiados a nivel mundial y siendo también una fuente de contagio directo al hombre porque es considerada como una enfermedad zoonótica que se ve reflejado con problemas reproductivos en quienes la padecen. Los datos recopilados en este estudio de prevalencia de brucelosis canina, proceden de estudios serológicos, siendo reflejado en función del lugar y el sector que se ha realizado dicha investigación, obteniendo un resultado favorable que da inicio a un control total de ésta patología en caninos domésticos y sus propietarios

Escenarios de la ordenación territorial: modelos prospectivos del uso de suelo en el cantón Cuenca

La generación de escenarios para la ordenación territorial mediante modelos prospectivos de uso de suelo representa una oportunidad para anticipar, prevenir y mitigar modalidades insostenibles de consumo y producción que tiene el desarrollo territorial. Esta investigación tiene por objeto contribuir a la generación de escenarios territoriales mediante la prospectiva de usos de suelo rural. La metodología se basó en la aplicación de prospectiva estratégica y el modelo CA_Markov, mismo que se sintetiza en: a) generación de mapas de cobertura y uso de suelo de los años 2000, 2008 y 2018, a1) análisis de cambios de uso de suelo entre los diferentes periodos, a2) cálculo de áreas de probabilidad de transición (Markov Chain); b) generación de mapas de idoneidad de transición a través de: identificación de factores de cambio, restricciones, funciones de membresía difusa (Fuzzy), modelos de proceso de jerarquía analítica (AHP) y evaluación multicriterio (MCE); c) evaluación del poder predictivo del modelo a través del índice de Kappa y; d) simulación de escenarios al año 2030. Los resultados para el periodo 2000 – 2018 indican disminución de coberturas naturales e incremento de zonas antrópicas y tierras agropecuarias. Por su parte, en los escenarios proyectados al año 2030 esta tendencia se mantendrá. Se concluye que el análisis espacio temporal para la construcción de escenarios territoriales representa no solo una alternativa para comprender la dinámica territorial, sino que permite influir en él, a través de la toma de decisiones basado en los criterios técnicos, académicos, planificadores y sociedad civil, cuya visión permita alcanzar un desarrollo sostenible del cantón Cuenca a futuro.The generation of scenarios for territorial planning through prospective models of land use represents an opportunity to anticipate, prevent, and mitigate unsustainable patterns of consumption and production that territorial development has. This research aims to contribute to the generation of territorial scenarios through the prospective of rural land. The methodology was based on the application of strategic prospective and the CA_Markov model, which is synthesized in a) generation of land cover and land use maps for the years 2000, 2008, and 2018, a1) analysis of changes in land use between the different periods, a2) calculation of transition probability areas (Markov Chain); b) generation of transition suitability maps through identification of change factors, restrictions, fuzzy membership functions (Fuzzy), analytical hierarchy process (AHP) models and multi-criteria evaluation (MCE); c) evaluation of the predictive power of the model through the Kappa index and; d) simulation of scenarios to the year 2030. The 2000-2018 period results indicate a decrease in natural coverage and an increase in anthropic zones and agricultural land. In the scenarios projected for the year 2030, this trend will continue. It is concluded that the space-time analysis for the construction of territorial scenarios represents not only an alternative to understanding the territorial dynamics but also allows to influence it through decision-making based on the technical, academic, planner, and civil society criteria, whose vision allows for achieving sustainable development of the Cuenca canton in the future.Magíster en Ordenación del TerritorioCuenc

