Monitoreo de playas prioritarias

NORMA RAMIREZ SALINAS JUAN LEODEGARIO GARCIA ROJAS (2012, [Documento de trabajo])

Se presentan los resultados obtenidos en la prueba, para Enterococos en agua de mar, llevada a cabo en 37 playas de Campeche, Chiapas, Guerrero, Jalisco, Nayarit y Veracruz.

Control de calidad del agua Análisis bacteriológico Agua de mar Campeche Chiapas Guerrero Jalisco Nayarit Veracruz INGENIERÍA Y TECNOLOGÍA

Estimación de parámetros de infiltración a partir de mediciones de avance de riego por melgas empleando las ecuaciones de Saint-Venant, y Green y Ampt

Heber Saucedo MANUEL ZAVALA TREJO CARLOS FUENTES RUIZ (2016, [Artículo])

Se presenta un método para realizar la estimación de parámetros de infiltración con base en el empleo de las ecuaciones de Saint-Venant para describir el flujo del agua sobre el suelo, y la ecuación de Green y Ampt para representar el flujo del agua en el suelo. La estimación de los parámetros hidrodinámicos de conductividad hidráulica a saturación y presión en el frente de humedad, se realiza aplicando el método Levenberg-Marquardt. El modelo así obtenido, permite el ajuste de los parámetros hidrodinámicos a partir de datos de pruebas de avance de riego por melgas y de la textura del suelo.

Riego por inundación controlada Modelos matemáticos Método Levenberg-Marquardt CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Agroecology can promote climate change adaptation outcomes without compromising yield in smallholder systems

Sieglinde Snapp Yodit Kebede Eva Wollenberg (2023, [Artículo])

A critical question is whether agroecology can promote climate change mitigation and adaptation outcomes without compromising food security. We assessed the outcomes of smallholder agricultural systems and practices in low- and middle-income countries (LMICs) against 35 mitigation, adaptation, and yield indicators by reviewing 50 articles with 77 cases of agroecological treatments relative to a baseline of conventional practices. Crop yields were higher for 63% of cases reporting yields. Crop diversity, income diversity, net income, reduced income variability, nutrient regulation, and reduced pest infestation, indicators of adaptative capacity, were associated with 70% or more of cases. Limited information on climate change mitigation, such as greenhouse gas emissions and carbon sequestration impacts, was available. Overall, the evidence indicates that use of organic nutrient sources, diversifying systems with legumes and integrated pest management lead to climate change adaptation in multiple contexts. Landscape mosaics, biological control (e.g., enhancement of beneficial organisms) and field sanitation measures do not yet have sufficient evidence based on this review. Widespread adoption of agroecological practices and system transformations shows promise to contribute to climate change services and food security in LMICs. Gaps in adaptation and mitigation strategies and areas for policy and research interventions are finally discussed.

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CLIMATE CHANGE CROPS FOOD SUPPLY GAS EMISSIONS GREENHOUSE GASES FARMING SYSTEMS AGROECOLOGY FOOD SECURITY LESS FAVOURED AREAS SMALLHOLDERS YIELDS NUTRIENTS BIOLOGICAL PEST CONTROL CARBON SEQUESTRATION LEGUMES

Weed management and tillage effect on rainfed maize production in three agro-ecologies in Mexico

Simon Fonteyne Abel Jaime Leal González Rausel Ovando Ravi Gopal Singh Nele Verhulst (2022, [Artículo])

Maize (Zea mays L.) is grown in a wide range of agro-ecological environments and production systems across Mexico. Weeds are a major constraint on maize grain yield, but knowledge regarding the best weed management methods is lacking. In many production systems, reducing tillage could lessen land degradation and production costs, but changes in tillage might require changes in weed management. This study evaluated weed dynamics and rainfed maize yield under five weed management treatments (pre-emergence herbicide, post-emergence herbicide, pre-emergence + post-emergence herbicide, manual weed control, and no control) and three tillage methods (conventional, minimum and zero tillage) in three agro-ecologically distinct regions of the state of Oaxaca, Mexico, in 2016 and 2017. In the temperate Mixteca region, weeds reduced maize grain yields by as much as 92% and the long-growing season required post-emergence weed control, which gave significantly higher yields. In the hot, humid Papaloapan region, weeds reduced maize yields up to 63% and pre-emergence weed control resulted in significantly higher yields than treatments with post-emergence control only. In the semi-arid Valles Centrales region, weeds reduced maize yields by as much as 65%, but weed management was not always effective in increasing maize yield or net profitability. The most effective weed management treatments tended to be similar for the three tillage systems at each site, although weed pressure and the potential yield reduction by weeds tended to be higher under zero tillage than minimum or conventional tillage. No single best option for weed management was found across sites or tillage systems. More research, in which non-chemical methods should not be overlooked, is thus needed to determine the most effective weed management methods for the diverse maize production systems across Mexico.

