The use of wind pumps for greenhouse microirrigation: a case study for tomato in Cuba.

Crop irrigation is a major consumer of energy. Only a few countries are self-sufficient in conventional non-renewable energy sources. Fortunately, there are renewable ones, such as wind, which has experienced recent developments in the area of power generation. Wind pumps can play a vital role in irrigation projects in remote farms. A methodology based on daily estimation balance between water needs and water availability was used to evaluate the feasibility of the most economic windmill irrigation system. For this purpose, several factors were included: three-hourly wind velocity (W3 h, m/s), flow supplied by the wind pump as a function of the elevation height (H, m) and daily greenhouse evapotranspiration as a function of crop planting date. Monthly volumes of water required for irrigation (Dr, m3/ha) and in the water tank (Vd, m3), as well as the monthly irrigable area (Ar, ha), were estimated by cumulative deficit water budgeting taking in account these factors. An example is given illustrating the use of this methodology on tomato crop (Lycopersicon esculentum Mill.) under greenhouse at Ciego de Ávila, Cuba. In this case two different W3 h series (average and low wind year), three different H values and five tomato crop planting dates were considered. The results show that the optimum period of wind-pump driven irrigation is with crop plating in November, recommending a 5 m3 volume tank for cultivated areas around 0.2 ha when using wind pumps operating at 15 m of height elevation.

Long-term foliar persistence and efficacy of spinosad against beet armyworm under greenhouse conditions.

BACKGROUND: The immediate lethality caused by spinosad has been widely studied on Spodoptera exigua (H ¿ ubner). However, long-term effects can also provide valuable information on insecticide toxic action. Here, the persistence of spinosad on Capsicum annuum L. foliage and the lethal and sublethal effects of greenhouse-aged foliar residues of this insecticide on third instars of S. exigua are reported. RESULTS: Foliage was collected at 0, 3, 5, 10, 20, 30, 40 and 50 days after application, and spinosad residues were measured. Residues decreased over time according to first-order kinetics. The average rate constant and half-life of disappearance were 4.44×10?3 and156 daysand5.80×10?3 and120 days for60and120 mg L?1 respectively. Larval mortalitygradually decreased, corresponding to the residues, but was still appreciable (35 and 65% for 60 and 120 mg L?1 respectively) when the larvae were fed with foliage collected 50 days after treatment. Subsequently, pupal development was reduced and varied between 20 and 60% and between 21 and 41% for 60 and 120 mg L?1, respectively, in all ages of leaf residues that were bioassayed. At all time points, the consumption rate by the larvae was reduced between 62 and 84% for both concentrations that were bioassayed. CONCLUSION: It is concluded that, under the present greenhouse conditions, the degradation of spinosad was slower than that reported by other authors in the field, and, because of that, its residues could cause lethal and sublethal effects to S. exigua larvae.

Management of Urban Mobility to Control Climate Change in Cities

The need of decarbonization of urban mobility is one of the main priorities for all countries to achieve greenhouse gas (GHG) emissions reduction targets. In general, the transport modes which have experienced the most growth in recent years tend to be the most polluting. Most efforts have been focused on the vehicle efficiency improvements and vehicle fleet renewal; nevertheless more emphasis should be placed on strategies related to the management of urban mobility and modal share. Research of individual travel which analyzes CO2 emissions and car and public transport share in daily mobility will enable better assessments of the potential of urban mobility measures introduced to limit GHG emissions produced by transport in cities. This paper explores the sustainability impacts of daily mobility in Spain using data from two National Travel Surveys (NTSs) (2000 and 2006) and includes a method by which to estimate the CO2 emissions associated with each journey and each surveyed individual. The results demonstrate that in the 2000 to 2006 period, there has been an increase in daily mobility which has led to a 17% increase in CO2 emissions. When separated by transport mode, cars prove to be the main contributor to that increase, followed by public transport. More focus should be directed toward modal shift strategies which not only take the number of journeys into account but also consider distance. The contributions of this paper have potential applications in the assessment of current and future urban transport policies.

Decarbonization of toll plazas: impact assessment of toll collection system management

Transport climate change impacts have become a worldwide concern. The use of Intelligent Transport Systems (ITS) could contribute to a more effective use of resources in toll road networks. Management of toll plazas is central to the reduction of greenhouse gas (GHG) emissions, as it is there that bottlenecks and congestion occur. This study focuses on management strategies aimed at reducing climate change impacts of toll plazas by managing toll collection systems. These strategies are based on the use of different collection system technologies – Electronic Toll Collection (ETC) and Open Road Tolling (ORT) – and on queue management. The carbon footprint of various toll plazas is determined by a proposed integrated methodology which estimates the carbon dioxide (CO2) emissions of the different operational stages at toll plazas (deceleration, service time, acceleration, and queuing) for the different toll collection systems. To validate the methodology, two main-line toll plazas of a Spanish toll highway were evaluated. The findings reveal that the application of new technologies to toll collection systems is an effective management strategy from an environmental point of view. The case studies revealed that ORT systems lead to savings of up to 70% of CO2 emissions at toll plazas, while ETC systems save 20% comparing to the manual ones. Furthermore, queue management can offer a 16% emissions savings when queue time is reduced by 116 seconds. The integrated methodology provides an efficient environmental management tool for toll plazas. The use of new technologies is the future of the decarbonization of toll plazas.