Saberes ancestrales e interculturalidad del pueblo Cofán

The Cofán people are an Amazonian community, located on the Colombian-Ecuadorian border, for years they have struggled to survive different circumstances such as little recognition in society to the invasion and expropriation of their ancestral lands. The purpose of this study is to analyze the ancestral knowledge and interculturality of the Cofán people. For its development, documentary research was used, supported by the transfer technique and work sheets as an instrument, which allowed organizing, systematizing and analyzing the information obtained. The results of the research show that the ancestral knowledge of the Cofán people is an important pillar for the construction of Ecuadorian interculturality, understood as the radical questioning of the hegemonic logic of the Nation-State project. In this sense, it is important that the peoples and nationalities, particularly the Cofán people, spread their culture, knowledge, practices, customs and traditions without the fear of being marginalized or excluded by the dominant power and culture.El pueblo Cofán es una comunidad amazónica, ubicada en la frontera colombo-ecuatoriana, durante años ha luchado por sobrevivir a las diferentes circunstancias como el escaso reconocimiento frente la sociedad hasta la invasión y expropiación de sus tierras ancestrales. El presente estudio tiene el propósito de analizar los saberes ancestrales e interculturalidad del pueblo Cofán. Para su desarrollo se utilizó la investigación documental, sustentada con la técnica del fichaje y como instrumento las fichas de trabajo, las mismas que permitieron organizar, sistematizar y analizar la información obtenida. Los resultados de la investigación demuestran que los saberes ancestrales del pueblo Cofán son un pilar importante para la construcción de la interculturalidad ecuatoriana, entendida esta como el cuestionamiento radical a la lógica hegemónica del proyecto Estado-nación. En este sentido, es importante que los pueblos y nacionalidades, particularmente el pueblo Cofán, difundan su cultura, conocimientos, prácticas, costumbres y tradiciones sin el temor de ser marginados o excluidos por el poder y cultura dominantes. &nbsp

La natación como complemento para el mejoramiento de flexibilidad y coordinación en futbolistas del Club Deportivo Gloria

El propósito de la presente investigación es comprobar la efectividad del programa de actividades de natación, en el aumento y desarrollo de flexibilidad junto con la coordinación, abordando al ser humano como un complejo holístico, es decir, considerándolo desde sus diversas dimensiones. En el estudio participan 24 jugadores, con edades entre los 18 y los 25 años del club deportivo Gloria, de la ciudad de Cuenca. En la metodología descriptiva y de campo se aplicaron los diferentes test: de Test de Sit and Reach, Test de escalera, y Test táctico de flexibilidad hombro-muñeca. Los resultados fueron analizados estadísticamente. De forma concreta sobre las teorías que sustentan el proyecto de intervención son las referidas por las ciencias aplicadas al deporte y sintetizadas en el enfoque de los principios del entrenamiento deportivo como son la multilateralidad y el principio de transferencia que pretende un desarrollo integral y variado utilizando la natación como complemento para el mejoramiento de la flexibilidad y coordinación en el futbolista. La investigación pretende demostrar, la importancia que tienen los juegos, los ejercicios en el agua, en el trabajo de la multilateralidad, como principio básico en la formación integral y complemento del desarrollo deportivo. Hay que tener en cuenta que los ejercicios específicos también contribuyen al desarrollo de las capacidades coordinativas, contribuyendo así en la formación motriz.The aim of this research is to prove the effectiveness of swimming activities program in the enhancement of flexibility development and coordination. This research addresses the human being as a holistic complexity considering it from its several dimensions. In this investigation participated 24 soccer players from 18 to 25 years old from the Sport Club “Gloria” in Cuenca-Ecuador. Additionally, the descriptive and field methodology will apply Sit and Reach Test, Ladder Test, and Tactical shoulder-wrist flexibility test. The outcomes will be statistically analyzed. In short, the theories that support the intervention project are the ones that refer to sciences applied to sport and summarized in principles of the approach of the entertainment sport such as the multilateralism and transfer principle. These principles aim to boost the integral and varied development applying the swimming sport as a complement to improve coordination and flexibility in a soccer player. This paper aims to show the importance of games, exercises in the water in multilateralism work as a basic principle about the integral training and complement of sport development. It is important take into consideration that specific exercises also promote the development of coordinative skills, thus contributing to multilateral motor training.Licenciado en Ciencias de la Educación en Cultura FísicaCuenc

Implementación de un panel fotovoltaico mediante un estudio de captación de energía para un prototipo de vehículo impulsado por energía solar.

