Texto español e ínglés Proceeding of the International Workshop on Soil Erosion Processes on Stee... more Texto español e ínglés Proceeding of the International Workshop on Soil Erosion Processes on Steep Lands Evaluation and Modelling, Mérida, Venezuela May 16-20, 1993 Incluye bibliografía
A B S T R A C T Visual field assessments have already been tested for ‘temperate’ soils, but ther... more A B S T R A C T Visual field assessments have already been tested for ‘temperate’ soils, but there is scant information about their applicability to ‘tropical’ soils. This survey contributes to the validation of the visual field assessments by comparing the performance of three of such methods on ‘tropical’ soils. This study was conducted across six different soils with contrasting soil type and land use, in the central-northern part of Venezuela between November 2011 and January 2012. Scores provided by the soil quality scoring procedure (SQSP), the visual evaluation of soil structure (VESS), and the visual soil assessment (VSA), as well as soil physical properties were measured to assess the soil’s structural quality. All methods showed that soil structural quality was unfavourable on a loamy soil (Alfisol) with continuous cereal growth, conventional tillage and low soil organic carbon (SOC), as well as on a silty clay soil (Alfisol) under natural vegetation and cattle production. Where SQSP scores ranged between 1 (extremely firm) and 2 (firm), VESS scores ranged from 4 (compact) to 5 (very compact), and VSA scores were between 0 (poor) and 0.5 (moderately poor). The sandy clay loam (Ultisol) and clay loam (Mollisol) soils under no-tillage and with high SOC had the best soil quality. In our ‘tropical’ Venezuelan soils there was also high correlation (P < 0.01) between the visual assessment scores and soil physical properties such as bulk density (BD), porosity, SOC, and saturated hydraulic conductivity (Ksat), as has been reported for ‘temperate’ soils. A visual poor condition of soil structure corresponded to BD values higher than 1.4 Mg m � 3 , porosity lower than 0.5 m 3 m � 3 , SOC below 25 g kg � 1 , and Ksat (log) values under 0.5 cm h � 1 . In those cases where the rooting system could not be evaluated because of fallow, VSA and VESS appeared to be the most appropriate methods for assessing the soil structure. The rating of the indicator ‘number of earthworms’ should be adjusted for ‘tropical’ soils; this shall improve the accuracy of the VSA method. These methods were capable of distinguishing the different soil structural quality, and are therefore suitable for assessing soil structural quality of ‘tropical’ soils with contrasting soil type and land use.
La falta de información acerca de las características de la erosividad de la lluvia en zonas árid... more La falta de información acerca de las características de la erosividad de la lluvia en zonas áridas y semiáridas ha impedido una evaluación objetiva de su contribución al proceso de erosión de los suelos y a la degradación. La estimación de la erosividad de la lluvia por medio del anál i si s de bandas pluviográficas requiere de una alta inversión de tiempo, lo que implica la necesidad de emplear ecuaciones para la estimación del factor R. El objetivo del estudio fue la estimación de la erosividad de la lluvia (R) mediante el Índice de Fournier Modi f i cado (I FM) desarrol l ado por Arnoldus (1980) y ecuaciones adaptadas al clima de Chile (ICONA, 1988), a partir de información pluviométrica del periodo 1996-2000. Al comparar ambas adaptaciones, los valores generados de R con el IFM resultaron ser mayores a los generados por ICONA, debido a que la erosividad estimada empleando el IFM se calculó como una función de la erosividad de ICONA. En general se observa que ambos métodos prese...
Evaluating runoff and field soil losses by either empirical or physically based erosion models, r... more Evaluating runoff and field soil losses by either empirical or physically based erosion models, requires an understanding and assessment of rainfall characteristics affecting the erosion (sub)processes.In spite of shortcomings and many criticisms on the worldwide use and applicability of RUSLE (Revised Soil Loss Equation), this empirical model still gains worldwide popularity for estimating erosion on a farmfield or micro-catchment scale.One of the limits of the model is the assessment of its climate factor in terms of rain energy and maximum storm intensity, both factors combined in the erosivity factor R, although they not easily available nor easily determinable. Therefore attempts are made to look for more easily determinable rain characteristics such as the monthly precipitation for evaluating the rain aggressiveness (or rain erosivity) on a monthly or yearly basis.As agro-climatological zones have typical rain distributions and rain concentrations, the Modified Fournier Index ...