The use of wind pumps for greenhouse microirrigation: A case study for tomato in Cuba

A methodology based on daily estimation balance between water needs and water availability was used to evaluate the feasibility of the most economic windmill irrigation system. For this purpose, several factors were included: three-hourly wind velocity (W3 h, m/s), flow supplied by the wind pump as a function of the elevation height (H, m) and daily greenhouse evapotranspiration as a function of crop planting date. Monthly volumes of water required for irrigation (Dr, m3/ha) and in the water tank (Vd, m3), as well as the monthly irrigable area (Ar, ha), were estimated by cumulative deficit water budgeting taking in account these factors.

Flujos de gases de efecto invernadero en suelos forestales y agroforestales del centro de la Península Ibérica=Greenhouse gas flows in forest and agroforestry soils in the center of the Iberian Peninsula

Debido a la complejidad de los procesos que controlan el intercambio de gases de carbono (C) y nitrógeno (N) entre el suelo y la atmósfera, en los sistemas forestales y agroforestales, son comprensibles las incógnitas existentes respecto a la estimación de los flujos de los gases de efecto invernadero (GEI) y la capacidad como reservorios de carbono de los suelos, bajo diferentes formas de uso y regímenes de alteración a escala regional y global. Esta escasez de información justifica la necesidad de caracterizar la dinámica de intercambio de GEI en los ecosistemas Mediterráneos, en especial en el contexto actual de cambio climático, y el incremento asociado de temperatura y periodos de sequía, alteración de los patrones de precipitación, y el riesgo de incendios forestales; cuyas consecuencias afectarán tanto a los compartimentos de C y de N del suelo como a la capacidad de secuestro de C de estos ecosistemas. Dentro de este contexto se enmarca la presente tesis doctoral cuyo objetivo ha sido cuantificar y caracterizar los flujos de dióxido de carbono (CO2), de oxido nitroso (N2O) y de metano (CH4), junto con los stocks de C y N, en suelos forestales de Quercus ilex, Quercus pyrenaica y Pinus sylvestris afectados por incendios forestales; así como el estudiar el efecto de la gestión y la cubierta arbórea en la respiración del suelo y los stocks de C y N en una dehesa situada en el centro de la Península Ibérica. De manera que los flujos de CO2, N2O y CH4; y los parámetros físico-químicos y biológicos del suelo fueron estudiados en los diferentes tratamientos y ecosistemas a lo largo del trabajo que se presenta. Los resultados obtenidos muestran la existencia de variaciones temporales y espaciales de la respiración del suelo dentro de una escala geográfica pequeña, controladas principalmente por la temperatura y la humedad del suelo; y por los contenidos de C y N del suelo en un bosque de Pinus sylvestris en la vertiente norte de la Sierra de Guadarrama , en España. El análisis de los efectos de los incendios forestales a largo plazo (6-8 años) revela que las pérdidas anuales de C a través de la respiración del suelo en las zonas quemadas de Quercus ilex, Quercus pyrenaica y Pinus sylvestris fueron 450 gCm-2yr-1, 790 gCm-2yr-1 y 1220 gCm-2yr-1, respectivamente; lo que representa una reducción del 43%, 22% y 11% en comparación con las zonas no quemadas de dichas especies, debido a la destrucción de la masa arbórea. El efecto del fuego también alteró los flujos N2O y CH4 del suelo, de una forma diferente en los distintos ecosistemas y estacionalidades estudiadas. De tal modo, que los suelos quemados mostraron una mayor oxidación del CH4 en las masas de Q. ilex, y una menor oxidación en las de P. sylvestris; además de una disminución de los flujos de N2O en Q. pyrenaica. Los incendios también afectaron los parámetros microclimáticos de los suelos forestales, observándose un incremento de la temperatura del suelo y una disminución de la humedad en los emplazamientos quemados que en los no quemados. Los cationes intercambiables, el pH, el cociente C/N, el contenido en raicillas y la biomasa microbiana también disminuyeron en las zonas quemadas. Aunque el C orgánico del suelo no se alteró de manera significativa, si lo hizo la calidad de la materia orgánica, disminuyendo el carbono lábil y aumentando las formas recalcitrantes lo que se tradujo en menor sensibilidad de la respiración del suelo a la temperatura (valores de Q10) en las zonas quemadas. Los resultados del estudio realizado en la Dehesa muestran que las actividades silvopastorales estudiadas afectaron levemente y de forma no constante a la respiración del suelo y las condiciones microclimáticas del suelo. Se observó una reducción 12% de la respiración del suelo por efecto del pastoreo no intensivo. Sin embargo, se observaron incrementos de 3Mg/ha en los stocks de C y de 0.3 Mg/ha en los stocks de N en los suelos pastoreados en comparación con los no pastoreados. Aunque, no se observó un claro efecto de la labranza sobre la respiración del suelo en nuestro experimento, sin embargo si se observó una disminución de 3.5 Mg/ha en las reservas de C y de 0.3 Mg/ ha en las de N en los suelos labrados comparados con los no labrados. La copa del arbolado influyó de forma positiva tanto en la respiración del suelo, como en los stocks de C y N de los suelos. La humedad del suelo jugó un papel relevante en la sensibilidad de la respiración a la temperatura del suelo. Nuestros resultados ponen de manifiesto la sensibilidad de la respiración del suelo a cambios en la humedad y los parámetros edáficos, y sugieren que la aplicación de modelos estándar para estimar la respiración del suelo en áreas geográficas pequeñas puede no ser adecuada a menos que otros factores sean considerados en combinación con la temperatura del suelo. Además, las diferentes respuestas