Se realizó la implementación de un panel fotovoltaico mediante un estudio de captación de energía para un Con la finalidad de obtener datos de radiación disponible se realizó un estudio en la ciudad de Riobamba en el mes de octubre del 2018, con la obtención de estos datos se procedió a implementar un sistema de captación de energía, por medio de módulos solares, estos se los escogió verificando que sean los de mejor rendimiento en el mercado cumpliendo con los requerimientos de consumo de energía para así poner en funcionamiento un prototipo de vehículo impulsado por energía solar, teniendo en cuenta los parámetros de diseño del arreglo fotovoltaico que está limitado por el área disponible del vehículo eléctrico, a través de ciertos cálculos se obtiene, demanda energética que está en función de la capacidad instalada , radiación sobre una superficie inclinada que está en función de la latitud del lugar de estudio , horas de sol, rendimiento global del sistema fotovoltaico que está en función de la eficiencia de pérdidas por suciedad, cables de conexión, regulador de carga, potencia pico del sistema fotovoltaico, numero de celdas a utilizar. Con la obtención de estos valores se puede determinar la eficiencia real de la matriz fotovoltaica. Se puede considerar para la mejor obtención de datos de radiación solar instalar el dispositivo de medición correctamente, para así obtener datos confiables.The implementation of a photovoltaic panel was carried out. In order to obtain the radiation data, it has been converted into a study in the city of Riobamba in October 2018, with the obtaining of these data an energy capture system has been implemented, in the middle of the solar modules, the have selected the best performance in the market meeting the requirements of energy consumption to put into operation a prototype vehicle powered by solar energy, taking into account the design parameters of the photovoltaic array that is limited by the available area of the electric vehicle, through certain calculations is obtained, energy demand that is a function of the installed capacity, radiation on an inclined surface that is a function of the latitude of the place of study, hours of sum, overall performance of the photovoltaic system that is a function of the efficiency of losses due to dirt, connection cables, charge regulator, peak power of the photovoltaic system ,number off cells to be used. By obtaining these values, the real efficiency of the photovoltaic matrix can be determined. It is recommended to consider installing the measuring device correctly, in order to obtain reliable data for the best obtaining of solar radiation data

Loose and baled corn cob management and storage in field effects on subsequent crop growth and soil health