Con la finalidad de evaluar los efectos del fosfoyeso sobre al-gunas propiedades físicas y químic... more Con la finalidad de evaluar los efectos del fosfoyeso sobre al-gunas propiedades físicas y químicas del suelo, se llevó a ca-bo un ensayo en un suelo franco-arenoso del lote "E" del Cam-po Experimental de la Facultad de Agronomía, UCV, el cual presenta baja relación Ca:Mg, y problemas en la penetración y movimiento del agua en el perfil. Para ello, se utilizaron tres dosis de FOSFOYESO DE PEQUIVEN: 0,5; 1,0 y 5,0 Mg.ha -1 , calculadas en base a mejorar la relación Ca:Mg y superar los problemas de infiltración y mal drenaje, comparando con un testigo, bajo un diseño completamente aleatorio de tres repeti-ciones cada uno. Parcelas de 4 m 2 (2x2 m), constituyeron las unidades experimentales. El Fosfoyeso fue aplicado al voleo superficialmente a las parcelas. Luego se aplicaron 4 riegos con el propósito de distribuir la enmienda en el perfil, reali-zando muestreos de humedad antes y después de cada riego, a fin de evaluar la dinámica de penetración y movimiento de a-gua en el ...
Bananas and plantains (Musa spp.) are among the main staple of millions of people in the world. A... more Bananas and plantains (Musa spp.) are among the main staple of millions of people in the world. Among the main Musaceae diseases that may limit its productivity, Fusarium wilt (FW), caused by Fusarium oxysporum f. sp. cubense (Foc), has been threatening the banana industry for many years, with devastating effects on the economy of many tropical countries, becoming the leading cause of changes in the land use on severely affected areas. In this article, an updated, reflective and practical review of the current state of knowledge concerning the main agro-environmental factors that may affect disease progression and dissemination of this dangerous pathogen has been carried out, focusing on the Venezuelan Musaceae production systems. Environmental variables together with soil management and sustainable cultural practices are important factors affecting FW incidence and severity, excluding that the widespread dissemination of Foc, especially of its highly virulent tropical race 4 (TR4),...
ABSTRACT The distribution and aggressiveness of the precipitation in Los Andes region of Venezuel... more ABSTRACT The distribution and aggressiveness of the precipitation in Los Andes region of Venezuela was evaluated by analyzing monthly precipitation data from 56 meteorological stations. The modified Fournier index (FMI) and precipitation concentration index (PCI) were calculated to assess rain aggressiveness and rain distribution, respectively. The index values were analyzed using univariate and geostatistical analysis adjusting semivariograms to theoretical models. For mapping of the spatial distribution of indices punctual kriging interpolation method was carried out, generating the appropriate file, which was finally edited in ArcView. The results pointed out that the region under study has high and very high rainfall aggressiveness over 70% of the entire territory, while the distribution of rainfall was moderately seasonal. Rainfall aggressiveness, in combination with the predominance of a sloped relief increases the risks of soil degradation, with the annual rainfall ranging from 500 to 3900 mm. In this sense, soil conservation practices should be considered on existing crop production systems in the evaluated region.
Bananas and plantains (Musa spp.) are among the main staple of millions of people in the world. A... more Bananas and plantains (Musa spp.) are among the main staple of millions of people in the world. Among the main Musaceae diseases that may limit its productivity, Fusarium wilt (FW), caused by Fusarium oxysporum f. sp. cubense (Foc), has been threatening the banana industry for many years, with devastating effects on the economy of many tropical countries, becoming the leading cause of changes in the land use on severely affected areas. In this article, an updated, reflective and practical review of the current state of knowledge concerning the main agro-environmental factors that may affect disease progression and dissemination of this dangerous pathogen has been carried out, focusing on the Venezuelan Musaceae production systems. Environmental variables together with soil management and sustainable cultural practices are important factors affecting FW incidence and severity, excluding that the widespread dissemination of Foc, especially of its highly virulent tropical race 4 (TR4),...