de los flujos de gases de efecto invernadero a los cambios, años después de la ocurrencia de incendios forestales, destaca la necesidad de incluir estos cambios en las futuras investigaciones de la dinámica del carbono en los ecosistemas mediterráneos. Por otra parte, las respuestas divergentes en los valores de respiración del suelo y en los contenidos de C y N del suelo observados en la dehesa, además de la contribución de la copa de los árboles en los nutrientes del suelo ilustran la importancia de mantener la gestión tradicional aplicada en beneficio de la capacidad de almacenar C en la dehesa estudiada. La información obtenida en este trabajo pretende contribuir a la mejora del conocimiento de la dinámica y el balance de C en los sistemas mediterráneos, además de ayudar a predecir el impacto del cambio climático en el intercambio de C entre los ecosistemas forestales y agroforestales y la atmósfera. ABSTRACT Due to the complexity of the processes that control the exchange of carbon (C) and nitrogen (N) gasses between soils and the atmosphere in forest and agroforestry ecosystems, understandable uncertainties exist as regards the estimation of greenhouse gas (GHG) fluxes and the soil sink capacity at regional and global scale under different forms of land use and disturbance regimes. These uncertainties justify the need to characterize the exchange dynamics of GHG between the atmosphere and soils in Mediterranean terrestrial ecosystems, particularly in the current context of climate change and the associated increase in temperature, drought periods, heavy rainfall events, and increased risk of wildfires, which affect not only the C and N pools but also the soil C sink capacity of these ecosystems. Within this context, the aims of the present thesis were, firstly, to quantify and characterize the fluxes of carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) as well as the C and N stocks in Quercus ilex, Quercus pyrenaica and Pinus sylvestris stands affected by wildfires, and secondly, to study the effects of Quercus ilex canopy and management on both soil respiration and C and N pools in dehesa systems in the center of Iberian Peninsula. Soil CO2, N2O and CH4 fluxes, and soil physical-chemical and biological parameters were studied under the different treatments and ecosystems considered in this study. The results showed seasonal and spatial variations in soil respiration within small geographic areas, mainly controlled by soil temperature and moisture in addition to soil carbon and nitrogen stocks in mixed pine–oak forest ecosystems on the north facing slopes of the Sierra de Guadarrama in Spain. The analysis of long term effects of wildfires (6–8 years) revealed that annual carbon losses through soil respiration from burned sites in Quercus ilex, Quercus pyrenaica and Pinus sylvestris stands were 450 gCm-2yr-1, 790 gCm-2yr-1 and 1220 gCm-2yr-1, respectively; with burned sites emitting 43%, 22% and 11% less in burned as opposed to non-burned sites due the loss of trees. Fire may alter both N2O and CH4 fluxes although the magnitude of such variation depends on the site, soil characteristics and seasonal climatic conditions. The burned sites showed higher CH4 oxidation in Q.ilex stands, and lower oxidation rates in P. sylvestris stands. A reduction in N2O fluxes in Q. pyrenaica stands was detected at burned sites along with changes in soil microclimate; higher soil temperature and lower soil moisture content. Exchangeable cations, the C/N ratio, pH, fine root and microbial biomass were also found to decrease at burned sites. Although the soil organic carbon was not significantly altered, the quality of the organic matter changed, displaying a decrease in labile carbon and a relative increase in refractory forms, leading to lower sensitivity of soil respiration to temperature (Q10 values) at burned sites. The results from the dehesa study show that light grazing and superficial tilling practices used in the studied dehesa system in Spain had a slight but non-consistent impact on soil respiration and soil microclimate over the study period. The reduction in soil respiration in the dehesa system due to the effects of grazing was around 12 %. However, increments of 3Mg/ha in C stocks and 0.3 Mg/ha in N stocks in grazed soils were observed. Although no clear effect of tilling on soil respiration was found, a decrease of 3.5 Mg/ha in C stocks and 0.3 Mg/ha in N stocks was detected for tilled soils. The presence of a tree canopy induced increases in soil respiration, soil C and N stocks, while soil moisture was found to play an important role in soil respiration temperature response. Our results suggest that the use of standard models to estimate soil respiration in small geographical areas may not be adequate unless other factors are considered in addition to soil temperature. Furthermore, the different responses of GHG flux to climatic shifts, many years after the occurrence of wildfire, highlight the need to include these shifts in C dynamics in future research undertaken in Mediterranean ecosystems. Furthermore, divergent responses in soil respiration and soil C and N stocks to grazing or tilling practices in Dehesa systems, and the influence of tree canopy on soil respiration and soil nutrient content, illustrate the importance of maintaining beneficial management practices. Moreover, the carbon sequestration capacity of the Dehesa system studied may be enhanced through improvements in the management applied. It is hoped that the information obtained through this research will contribute towards improving our understanding of the dynamics and balance of C in Mediterranean systems, and help predict the impact of climate change on the exchange of C between forest and agroforestry ecosystems and the atmosphere.