Companies in the U.S have started using corn (Zea mays L.) residue as feedstock for cellulosic ethanol production. However, concerns including field storage and removal methods effects on crop growth and development, soil health, and environmental quality have been raised requiring the investigation of management and strategies to mitigate such effects. In the Mid-west corn cob have being utilized as feedstock material for cellulosic ethanol production in addition to corn residue. Nevertheless, there are many management issues that need to be addressed in order to efficiently store and remove corn cob from the field with minimum damage to subsequent crops and soil health. The current practices include the storage of loose corn cob mixed with corn residue as piles and bales at the edge of harvested fields over winter for later use in ethanol production. The corn cob residue refers to the mixture of corn cob and corn stover in the loose and baled corn cob treatments used in this experiment. Unfavorable plant growth responses have been observed after storing corn cob residue in the field. The objectives of this study were 1) to investigate the effects of loose and baled corn cob residue storage methods and management practices on plant development and crop yield, 2) evaluate and understand the effects of both methods on soil health, and 3) determine the effects of different amounts of loose corn cob residue left after removal and management practices on greenhouse gas (CO2 and N2O) emission and management practices to mitigate such effects. The study investigated two storage methods at two different sites that were established in fall of 2010. Trials ran through the fall 2012. The loose corn cob residue study was conducted at the Agronomy Research Farm at Iowa State University located near Ames, Iowa (AC site). The soil type is Canisteo silty clay loam (Fine-loamy, mixed, superactive, calcareous, mesic Typic Endoaquolls) and Harps loam (Loam, mixed, superactive, mesic Typic Calciaquolls). The treatments for the loose corn cob residue method consisted of two randomized tillage systems conventional tillage (CT) and no-tillage (NT), which represented the main treatment. Each tillage system was split into five corn cob residue treatments as Control, Removed Residue (7.5 cm applied in the fall and completely removed early spring), 2.5, 5.0, and 7.5 cm corn cob residue depths randomly assigned at each tillage treatment and replication. Then each corn cob residue treatment was split to receive four N fertilizer rates of 0, 90, 180, and 270 kg N ha-1 randomly assigned at each corn cob residue treatment and replication. The N fertilizer was 32% liquid UAN (NH4NO3), which was side-dressed and injected in May after planting using a spoke point injector. The AC site was planted on 6th May, 2011 and 14th May, 2012 using a 111 day maturity corn variety (P33W84) with a seeding density of 79,000 seeds ha-1. The second study was established at a Northwest Iowa farmer's field near Emmetsburg and near the POET, Biorefinery plant (ENW site). The soil type is Clarion loam (Fine-loamy, mixed, superactive, mesic Typic Hapludolls). The ENW site used a square corn cob residue bale as a storage method, in which bales were placed in the field after harvest and stored over winter, but removed in the spring before planting. The main treatment consisted of corn cob residue left after bales removal: 1) Corn cob residue left after bales removal as a result of breakdown of bales if any, 2) corn cob residue completely cleaned or removed from each plot, and 3) the control treatment, where no bales were placed on plots. Each of the corn cob residue treatments were split into four N fertilizer rates of 0, 90, 180, and 270 kg N ha-1 and randomly assigned at each corn cob residue treatments. The different N fertilizer rates were hand applied using granular urea in May after planting. The ENW site was planted on 5th May, 2011 and 25th April, 2012 using a 111 day maturity corn variety (P0448AM1), with a seeding density of 89,000 seeds ha-1. Field data collection and measurements for plant, soil, and other parameters were conducted at both sites on weekly, monthly, and seasonal basis. These measurements included plant growth and development parameters, soil physical, chemical, and biological properties such as, soil organic carbon (SOC), soil total nitrogen (STN), microbial biomass (MBC), soil pH, organic acids (only at the AC site), soil penetration resistance (SPR), water stable aggregates (WSA), soil bulk density (ρb), and soil water infiltration rate (Ir only at the AC site only). Also, measurements of greenhouse gas emission (CO2 and N2O) were monitored along with soil mineral N (NO3-N and NH4-N), soil temperature, and moisture at the AC site only. The findings of the loose corn cob residue study suggest that plant growth and development were negatively affected by the presence of loose corn cob residue. In general, the emergence rate index (ERI), extended plant leaf heights, above-ground biomass and grain yield are negatively affected when corn cob residue is left on the soil surface after pile removal. Tillage systems show no difference in preventing the effects of corn cob residue, but it was observed that NT showed a slight advantage over CT, for plant growth and development. As expected N fertilizer at the agronomic rate (180 kg/ha) helped plant development and growth. Above-ground biomass and grain organic C and N concentrations were affected by the increase of N fertilizer rates, but not by other management