Corn Integrated Weed Management Manual Weed Control CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA MAIZE WEED CONTROL MINIMUM TILLAGE ZERO TILLAGE

Does access to improved grain storage technology increase farmers' welfare? Experimental evidence from maize farming in Ethiopia

Hugo De Groote Bart Minten (2024, [Artículo])

Seasonal price variability for cereals is two to three times higher in Africa than on the international reference market. Seasonality is even more pronounced when access to appropriate storage and opportunities for price arbitrage are limited. As smallholder farmers typically sell their production after harvest, when prices are low, this leads to lower incomes as well as higher food insecurity during the lean season, when prices are high. One solution to reduce seasonal stress is the use of improved storage technologies. Using data from a randomised controlled trial, in a major maize-growing region of Western Ethiopia, we study the impact of hermetic bags, a technology that protects stored grain against insect pests, so that the grain can be stored longer. Despite considerable price seasonality—maize prices in the lean season are 36% higher than after harvesting—we find no evidence that hermetic bags improve welfare, except that access to these bags allowed for a marginally longer storage period of maize intended for sale by 2 weeks. But this did not translate into measurable welfare gains as we found no changes in any of our welfare outcome indicators. This ‘near-null’ effect is due to the fact that maize storage losses in our study region are relatively lower than previous studies suggested—around 10% of the quantity stored—likely because of the widespread use of an alternative to protect maize during storage, for example a cheap but highly toxic fumigant. These findings are important for policies that seek to promote improved storage technologies in these settings.

Hermetic Storage Randomised Controlled Trial CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA STORAGE PILOT FARMS SEASONALITY WELFARE MAIZE

Forest proximity positively affects natural enemy mediated control of fall armyworm in Southern Africa

Frédéric Baudron Terence Sunderland (2022, [Artículo])

Insectivorous Birds Bat Predation Maize Cultivation CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA FALL ARMYWORMS BIOLOGICAL PEST CONTROL INSECTIVOROUS ANIMALS MAIZE PREDATOR PREY RELATIONS

PROPUESTA DE MANEJO DE LA PESQUERÍA EMERGENTE DE MERLUZA DEL PACÍFICO NORTE Merluccius productus EN EL GOLFO DE ULLOA, BAJA CALIFORNIA SUR

PABLO MORA ZAMACONA (2023, [Tesis de doctorado])

"La merluza del Pacífico Merluccius productus se distribuye desde Alaska hasta el sur de México, con una población particular descrita al sur de la península de Baja California conocida como merluza enana, de la que poco se sabe. Dicha población actualmente no es pescada comercialmente, por lo que representa un recurso con potencial de explotación. Las pesquerías potenciales y emergentes crean desafíos y oportunidades para los administradores pesqueros que necesitan tomar decisiones sobre cómo gestionar de forma sostenible una pesquería previa a su inicio. Este trabajo propone y analiza posibles medidas alternativas de gestión pesquera para esta potencial pesquería, bajo incertidumbre biológica y de mercado. Debido al desconocimiento de diversos aspectos de la biología del recurso primeramente se analizó el crecimiento individual del stock y posteriormente se realizó un análisis bioeconómico de la potencial pesquería.

Para el análisis del crecimiento individual se utilizó un total de 240 otolitos y datos de longitud patrón de 932 especímenes muestreados de mayo a diciembre de 2015. La formación anual de incrementos en los otolitos se verificó mediante la relación de incremento marginal y el análisis de borde. La edad se estimó a partir de recuentos de anillos en secciones sagitales de otolitos y el crecimiento se analizó mediante un enfoque de inferencia multimodelo. Se consideraron los modelos de crecimiento de von Bertalanffy (VBGM), VBGM generalizado, Gompertz, Logístico y Johnson, los cuales se ajustaron a conjuntos de datos de talla a la edad observados y retrocalculados agrupados por sexo. Según el criterio de información de Akaike, el VBGM generalizado fue el más apropiado para las hembras (L∞= 31.36 cm, k= 0.15 cm año-1), mientras que el VBGM proporcionó el mejor ajuste para los machos (L∞= 25.35 cm, k= 0.28 cm año-1).

El análisis bioeconómico de alternativas de manejo para una potencial pesquería de merluza enana indicó que una nueva pesquería de dicho stock podría ser biológicamente sostenible y económicamente rentable, bajo un conjunto de estrategias de gestión y reglas de control. Se recomienda un acceso limitado con bajo esfuerzo pesquero ya que resulta más redituable por barco y biológicamente precautorio, considerando la alta incertidumbre asociada con la explotación de una población virgen..."

"The Pacific hake Merluccius productus is distributed from Alaska to southern Mexico, with a particular population described south of the Baja California peninsula known as dwarf hake, about which little is known. This population is not currently commercially fished; hence it represents a resource with potential for exploitation. Potential and emerging fisheries create challenges and opportunities for fishery managers who need to make decisions about how to sustainably manage a fishery prior to its initiation. This work proposes and analyzes possible alternative fishery management measures for this potential fishery, under biological and market uncertainty. Due to the lack of knowledge of various aspects of the biology of the resource, the individual growth of the stock was first analyzed and subsequently a bioeconomic analysis of the potential fishery was carried out.