Farm nitrogen balances in six European landscapes as an indicator for nitrogen losses and basis for improved management.

Improved management of nitrogen (N) in agriculture is necessary to achieve a sustainable balance between the production of food and other biomass, and the unwanted effects of N on water pollution, greenhouse gas emissions, biodiversity deterioration and human health. To analyse farm N-losses and the complex interactions within farming systems, efficient methods for identifying emissions hotspots and evaluating mitigation measures are therefore needed. The present paper aims to fill this gap at the farm and landscape scales. Six agricultural landscapes in Poland (PL), the Netherlands (NL), France (FR), Italy (IT), Scotland (UK) and Denmark (DK) were studied, and a common method was developed for undertaking farm inventories and the derivation of farm N balances, N surpluses and for evaluating uncertainty for the 222 farms and 11 440 ha of farmland included in the study. In all landscapes, a large variation in the farm N surplus was found, and thereby a large potential for reductions. The highest average N surpluses were found in the most livestock-intensive landscapes of IT, FR, and NL; on average 202 ± 28, 179 ± 63 and 178 ± 20 kg N ha−1 yr−1, respectively. All landscapes showed hotspots, especially from livestock farms, including a special UK case with large-scale landless poultry farming. Overall, the average N surplus from the land-based UK farms dominated by extensive sheep and cattle grazing was only 31 ± 10 kg N ha−1 yr−1, but was similar to the N surplus of PL and DK (122 ± 20 and 146 ± 55 kg N ha−1 yr−1, respectively) when landless poultry farming was included. We found farm N balances to be a useful indicator for N losses and the potential for improving N management. Significant correlations to N surplus were found, both with ammonia air concentrations and nitrate concentrations in soils and groundwater, measured during the period of N management data collection in the landscapes from 2007–2009. This indicates that farm N surpluses may be used as an independent dataset for validation of measured and modelled N emissions in agricultural landscapes. No significant correlation was found with N measured in surface waters, probably because of spatial and temporal variations in groundwater buffering and biogeochemical reactions affecting N flows from farm to surface waters. A case study of the development in N surplus from the landscape in DK from 1998–2008 showed a 22% reduction related to measures targeted at N emissions from livestock farms. Based on the large differences in N surplus between average N management farms and the most modern and N-efficient farms, it was concluded that additional N-surplus reductions of 25–50%, as compared to the present level, were realistic in all landscapes. The implemented N-surplus method was thus effective for comparing and synthesizing results on farm N emissions and the potentials of mitigation options. It is recommended for use in combination with other methods for the assessment of landscape N emissions and farm N efficiency, including more detailed N source and N sink hotspot mapping, measurements and modelling.

Management of urban mobility to control climate change in cities in Spain

The need to decarbonize urban mobility is one of the main motivations for all countries to achieve reduction targets for greenhouse gas (GHG) emissions. In general, the transport modes that have experienced the most growth in recent years tend to be the most polluting. Most efforts have focused on improvements in vehicle efficiency and on the renewal of vehicle fleets; more emphasis should be placed on strategies related to the management of urban mobility and modal share. Research of individual travel that analyzes carbon dioxide (CO2) emissions and car and public transport share in daily mobility will enable better assessments of the potential of urban mobility measures introduced to limit GHG emissions produced by transport in cities. The climate change impacts of daily mobility in Spain are explored with data from two national travel surveys in 2000 and 2006, and a method for estimating the CO2 emissions associated with each journey and each surveyed individual is provided. The results demonstrate that from 2000 to 2006, daily mobility has increased and has led to a 17% increase in CO2 emissions. When these results are separated by transport mode, cars prove to be the main contributor to that increase, followed by public transport. More focus should be directed toward modal shift strategies, which take into account not only the number of journeys but also the distance traveled. These contributions have potential applications in the assessment of current and future urban transport policies related to low-carbon urban transportation.

Fertilization Management: Assessing New Techniques and Key Interactions to Increase Crop Yields With Less N2O Emissions