practices such as tillage or corn cob residue treatments. Additionally, soil biological and chemical properties such as, SOC, STN, soil pH, and organic acids were not affected by different management practices. Changes in MBC values were affected at different times in the growing season by corn cob residue treatments. The highest soil MBC concentration was observed at the 2.5 cm and 7.5 cm corn cob residue treatments, especially in June and July (mid-summer) compared to the control and removed corn cob residue treatments. Also, soil organic acids concentrations of oxalic and butyric were the most detectable in the soil with all residue treatments in 2011 only. However, the findings suggest that soil physical properties such as, WSA, ρb, SPR, and Ir were affected by the amounts of corn cob residue left on the soil surface. The results showed a decrease in soil macro-aggregates percentage across all corn cob residue treatments due to seasonal variability as moisture condition changed. The SPR was affected by the amount of corn cob residue left on the soil surface and the degree of residue removal, where machinery and human traffic led to increase in soil compaction. Soil ρb was lower at the 0-7.5 cm soil depth in general compared with lower soil depths, and Ir was also affected by corn cob residue under the CT tillage system, where 2.5 cm and 7.5 cm corn cob residue showed higher Ir than that under control and removed at all N fertilizer rates. At the AC site soil CO2 and N2O were monitored along with soil mineral N (NO3-N and NH4-N), soil moisture, and soil temperature. The findings from the study suggested that soil CO2 and N2O emission were higher under the 2.5 cm and 7.5 cm corn cob residue treatments than the control and removed treatments. Soil moisture and soil temperature were also affected by the level of corn cob residue treatments covering the soil surface, which subsequently affected soil CO2 and N2O emission. Also, soil N2O emission was affected by N fertilizer rates, where higher N fertilizer rates caused higher soil N2O emission. It was also observed that dry conditions in 2012 decreased soil CO2 and N2O emission across all management practices, due to lower soil moisture and high soil temperatures. The soil CO2 and N2O emission were affected by corn cob residue left after removal, where areas with excessive amounts of corn cob residue on soil surface showed greater CO2 and N2O emission rates than clean areas. In the corn cob residue bale study, findings suggest that plant growth and development are not greatly impacted by the presence of corn cob residue left after bale removal from the site. It was observed that a minimum amount of corn cob residue was left on the soil surface after bales removal. In general, ERI, extended plant leaf heights, plant population, vegetative growth stages, above-ground biomass, and grain yield for clean and left corn cob residue treatments were slightly lower than control where no corn cob residue bales were placed. Over the study period no changes were observed in organic C and N concentrations of the above-ground biomass and grain. Nonetheless, corn cob residue bale storage on the field showed some changes in the SOC and STN contents at different soil depths. In general, changes in SOC and STN contents were similar across all corn cob residue treatments within each soil depth. However, at the top 7.5 cm soil depth greater SOC and STN content were observed compared to lower soil depths across all corn cob residue treatments. Also, soil pH at the top 7.5 cm soil depth was lower than that at lower soil depths across all corn cob residue treatments. Soil MBC concentration was also monitored during the corn cob residue bales study, where in general no corn cob residue treatment effect on MBC was observed within each soil sampling period for both years. However, greater MBC values were observed in the fall for both years across all corn cob residue treatments than early spring. The increase in MBC concentrations can be due to increase in organic matter and its decomposition when left on the soil surface after harvest and removal of corn cob residue bales. At the ENW site physical properties were affected by the storage of corn cob residue bales, where soil macro-aggregates stability and associated C content across all corn cob residue treatments showed a decline by the end of the experiment. While an increase for those parameters associated with micro-aggregates was observed, changes in ρb were mostly found at the top 7.5 cm soil depth across all corn cob residue treatments which are consistent with the increase in SPR values at the same depth. The greatest SPR values are observed in areas where corn cob residue bales were stored. The most effective practices in mitigating corn cob residue effects on plant growth and development, soil physical and chemical properties, and soil CO2 and N2O emission are adequate control of field machinery traffic for corn cob residue removal and corn cob residue cleaning. Field machinery for removal of loose and baled corn cob residue should be conducted under suitable conditions (i.e. dry soil condition) to minimize soil compaction during the removal of corn cob residue left on the soil surface. Such management practices can reduce corn cob residue effects on corn productivity and soil health (physical, biological, and chemical optimum functions). Also, an adequate application of N fertilizer rates will help reduce corn cob residue effect of N-immobilization and subsequent effects on plant development.</p