In order to select the best uses for each unit of land, using the FAO guidelines for rainfed agri... more In order to select the best uses for each unit of land, using the FAO guidelines for rainfed agriculture, 1076 which constitute the Canton Babahoyo, province of Los Rios, Ecuador were evaluated. For that, we used the geopedological studies, use-coverage and production systems of the canton at 1:25.000 scale, where 80 soil units, and 8 representative types of land utilization types (TUT) were identified. Three of the identified TUT were selected with the following products: rice, bananas and oil palm. Available water, available oxygen, nutrient availability, rooting conditions, conditions affecting germination, excess salts, soil toxicity, ability of tillage, mechanization possibilities and soil loss were selected as relevant land qualities in an environment of geographic information systems (GIS). The physical evaluation of land units was carried out using a multi-criteria valuation as A1 (highly suitable), A2 (moderately suitable), A3 (margi...
El objetivo del presente trabajo fue evaluar el efecto del pastoreo de cerdos, en algunas variabl... more El objetivo del presente trabajo fue evaluar el efecto del pastoreo de cerdos, en algunas variables químicas en un Molisol en Maracay – Venezuela, bajo condiciones isohipertérmicas. Se tomaron muestras de suelos de dos lotes, uno sin cerdos y el otro con cerdos (6 kg de peso vivo por m2). Se consideraron dos profundidades de muestreo (0-5 y 5-10 cm) bajo un diseño factorial 2x2. Se determinó nitrógeno total, nitrógeno amoniacal, nitrógeno nítrico y nitrógeno orgánico. Se realizó la extracción y el fraccionamiento de la materia orgánica del suelo (MOS) y se determinó el carbono orgánico total oxidable, carbono extraíble total (CET), carbono unido a los ácidos húmicos (CAH), los ácidos fúlvicos (CAF) y sustancias no húmicas (CSNH). Además, se realizó el fraccionamiento del fósforo del suelo usando el método de Hedley, extrayéndose las fracciones de fósforo intercambiable en resina (P-membrana), fósforo extraído con bicarbonato de sodio, fósforo inorgánico extraíble en NaOH, fósforo in...
In tropical small islands the application of hydrological modelling is challenged by the scarcity... more In tropical small islands the application of hydrological modelling is challenged by the scarcity of input data. Using in-situ and statistically estimated data, a hydrological model was calibrated and validated for the Upper Navet watershed in Trinidad, a small Caribbean island. The model was built using the soil water assessment tool (SWAT). The sensitivity analysis, calibration and validation were performed in SWAT calibration and uncertainty program (SWAT-CUP) using sequential uncertainty fitting (SUFI-2). The results revealed that for the estimated volume of water flowing into the reservoir (Flow_In) there were six sensitive parameters. To estimate the reservoir volume (Res_Vol), a modification of only the effective hydraulic conductivity was required. The model’s performance for the Flow_In validation showed acceptable values (R2 = 0.91 and NSE = 0.81). The uncertainty analysis indicated lower than recommended values for both the R-factor (0.46) and P-factor (0.31). For Res_Vol...
El uso y manejo de los suelos influencian el contenido de microelementos y su distribución en el ... more El uso y manejo de los suelos influencian el contenido de microelementos y su distribución en el perfil. Con el propósito de evaluar el contenido de microelementos y su distribución en macroagregados y microagregados y su relación con otras características del suelo en el perfil, se llevó a cabo un ensayo en un Entisol ubicado en la Estación Experimental La Iguana, en el estado Guárico, en un sistema de producción maíz-ganado. El maíz fue sembrado usando siembra directa sobre diferentes tipos de coberturas: Vegetación Natural (VN), Centrosema macrocarpum (Cm), Urochloa dyctioneura (Udy) y Urochloa decumbens (Ude), las cuales se utilizaron para pastoreo del ganado ovino, después de la cosecha del maíz. Después del pastoreo, en el segundo ciclo maíz-ganado, se tomaron muestras de suelo (12 puntos por unidad experimental) con la finalidad de determinar: distribución de tamaño de partículas (DTP), carbono orgánico (CO), capacidad de intercambio catiónico (CIC) y hierro (Fe), cobre (Cu),...