El óxido nitroso (N2O) es un potente gas de efecto invernadero (GHG) proveniente mayoritariamente de la fertilización nitrogenada de los suelos agrícolas. Identificar estrategias de manejo de la fertilización que reduzcan estas emisiones sin suponer un descenso de los rendimientos es vital tanto a nivel económico como medioambiental. Con ese propósito, en esta Tesis se han evaluado: (i) estrategias de manejo directo de la fertilización (inhibidores de la nitrificación/ureasa); y (ii) interacciones de los fertilizantes con (1) el manejo del agua, (2) residuos de cosecha y (3) diferentes especies de plantas. Para conseguirlo se llevaron a cabo meta-análisis, incubaciones de laboratorio, ensayos en invernadero y experimentos de campo. Los inhibidores de la nitrificación y de la actividad ureasa se proponen habitualmente como medidas para reducir las pérdidas de nitrógeno (N), por lo que su aplicación estaría asociada al uso eficiente del N por parte de los cultivos (NUE). Sin embargo, su efecto sobre los rendimientos es variable. Con el objetivo de evaluar en una primera fase su efectividad para incrementar el NUE y la productividad de los cultivos, se llevó a cabo un meta-análisis. Los inhibidores de la nitrificación dicyandiamide (DCD) y 3,4-dimetilepyrazol phosphate (DMPP) y el inhibidor de la ureasa N-(n-butyl) thiophosphoric triamide (NBPT) fueron seleccionados para el análisis ya que generalmente son considerados las mejores opciones disponibles comercialmente. Nuestros resultados mostraron que su uso puede ser recomendado con el fin de incrementar tanto el rendimiento del cultivo como el NUE (incremento medio del 7.5% y 12.9%, respectivamente). Sin embargo, se observó que su efectividad depende en gran medida de los factores medioambientales y de manejo de los estudios evaluados. Una mayor respuesta fue encontrada en suelos de textura gruesa, sistemas irrigados y/o en cultivos que reciben altas tasas de fertilizante nitrogenado. En suelos alcalinos (pH ≥ 8), el inhibidor de la ureasa NBPT produjo el mayor efecto. Dado que su uso representa un coste adicional para los agricultores, entender las mejores prácticas que permitan maximizar su efectividad es necesario para posteriormente realizar comparaciones efectivas con otras prácticas que incrementen la productividad de los cultivos y el NUE. En base a los resultados del meta-análisis, se seleccionó el NBPT como un inhibidor con gran potencial. Inicialmente desarrollado para reducir la volatilización de amoniaco (NH3), en los últimos años algunos investigadores han demostrado en estudios de campo un efecto mitigador de este inhibidor sobre las pérdidas de N2O provenientes de suelos fertilizados bajo condiciones de baja humedad del suelo. Dada la alta variabilidad de los experimentos de campo, donde la humedad del suelo cambia rápidamente, ha sido imposible entender mecanísticamente el potencial de los inhibidores de la ureasa (UIs) para reducir emisiones de N2O y su dependencia con respecto al porcentaje de poros llenos de agua del suelo (WFPS). Por lo tanto se realizó una incubación en laboratorio con el propósito de evaluar cuál es el principal mecanismo biótico tras las emisiones de N2O cuando se aplican UIs bajo diferentes condiciones de humedad del suelo (40, 60 y 80% WFPS), y para analizar hasta qué punto el WFPS regula el efecto del inhibidor sobre las emisiones de N2O. Un segundo UI (i.e. PPDA) fue utilizado para comparar el efecto del NBPT con el de otro inhibidor de la ureasa disponible comercialmente; esto nos permitió comprobar si el efecto de NBPT es específico de ese inhibidor o no. Las emisiones de N2O al 40% WFPS fueron despreciables, siendo significativamente más bajas que las de todos los tratamientos fertilizantes al 60 y 80% WFPS. Comparado con la urea sin inhibidor, NBPT+U redujo las emisiones de N2O al 60% WFPS pero no tuvo efecto al 80% WFPS. La aplicación de PPDA incrementó significativamente las emisiones con respecto a la urea al 80% WFPS mientras que no se encontró un efecto significativo al 60% WFPS. Al 80% WFPS la desnitrificación fue la principal fuente de las emisiones de N2O en todos los tratamientos mientras que al 60% tanto la nitrificación como la desnitrificación tuvieron un papel relevante. Estos resultados muestran que un correcto manejo del NBPT puede suponer una estrategia efectiva para mitigar las emisiones de N2O. Con el objetivo de trasladar nuestros resultados de los estudios previos a condiciones de campo reales, se desarrolló un experimento en el que se evaluó la efectividad del NBPT para reducir pérdidas de N y aumentar la productividad durante un cultivo de cebada (Hordeum vulgare L.) en secano Mediterráneo. Se determinó el rendimiento del cultivo, las concentraciones de N mineral del suelo, el carbono orgánico disuelto (DOC), el potencial de desnitrificación, y los flujos de NH3, N2O y óxido nítrico (NO). La adición del inhibidor redujo las emisiones de NH3 durante los 30 días posteriores a la aplicación de urea en un 58% y las emisiones netas de N2O y NO durante los 95 días posteriores a la aplicación de urea en un 86 y 88%, respectivamente. El uso de NBPT también incrementó el rendimiento en grano en un 5% y el consumo de N en un 6%, aunque ninguno de estos incrementos fue estadísticamente significativo. Bajo las condiciones experimentales dadas, estos resultados demuestran el potencial del inhibidor de la ureasa NBPT para mitigar las emisiones de NH3, N2O y NO provenientes de suelos arables fertilizados con urea, mediante la ralentización de la hidrólisis de la urea y posterior liberación de menores concentraciones de NH4 + a la capa superior del suelo. El riego por goteo combinado con la aplicación dividida de fertilizante nitrogenado disuelto en el agua de riego (i.e. fertirriego por goteo) se considera normalmente una práctica eficiente para el uso del agua y de los nutrientes. Algunos de los principales factores (WFPS, NH4 + y NO3 -) que regulan las emisiones de GHGs (i.e. N2O, CO2 y CH4) y NO pueden ser fácilmente manipulados por medio del fertirriego por goteo sin que se generen disminuciones del rendimiento. Con ese propósito se evaluaron opciones de manejo para reducir estas emisiones en un experimento de campo durante un cultivo de melón (Cucumis melo L.). Los tratamientos incluyeron distintas frecuencias de riego (semanal/diario) y tipos de fertilizantes nitrogenados (urea/nitrato cálcico) aplicados por fertirriego. Fertirrigar con urea en lugar de nitrato cálcico aumentó las emisiones de N2O y NO por un factor de 2.4 y 2.9, respectivamente (P < 0.005). El riego diario redujo las emisiones de NO un 42% (P < 0.005) pero aumentó las emisiones de CO2 un 21% (P < 0.05) comparado con el riego semanal. Analizando el Poder de Calentamiento global en base al rendimiento así como los factores de emisión del NO, concluimos que el fertirriego semanal con un fertilizante de tipo nítrico es la mejor opción