Dificultades en la adquisición de destrezas en la lecto escritura en el quinto año de Educación General Básica de la Unidad Educativa José Gorelik de la parroquia San Joaquín, cantón Cuenca en el periodo 2015-2016

Este trabajo investigativo, tiene como propósito identificar las principales dificultades para adquirir destrezas de la lectoescritura, determinando las causas y consecuencias, el trabajo pluridocente, la falta de motivación e importancia por la lectura, los hábitos incorrectos al leer o escribir, el desinterés por la aplicación de los debidos procesos tanto en la lectura como en la escritura.This investigative work, has as purpose to identify the main difficulties to acquire dexterities of the lecto it notarizes, determining the causes and consequences, the work pluridocente, the motivation lack and importance for the reading, the incorrect habits when reading or to write, the indifference for the application of the due processes as much in the reading as in the writing

Nitrous oxide emissions from agricultural soils challenge climate sustainability in the US Corn Belt

Agricultural landscapes are the largest source of anthropogenic nitrous oxide (N2O) emissions, but their specific sources and magnitudes remain contested. In the US Corn Belt, a globally important N2O source, in-field soil emissions were reportedly too small to account for N2O measured in the regional atmosphere, and disproportionately high N2O emissions from intermittent streams have been invoked to explain the discrepancy. We collected three years of high frequency (4-h) measurements across a topographic gradient including a very poorly drained (intermittently flooded) depression and adjacent upland soils. Mean annual N2O emissions from this corn–soybean rotation (7.8 kg N2O-N ha-1 y-1) were similar to a previous regional top-down estimate, regardless of landscape position. Synthesizing other Corn Belt studies, we found mean emissions of 5.6 kg N2O-N ha-1 y-1 from soils with similar drainage to our transect (moderately well-drained to very poorly drained), which collectively comprise 60% of corn–soybean cultivated soils. In contrast, strictly well-drained soils averaged only 2.3 kg N2O-N ha-1 y-1. Our results imply that in-field N2O emissions from soils with moderately to severely impaired drainage are similar to regional mean values, and that N2O emissions from well-drained soils are not representative of the broader Corn Belt. On the basis of carbon-dioxide equivalents, the warming effect of direct N2O emissions from our transect was two-fold greater than optimistic soil carbon gains achievable from agricultural practice changes. Despite the recent focus on soil carbon sequestration, addressing N2O emissions from wet Corn Belt soils may have greater leverage in achieving climate sustainability.This is a manuscript of an article published as Lawrence, Nathaniel C., Carlos G. Tenesaca, Andy VanLoocke, and Steven J. Hall. "Nitrous oxide emissions from agricultural soils challenge climate sustainability in the US Corn Belt." Proceedings of the National Academy of Sciences 118, no. 46 (2021). doi:10.1073/pnas.2112108118. Posted with persmission.</p

Uso de materiales pétreos modificados para mejorar la estructura de vías urbanas en lastre del cantón de Cuenca

Este trabajo contempla el estudio experimental del empleo del aceite usado por el parque automotor de la ciudad, como estabilizante del lastre extraído de la mina municipal de Chocarsi, utilizado por el GAD municipal en el mantenimiento de las vías urbanas no pavimentadas del cantón Cuenca. Los ensayos de suelos realizados fueron: límites de Atterberg, granulometría, Proctor modificado, CBR con y sin adición de aceite usado, el aceite empleado remplaza un porcentaje del volumen óptimo de agua determinado en el ensayo de Proctor modificado. Con los ensayos de laboratorio se pudo determinar que la estabilización de lastre con aceite residual dio resultados positivos reemplazando en el rango del 3% al 4% del volumen de agua óptimo, obtenido en el ensayo de proctor modificado, por aceite residual con una mejora del valor del CBR hasta en un 14.69%. Se realizó una prueba piloto en la calle Beethoven ubicada al sur de la ciudad, en un tramo de 104 x 6.5 metros, que consistió en colocar una capa de 0.1metros de lastre modificado en los primeros 40 metros del tramo y comparar su comportamiento con los últimos 44 metros, en donde se colocó lastre no modificado. Se monitoreó su comportamiento por el lapso de tres meses, mediante densidades de campo, CBRs mediante correlación utilizando el cono dinámico de penetración, nivelación de alineaciones longitudinales y muestro de porcentaje de baches. Se observó que los valores de los CBRs, y de humedad, en el lastre modificado fueron más favorables que en el tramo con lastre convencional; en la nivelación de las alineaciones longitudinales se encontró que en el tramo donde se colocó lastre modificado existió una menor disminución de cotas de la superficie de rodadura, lo que indica un menor desprendimiento de material.This work contemplates the experimental study of the use of the oil used by the city's automotive fleet, as a stabilizer of the ballast extracted from the Chocarsi municipal mine, used by the municipal GAD in the maintenance of unpaved urban roads in the Cuenca canton. The soil tests carried out were: Atterberg limits, granulometry, modified proctor, and CBR with and without the addition of used oil, the oil used replaces a percentage of the optimum volume of water determined in the modified proctor test. With the tests it was possible to determine that the stabilization of ballast with residual oil gave positive results with 3% and 4% in volume of replacement of oil by water, there was an improvement of the CBR value up to 14.69%. A pilot test was carried out on Beethoven Street located to the south of the city, in a section of 104 x 6.5 meters, which consisted of placing a layer of 0.1 meters of modified ballast in the first 40 meters of the section and comparing its behavior with the last 44 meters where unmodified ballast was placed. Their behavior was monitored for a period of three months, using field densities, CBRs by correlation using the dynamic cone of penetration, leveling of longitudinal alignments, and sampling of the percentage of potholes. It was observed that the values of the CBRs, and humidity, in the modified ballast were more favorable than in the section with conventional ballast; in the leveling of the longitudinal alignments, it was found that in the section where modified ballast was placed, there was a smaller decrease in the levels of the rolling surface, which indicates a smaller detachment of material.0009-0000-8192-7948Magíster en Ingeniería en Vialidad y TransportesCuenc