Un experimento en invernadero fue conducido para estudiar el efecto del acondicionador organico B... more Un experimento en invernadero fue conducido para estudiar el efecto del acondicionador organico Bocashi (BK), y dos dosis (TC1 y TC2) del acondicionador sintetico Terracottem® (una mezcla de polimeros hidrofilicos, fertilizante, estimuladores de desarrollo radical y cenizas volcanicas), sobre el desarrollo vegetativo y radical de pimenton, Capsicum nahum L., cultivado en un suelo arenoso, donde se aplicaron dos dosis de riego, para mantener el contenido de agua entre 100 y 80% de la capacidad de campo. La eficiencia de agua fue evaluada en funcion de la biomasa aerea, biomasa de raices y del volumen total de agua aplicada en el riego. En todos los tratamientos una mayor cantidad de agua fue requerida para mantener el contenido de humedad a 100% de CC en comparacion a 80% de CC. La mayor produccion de biomasa area se obtuvo con la dosis mas alta de Terracottem (TC1) en ambas condiciones de humedad, no evidenciandose diferencias significativas entre estas. Los tratamientos con Terracottem resultaron en un mayor desarrollo de raices en comparacion al BK aunque la dosis de riego fue mayor. Los menores consumos de agua por unidad de biomasa fueron obtenidos en los tratamientos TC1; BK; TC2; control (SS) y fertilizacion quimica (FQ), no encontrandose diferencias entre las dos dosis de riego, para todos los tratamientos evaluados
In order to evaluate soil susceptibility to physical degradation, four Alfisol soils from the Wes... more In order to evaluate soil susceptibility to physical degradation, four Alfisol soils from the Western and Central Plains were selected and identified as: Barinas, Chaguarama 1, Chaguarama 2, and Chaguarama 3. Research was conducted mainly in field and complementary evaluations were made at the laboratory, based on simple measurements, taking into account the dynamic nature of soil properties. Soil infiltration, bulk density, penetrometer resistance, moisture content, hydraulic conductivity, infiltration through seal, and field capacity were measured in field. Particles' size distribution, wet aggregate size distribution, sealing indices, consistency limits, total porosity, air porosity, cohesion in dry conditions and pore size distribution in each one of the identified soil layers were determined at the laboratory. The evaluation showed that soils have low structural stability and tendency to compactness, due to the particles' size distribution, which affects soil hydrologic...
Texto español e ínglés Proceeding of the International Workshop on Soil Erosion Processes on Stee... more Texto español e ínglés Proceeding of the International Workshop on Soil Erosion Processes on Steep Lands Evaluation and Modelling, Mérida, Venezuela May 16-20, 1993 Incluye bibliografía
A B S T R A C T Visual field assessments have already been tested for ‘temperate’ soils, but ther... more A B S T R A C T Visual field assessments have already been tested for ‘temperate’ soils, but there is scant information about their applicability to ‘tropical’ soils. This survey contributes to the validation of the visual field assessments by comparing the performance of three of such methods on ‘tropical’ soils. This study was conducted across six different soils with contrasting soil type and land use, in the central-northern part of Venezuela between November 2011 and January 2012. Scores provided by the soil quality scoring procedure (SQSP), the visual evaluation of soil structure (VESS), and the visual soil assessment (VSA), as well as soil physical properties were measured to assess the soil’s structural quality. All methods showed that soil structural quality was unfavourable on a loamy soil (Alfisol) with continuous cereal growth, conventional tillage and low soil organic carbon (SOC), as well as on a silty clay soil (Alfisol) under natural vegetation and cattle production. Where SQSP scores ranged between 1 (extremely firm) and 2 (firm), VESS scores ranged from 4 (compact) to 5 (very compact), and VSA scores were between 0 (poor) and 0.5 (moderately poor). The sandy clay loam (Ultisol) and clay loam (Mollisol) soils under no-tillage and with high SOC had the best soil quality. In our ‘tropical’ Venezuelan soils there was also high correlation (P < 0.01) between the visual assessment scores and soil physical properties such as bulk density (BD), porosity, SOC, and saturated hydraulic conductivity (Ksat), as has been reported for ‘temperate’ soils. A visual poor condition of soil structure corresponded to BD values higher than 1.4 Mg m � 3 , porosity lower than 0.5 m 3 m � 3 , SOC below 25 g kg � 1 , and Ksat (log) values under 0.5 cm h � 1 . In those cases where the rooting system could not be evaluated because of fallow, VSA and VESS appeared to be the most appropriate methods for assessing the soil structure. The rating of the indicator ‘number of earthworms’ should be adjusted for ‘tropical’ soils; this shall improve the accuracy of the VSA method. These methods were capable of distinguishing the different soil structural quality, and are therefore suitable for assessing soil structural quality of ‘tropical’ soils with contrasting soil type and land use.