A total of 240 otoliths and standard-length data from 932 specimens sampled from May to December 2015 were used for the analysis of individual growth. The annual formation of otolith increments was verified using the marginal increment analysis and the edge analysis. Age was estimated from annuli counts in sagittal sections of otoliths and growth was analyzed using a multi-model inference approach. The von Bertalanffy growth models (VBGM), generalized VBGM, Gompertz, Logistic and Johnson growth models were considered, which were fitted to observed and back calculated length-at-age data sets grouped by sex. According to Akaike's information criterion, the generalized VBGM was the most appropriate for females (L∞= 31.36 cm, k= 0.15 cm year-1), while the VBGM provided the best fit for males (L∞= 25.35 cm, k= 0.28 cm year-1).

The bioeconomic analysis of management alternatives for a potential dwarf hake fishery indicated that a new fishery for said stock could be biologically sustainable and economically profitable, under a set of management strategies and control rules. Limited access with low fishing effort is recommended as it is more profitable by boat and biologically precautionary, considering the high uncertainty associated with the exploitation of an unfished stock. Despite the combination of high fishing costs and low prices, the fishery could still be profitable in the long term, although there is risk of overexploitation if high fishing effort is allowed..."

Merluza enana, stock no explotado, crecimiento individual, análisis bioeconómico, pesquería potencial Dwarf hake, unexploited stock, individual growth, bioeconomic analysis, potential fishery CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS PECES Y FAUNA SILVESTRE REGLAMENTACIÓN Y CONTROL REGLAMENTACIÓN Y CONTROL

Diseño de riego por melgas empleando las ecuaciones de Saint-Venant, y Green y Ampt

Heber Saucedo MANUEL ZAVALA TREJO CARLOS FUENTES RUIZ (2015, [Artículo])

Se presenta un método de diseño de riego por melgas basado en la aplicación de un modelo que emplea las ecuaciones de Saint-Venant, para describir el flujo del agua sobre el suelo, y la ecuación de Green y Ampt, para representar el flujo del agua en el suelo. La principal ventaja del modelo presentado es el poco tiempo de cómputo que requiere para su aplicación, en comparación con el necesario para ejecutar un modelo hidrodinámico completo reportado en la literatura, mismo que emplea las ecuaciones de Saint-Venant para el flujo del agua sobre el suelo, acopladas internamente con la ecuación de Richards, que permite modelar el flujo del agua en el suelo.

Riego por inundación controlada Modelos matemáticos Gasto óptimo CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

COORDINATED CONTROL OF A 6-DOF ROBOTIC MANIPULATOR EMPLOYING VIRTUAL MODELS OF ITS ACTUATORS

Jessica Villalobos (2023, [Tesis de doctorado])

"This study proposes a scheme that combines the model reference control with the internal model control to impose a first-order behavior on the speed control system of direct current motors. This scheme is used as the internal loop to control the position of a model to use it as the reference for the physical motor.

This work also presents an inverse kinematic solution for the UR5 and algorithms to choose angles that do not lead to singularities. These algorithms can be used in independent joint control schemes such as the one proposed in this document."

Internal model control Model reference control Independent joint control Direct current motor UR5 manipulator Inverse kinematics INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS OTRAS ESPECIALIDADES TECNOLÓGICAS OTRAS OTRAS

Sustainable maize intensification through site-specific nutrient management advice: Experimental evidence from Nigeria

Miet Maertens Oyakhilomen Oyinbo Tahirou Abdoulaye Jordan Chamberlin (2023, [Artículo])

There is growing evidence on the impacts of site-specific nutrient management (SSNM) from Asia. The evidence for Sub-Saharan Africa (SSA), where SSNM developments are more recent and where conditions concerning soil fertility and fertilizer use differ importantly from those in Asia, is extremely scarce. We evaluate a SSNM advisory tool that allows extension agents to generate fertilizer recommendations tailored to the specific situation of an individual farmer’s field, using a three-year randomized controlled trial with 792 smallholder farmers in the maize belt of northern Nigeria. Two treatment arms were implemented: T1 and T2 both provide SSNM information on nutrient use and management, but T2 provides additional information on maize price distributions and the associated variability of expected returns to fertilizer use. We estimate average and heterogenous intent-to-treat effects on agronomic, economic and environmental plot-level outcomes. We find that T1 and T2 lead to substantial increases (up to 116%) in the adoption of good fertilizer management practices and T2 leads to incremental increases (up to 18%) in nutrient application rates, yields and revenues. Both treatments improve low levels of nutrient use efficiency and reduce high levels of greenhouse gas emission intensity, after two years of treatment. Our findings underscore the possibility of a more gradual and sustainable intensification of smallholder agriculture in SSA, as compared with the Asian Green Revolution, through increased fertilizer use accompanied by improved fertilizer management.

Randomized Controlled Trial CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA TECHNOLOGY ADOPTION AGRICULTURAL EXTENSION GREEN REVOLUTION FERTILIZERS GREENHOUSE GAS EMISSIONS