para combinar productividad agronómica con sostenibilidad medioambiental en este tipo de agroecosistemas. Los suelos agrícolas en las áreas semiáridas Mediterráneas se caracterizan por su bajo contenido en materia orgánica y bajos niveles de fertilidad. La aplicación de residuos de cosecha y/o abonos es una alternativa sostenible y eficiente desde el punto de vista económico para superar este problema. Sin embargo, estas prácticas podrían inducir cambios importantes en las emisiones de N2O de estos agroecosistemas, con impactos adicionales en las emisiones de CO2. En este contexto se llevó a cabo un experimento de campo durante un cultivo de cebada (Hordeum vulgare L.) bajo condiciones Mediterráneas para evaluar el efecto de combinar residuos de cosecha de maíz con distintos inputs de fertilizantes nitrogenados (purín de cerdo y/o urea) en estas emisiones. La incorporación de rastrojo de maíz incrementó las emisiones de N2O durante el periodo experimental un 105%. Sin embargo, las emisiones de NO se redujeron significativamente en las parcelas enmendadas con rastrojo. La sustitución parcial de urea por purín de cerdo redujo las emisiones netas de N2O un 46 y 39%, con y sin incorporación de residuo de cosecha respectivamente. Las emisiones netas de NO se redujeron un 38 y un 17% para estos mismos tratamientos. El ratio molar DOC:NO3 - demostró predecir consistentemente las emisiones de N2O y NO. El efecto principal de la interacción entre el fertilizante nitrogenado y el rastrojo de maíz se dio a los 4-6 meses de su aplicación, generando un aumento del N2O y una disminución del NO. La sustitución de urea por purín de cerdo puede considerarse una buena estrategia de manejo dado que el uso de este residuo orgánico redujo las emisiones de óxidos de N. Los pastos de todo el mundo proveen numerosos servicios ecosistémicos pero también suponen una importante fuente de emisión de N2O, especialmente en respuesta a la deposición de N proveniente del ganado mientras pasta. Para explorar el papel de las plantas como mediadoras de estas emisiones, se analizó si las emisiones de N2O dependen de la riqueza en especies herbáceas y/o de la composición específica de especies, en ausencia y presencia de una deposición de orina. Las hipótesis fueron: 1) las emisiones de N2O tienen una relación negativa con la productividad de las plantas; 2) mezclas de cuatro especies generan menores emisiones que monocultivos (dado que su productividad será mayor); 3) las emisiones son menores en combinaciones de especies con distinta morfología radicular y alta biomasa de raíz; y 4) la identidad de las especies clave para reducir el N2O depende de si hay orina o no. Se establecieron monocultivos y mezclas de dos y cuatro especies comunes en pastos con rasgos funcionales divergentes: Lolium perenne L. (Lp), Festuca arundinacea Schreb. (Fa), Phleum pratense L. (Php) y Poa trivialis L. (Pt), y se cuantificaron las emisiones de N2O durante 42 días. No se encontró relación entre la riqueza en especies y las emisiones de N2O. Sin embargo, estas emisiones fueron significativamente menores en ciertas combinaciones de especies. En ausencia de orina, las comunidades de plantas Fa+Php actuaron como un sumidero de N2O, mientras que los monocultivos de estas especies constituyeron una fuente de N2O. Con aplicación de orina la comunidad Lp+Pt redujo (P < 0.001) las emisiones de N2O un 44% comparado con los monocultivos de Lp. Las reducciones de N2O encontradas en ciertas combinaciones de especies pudieron explicarse por una productividad total mayor y por una complementariedad en la morfología radicular. Este estudio muestra que la composición de especies herbáceas es un componente clave que define las emisiones de N2O de los ecosistemas de pasto. La selección de combinaciones de plantas específicas en base a la deposición de N esperada puede, por lo tanto, ser clave para la mitigación de las emisiones de N2O. ABSTRACT Nitrous oxide (N2O) is a potent greenhouse gas (GHG) directly linked to applications of nitrogen (N) fertilizers to agricultural soils. Identifying mitigation strategies for these emissions based on fertilizer management without incurring in yield penalties is of economic and environmental concern. With that aim, this Thesis evaluated: (i) the use of nitrification and urease inhibitors; and (ii) interactions of N fertilizers with (1) water management, (2) crop residues and (3) plant species richness/identity. Meta-analysis, laboratory incubations, greenhouse mesocosm and field experiments were carried out in order to understand and develop effective mitigation strategies. Nitrification and urease inhibitors are proposed as means to reduce N losses, thereby increasing crop nitrogen use efficiency (NUE). However, their effect on crop yield is variable. A meta-analysis was initially conducted to evaluate their effectiveness at increasing NUE and crop productivity. Commonly used nitrification inhibitors (dicyandiamide (DCD) and 3,4-dimethylepyrazole phosphate (DMPP)) and the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) were selected for analysis as they are generally considered the best available options. Our results show that their use can be recommended in order to increase both crop yields and NUE (grand mean increase of 7.5% and 12.9%, respectively). However, their effectiveness was dependent on the environmental and management factors of the studies evaluated. Larger responses were found in coarse-textured soils, irrigated systems and/or crops receiving high nitrogen fertilizer rates. In alkaline soils (pH ≥ 8), the urease inhibitor NBPT produced the largest effect size. Given that their use represents an additional cost for farmers, understanding the best management practices to maximize their effectiveness is paramount to allow effective comparison with other practices that increase crop productivity and NUE. Based on the meta-analysis results, NBPT was identified as a mitigation option with large potential. Urease inhibitors (UIs) have shown to promote high N use efficiency by reducing ammonia (NH3) volatilization. In the last few years, however, some field researches have shown an effective mitigation of UIs over N2O losses from fertilized soils under conditions of low soil moisture. Given the inherent high variability of field experiments where soil moisture content changes rapidly, it has been impossible to mechanistically understand the potential of UIs to reduce N2O emissions and its dependency on the soil water-filled pore space (WFPS). An incubation experiment was carried out aiming to assess what is the main biotic mechanism behind N2O emission when UIs are applied under different soil moisture conditions (40, 60 and 80% WFPS), and to analyze to what extent the soil WFPS regulates the effect of the inhibitor over N2O emissions. A second UI (i.e. PPDA) was also used aiming to compare the effect of NBPT with that of