La falta de información acerca de las características de la erosividad de la lluvia en zonas árid... more La falta de información acerca de las características de la erosividad de la lluvia en zonas áridas y semiáridas ha impedido una evaluación objetiva de su contribución al proceso de erosión de los suelos y a la degradación. La estimación de la erosividad de la lluvia por medio del anál i si s de bandas pluviográficas requiere de una alta inversión de tiempo, lo que implica la necesidad de emplear ecuaciones para la estimación del factor R. El objetivo del estudio fue la estimación de la erosividad de la lluvia (R) mediante el Índice de Fournier Modi f i cado (I FM) desarrol l ado por Arnoldus (1980) y ecuaciones adaptadas al clima de Chile (ICONA, 1988), a partir de información pluviométrica del periodo 1996-2000. Al comparar ambas adaptaciones, los valores generados de R con el IFM resultaron ser mayores a los generados por ICONA, debido a que la erosividad estimada empleando el IFM se calculó como una función de la erosividad de ICONA. En general se observa que ambos métodos prese...
Evaluating runoff and field soil losses by either empirical or physically based erosion models, r... more Evaluating runoff and field soil losses by either empirical or physically based erosion models, requires an understanding and assessment of rainfall characteristics affecting the erosion (sub)processes.In spite of shortcomings and many criticisms on the worldwide use and applicability of RUSLE (Revised Soil Loss Equation), this empirical model still gains worldwide popularity for estimating erosion on a farmfield or micro-catchment scale.One of the limits of the model is the assessment of its climate factor in terms of rain energy and maximum storm intensity, both factors combined in the erosivity factor R, although they not easily available nor easily determinable. Therefore attempts are made to look for more easily determinable rain characteristics such as the monthly precipitation for evaluating the rain aggressiveness (or rain erosivity) on a monthly or yearly basis.As agro-climatological zones have typical rain distributions and rain concentrations, the Modified Fournier Index ...
Con la finalidad de evaluar los efectos del fosfoyeso sobre al-gunas propiedades físicas y químic... more Con la finalidad de evaluar los efectos del fosfoyeso sobre al-gunas propiedades físicas y químicas del suelo, se llevó a ca-bo un ensayo en un suelo franco-arenoso del lote "E" del Cam-po Experimental de la Facultad de Agronomía, UCV, el cual presenta baja relación Ca:Mg, y problemas en la penetración y movimiento del agua en el perfil. Para ello, se utilizaron tres dosis de FOSFOYESO DE PEQUIVEN: 0,5; 1,0 y 5,0 Mg.ha -1 , calculadas en base a mejorar la relación Ca:Mg y superar los problemas de infiltración y mal drenaje, comparando con un testigo, bajo un diseño completamente aleatorio de tres repeti-ciones cada uno. Parcelas de 4 m 2 (2x2 m), constituyeron las unidades experimentales. El Fosfoyeso fue aplicado al voleo superficialmente a las parcelas. Luego se aplicaron 4 riegos con el propósito de distribuir la enmienda en el perfil, reali-zando muestreos de humedad antes y después de cada riego, a fin de evaluar la dinámica de penetración y movimiento de a-gua en el ...
Bananas and plantains (Musa spp.) are among the main staple of millions of people in the world. A... more Bananas and plantains (Musa spp.) are among the main staple of millions of people in the world. Among the main Musaceae diseases that may limit its productivity, Fusarium wilt (FW), caused by Fusarium oxysporum f. sp. cubense (Foc), has been threatening the banana industry for many years, with devastating effects on the economy of many tropical countries, becoming the leading cause of changes in the land use on severely affected areas. In this article, an updated, reflective and practical review of the current state of knowledge concerning the main agro-environmental factors that may affect disease progression and dissemination of this dangerous pathogen has been carried out, focusing on the Venezuelan Musaceae production systems. Environmental variables together with soil management and sustainable cultural practices are important factors affecting FW incidence and severity, excluding that the widespread dissemination of Foc, especially of its highly virulent tropical race 4 (TR4),...