another commercially available urease inhibitor; this allowed us to see if the effect of NBPT was inhibitor-specific or not. The N2O emissions at 40% WFPS were almost negligible, being significantly lower from all fertilized treatments than that produced at 60 and 80% WFPS. Compared to urea alone, NBPT+U reduced the N2O emissions at 60% WFPS but had no effect at 80% WFPS. The application of PPDA significantly increased the emissions with respect to U at 80% WFPS whereas no significant effect was found at 60% WFPS. At 80% WFPS denitrification was the main source of N2O emissions for all treatments. Both nitrification and denitrification had a determinant role on these emissions at 60% WFPS. These results suggest that adequate management of the UI NBPT can provide, under certain soil conditions, an opportunity for N2O mitigation. We translated our previous results to realistic field conditions by means of a field experiment with a barley crop (Hordeum vulgare L.) under rainfed Mediterranean conditions in which we evaluated the effectiveness of NBPT to reduce N losses and increase crop yields. Crop yield, soil mineral N concentrations, dissolved organic carbon (DOC), denitrification potential, NH3, N2O and nitric oxide (NO) fluxes were measured during the growing season. The inclusion of the inhibitor reduced NH3 emissions in the 30 d following urea application by 58% and net N2O and NO emissions in the 95 d following urea application by 86 and 88%, respectively. NBPT addition also increased grain yield by 5% and N uptake by 6%, although neither increase was statistically significant. Under the experimental conditions presented here, these results demonstrate the potential of the urease inhibitor NBPT in abating NH3, N2O and NO emissions from arable soils fertilized with urea, slowing urea hydrolysis and releasing lower concentrations of NH4 + to the upper soil layer. Drip irrigation combined with split application of N fertilizer dissolved in the irrigation water (i.e. drip fertigation) is commonly considered best management practice for water and nutrient efficiency. Some of the main factors (WFPS, NH4 + and NO3 -) regulating the emissions of GHGs (i.e. N2O, carbon dioxide (CO2) and methane (CH4)) and NO can easily be manipulated by drip fertigation without yield penalties. In this study, we tested management options to reduce these emissions in a field experiment with a melon (Cucumis melo L.) crop. Treatments included drip irrigation frequency (weekly/daily) and type of N fertilizer (urea/calcium nitrate) applied by fertigation. Crop yield, environmental parameters, soil mineral N concentrations, N2O, NO, CH4, and CO2 fluxes were measured during the growing season. Fertigation with urea instead of calcium nitrate increased N2O and NO emissions by a factor of 2.4 and 2.9, respectively (P < 0.005). Daily irrigation reduced NO emissions by 42% (P < 0.005) but increased CO2 emissions by 21% (P < 0.05) compared with weekly irrigation. Based on yield-scaled Global Warming Potential as well as NO emission factors, we conclude that weekly fertigation with a NO3 --based fertilizer is the best option to combine agronomic productivity with environmental sustainability. Agricultural soils in semiarid Mediterranean areas are characterized by low organic matter contents and low fertility levels. Application of crop residues and/or manures as amendments is a cost-effective and sustainable alternative to overcome this problem. However, these management practices may induce important changes in the nitrogen oxide emissions from these agroecosystems, with additional impacts on CO2 emissions. In this context, a field experiment was carried out with a barley (Hordeum vulgare L.) crop under Mediterranean conditions to evaluate the effect of combining maize (Zea mays L.) residues and N fertilizer inputs (organic and/or mineral) on these emissions. Crop yield and N uptake, soil mineral N concentrations, dissolved organic carbon (DOC), denitrification capacity, N2O, NO and CO2 fluxes were measured during the growing season. The incorporation of maize stover increased N2O emissions during the experimental period by c. 105 %. Conversely, NO emissions were significantly reduced in the plots amended with crop residues. The partial substitution of urea by pig slurry reduced net N2O emissions by 46 and 39 %, with and without the incorporation of crop residues respectively. Net emissions of NO were reduced 38 and 17 % for the same treatments. Molar DOC:NO3 - ratio was found to be a robust predictor of N2O and NO fluxes. The main effect of the interaction between crop residue and N fertilizer application occurred in the medium term (4-6 month after application), enhancing N2O emissions and decreasing NO emissions as consequence of residue incorporation. The substitution of urea by pig slurry can be considered a good management strategy since N2O and NO emissions were reduced by the use of the organic residue. Grassland ecosystems worldwide provide many important ecosystem services but they also function as a major source of N2O, especially in response to N deposition by grazing animals. In order to explore the role of plants as mediators of these emissions, we tested whether and how N2O emissions are dependent on grass species richness and/or specific grass species composition in the absence and presence of urine deposition. We hypothesized that: 1) N2O emissions relate negatively to plant productivity; 2) four-species mixtures have lower emissions than monocultures (as they are expected to be more productive); 3) emissions are lowest in combinations of species with diverging root morphology and high root biomass; and 4) the identity of the key species that reduce N2O emissions is dependent on urine deposition. We established monocultures and two- and four-species mixtures of common grass species with diverging functional traits: Lolium perenne L. (Lp), Festuca arundinacea Schreb. (Fa), Phleum pratense L. (Php) and Poa trivialis L. (Pt), and quantified N2O emissions for 42 days. We found no relation between plant species richness and N2O emissions. However, N2O emissions were significantly reduced in specific plant species combinations. In the absence of urine, plant communities of Fa+Php acted as a sink for N2O, whereas the monocultures of these species constituted a N2O source. With urine application Lp+Pt plant communities reduced (P < 0.001) N2O emissions by 44% compared to monocultures of Lp. Reductions in N2O emissions by species mixtures could be explained by total biomass productivity and by complementarity in root morphology. Our study shows that plant species composition is a key component underlying N2O emissions from grassland ecosystems. Selection of specific grass species combinations in the context of the expected nitrogen deposition regimes may therefore provide a key management practice for mitigation of N2O emissions.