ABSTRACT The distribution and aggressiveness of the precipitation in Los Andes region of Venezuel... more ABSTRACT The distribution and aggressiveness of the precipitation in Los Andes region of Venezuela was evaluated by analyzing monthly precipitation data from 56 meteorological stations. The modified Fournier index (FMI) and precipitation concentration index (PCI) were calculated to assess rain aggressiveness and rain distribution, respectively. The index values were analyzed using univariate and geostatistical analysis adjusting semivariograms to theoretical models. For mapping of the spatial distribution of indices punctual kriging interpolation method was carried out, generating the appropriate file, which was finally edited in ArcView. The results pointed out that the region under study has high and very high rainfall aggressiveness over 70% of the entire territory, while the distribution of rainfall was moderately seasonal. Rainfall aggressiveness, in combination with the predominance of a sloped relief increases the risks of soil degradation, with the annual rainfall ranging from 500 to 3900 mm. In this sense, soil conservation practices should be considered on existing crop production systems in the evaluated region.
Bananas and plantains (Musa spp.) are among the main staple of millions of people in the world. A... more Bananas and plantains (Musa spp.) are among the main staple of millions of people in the world. Among the main Musaceae diseases that may limit its productivity, Fusarium wilt (FW), caused by Fusarium oxysporum f. sp. cubense (Foc), has been threatening the banana industry for many years, with devastating effects on the economy of many tropical countries, becoming the leading cause of changes in the land use on severely affected areas. In this article, an updated, reflective and practical review of the current state of knowledge concerning the main agro-environmental factors that may affect disease progression and dissemination of this dangerous pathogen has been carried out, focusing on the Venezuelan Musaceae production systems. Environmental variables together with soil management and sustainable cultural practices are important factors affecting FW incidence and severity, excluding that the widespread dissemination of Foc, especially of its highly virulent tropical race 4 (TR4),...
In order to select the best uses for each unit of land, using the FAO guidelines for rainfed agri... more In order to select the best uses for each unit of land, using the FAO guidelines for rainfed agriculture, 1076 which constitute the Canton Babahoyo, province of Los Rios, Ecuador were evaluated. For that, we used the geopedological studies, use-coverage and production systems of the canton at 1:25.000 scale, where 80 soil units, and 8 representative types of land utilization types (TUT) were identified. Three of the identified TUT were selected with the following products: rice, bananas and oil palm. Available water, available oxygen, nutrient availability, rooting conditions, conditions affecting germination, excess salts, soil toxicity, ability of tillage, mechanization possibilities and soil loss were selected as relevant land qualities in an environment of geographic information systems (GIS). The physical evaluation of land units was carried out using a multi-criteria valuation as A1 (highly suitable), A2 (moderately suitable), A3 (margi...
El objetivo del presente trabajo fue evaluar el efecto del pastoreo de cerdos, en algunas variabl... more El objetivo del presente trabajo fue evaluar el efecto del pastoreo de cerdos, en algunas variables químicas en un Molisol en Maracay – Venezuela, bajo condiciones isohipertérmicas. Se tomaron muestras de suelos de dos lotes, uno sin cerdos y el otro con cerdos (6 kg de peso vivo por m2). Se consideraron dos profundidades de muestreo (0-5 y 5-10 cm) bajo un diseño factorial 2x2. Se determinó nitrógeno total, nitrógeno amoniacal, nitrógeno nítrico y nitrógeno orgánico. Se realizó la extracción y el fraccionamiento de la materia orgánica del suelo (MOS) y se determinó el carbono orgánico total oxidable, carbono extraíble total (CET), carbono unido a los ácidos húmicos (CAH), los ácidos fúlvicos (CAF) y sustancias no húmicas (CSNH). Además, se realizó el fraccionamiento del fósforo del suelo usando el método de Hedley, extrayéndose las fracciones de fósforo intercambiable en resina (P-membrana), fósforo extraído con bicarbonato de sodio, fósforo inorgánico extraíble en NaOH, fósforo in...
In tropical small islands the application of hydrological modelling is challenged by the scarcity... more In tropical small islands the application of hydrological modelling is challenged by the scarcity of input data. Using in-situ and statistically estimated data, a hydrological model was calibrated and validated for the Upper Navet watershed in Trinidad, a small Caribbean island. The model was built using the soil water assessment tool (SWAT). The sensitivity analysis, calibration and validation were performed in SWAT calibration and uncertainty program (SWAT-CUP) using sequential uncertainty fitting (SUFI-2). The results revealed that for the estimated volume of water flowing into the reservoir (Flow_In) there were six sensitive parameters. To estimate the reservoir volume (Res_Vol), a modification of only the effective hydraulic conductivity was required. The model’s performance for the Flow_In validation showed acceptable values (R2 = 0.91 and NSE = 0.81). The uncertainty analysis indicated lower than recommended values for both the R-factor (0.46) and P-factor (0.31). For Res_Vol...
El uso y manejo de los suelos influencian el contenido de microelementos y su distribución en el ... more El uso y manejo de los suelos influencian el contenido de microelementos y su distribución en el perfil. Con el propósito de evaluar el contenido de microelementos y su distribución en macroagregados y microagregados y su relación con otras características del suelo en el perfil, se llevó a cabo un ensayo en un Entisol ubicado en la Estación Experimental La Iguana, en el estado Guárico, en un sistema de producción maíz-ganado. El maíz fue sembrado usando siembra directa sobre diferentes tipos de coberturas: Vegetación Natural (VN), Centrosema macrocarpum (Cm), Urochloa dyctioneura (Udy) y Urochloa decumbens (Ude), las cuales se utilizaron para pastoreo del ganado ovino, después de la cosecha del maíz. Después del pastoreo, en el segundo ciclo maíz-ganado, se tomaron muestras de suelo (12 puntos por unidad experimental) con la finalidad de determinar: distribución de tamaño de partículas (DTP), carbono orgánico (CO), capacidad de intercambio catiónico (CIC) y hierro (Fe), cobre (Cu),...
Un experimento en invernadero fue conducido para estudiar el efecto del acondicionador organico B... more Un experimento en invernadero fue conducido para estudiar el efecto del acondicionador organico Bocashi (BK), y dos dosis (TC1 y TC2) del acondicionador sintetico Terracottem® (una mezcla de polimeros hidrofilicos, fertilizante, estimuladores de desarrollo radical y cenizas volcanicas), sobre el desarrollo vegetativo y radical de pimenton, Capsicum nahum L., cultivado en un suelo arenoso, donde se aplicaron dos dosis de riego, para mantener el contenido de agua entre 100 y 80% de la capacidad de campo. La eficiencia de agua fue evaluada en funcion de la biomasa aerea, biomasa de raices y del volumen total de agua aplicada en el riego. En todos los tratamientos una mayor cantidad de agua fue requerida para mantener el contenido de humedad a 100% de CC en comparacion a 80% de CC. La mayor produccion de biomasa area se obtuvo con la dosis mas alta de Terracottem (TC1) en ambas condiciones de humedad, no evidenciandose diferencias significativas entre estas. Los tratamientos con Terracottem resultaron en un mayor desarrollo de raices en comparacion al BK aunque la dosis de riego fue mayor. Los menores consumos de agua por unidad de biomasa fueron obtenidos en los tratamientos TC1; BK; TC2; control (SS) y fertilizacion quimica (FQ), no encontrandose diferencias entre las dos dosis de riego, para todos los tratamientos evaluados
In order to evaluate soil susceptibility to physical degradation, four Alfisol soils from the Wes... more In order to evaluate soil susceptibility to physical degradation, four Alfisol soils from the Western and Central Plains were selected and identified as: Barinas, Chaguarama 1, Chaguarama 2, and Chaguarama 3. Research was conducted mainly in field and complementary evaluations were made at the laboratory, based on simple measurements, taking into account the dynamic nature of soil properties. Soil infiltration, bulk density, penetrometer resistance, moisture content, hydraulic conductivity, infiltration through seal, and field capacity were measured in field. Particles' size distribution, wet aggregate size distribution, sealing indices, consistency limits, total porosity, air porosity, cohesion in dry conditions and pore size distribution in each one of the identified soil layers were determined at the laboratory. The evaluation showed that soils have low structural stability and tendency to compactness, due to the particles' size distribution, which affects soil hydrologic...
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