Evaluation of the utilization of electric vehicles for building energy management in hotels

Governments are working in new policies to slow down total energy consumption and greenhouse gases (GHG) emissions, promoting the deployment of electric vehicles (EVs) in all countries. In order to facilitate this deployment and help to reduce the final costs of their batteries, additional utilization of EVs when those are parked has been proposed. EVs can be used to minimize the total electricity cost of buildings (named vehicle to building applications, V2B). In this paper an economic evaluation of EVs in the Building Energy Management System is shown. The optimal storage capacity and its equivalent number of EVs are determined. This value is then used for determining the optimal charging schedule to be applied to the batteries. From this schedule, the total expected profit is derived for the case of a real hotel in Spain.

Habitat management for conservation of pollinators in agro-ecosystems of Central Spain

La gestión de hábitat orientada a la conservación de polinizadores en los agro-ecosistemas requiere una selección de especies vegetales atendiendo fundamentalmente a dos criterios: i) el potencial atractivo de sus flores a los polinizadores; y ii) la simplicidad en su manejo agronómico. Además de estas premisas, es necesario considerar la capacidad invasora de estas especies vegetales, debido a que algunas de las más atractivas pueden resultar invasoras en determinados agro-ecosistemas. Por lo tanto, es preciso determinar qué especies vegetales son las más indicadas para ser implementadas en cada agro-ecosistema. En la presente tesis doctoral se plantea la búsqueda de las especies vegetales adecuadas para atraer polinizadores en los agro-ecosistemas del centro de España. En una primera aproximación, se ha evaluado la atracción y expansión espacial (potencial invasivo) de seis plantas perennes de la familia Lamiaceae (aromáticas), elegidas por ser nativas de la región mediterránea. La elección de las especies vegetales se ha llevado a cabo con el fin de crear márgenes funcionales basados en la mezcla de especies vegetales con distintos periodos de floración, de modo que prolonguen la disponibilidad de recursos florales en el tiempo. Tras un primer año dedicado al establecimiento de las especies aromáticas, en los dos años siguientes se ha estudiado la atracción individual y combinada de las especies vegetales sobre los polinizadores, y como ésta se ve afectada por la densidad y la morfología floral, utilizando para ello un diseño experimental en bloques al azar. Los resultados de este estudio han puesto de manifiesto que la morfología floral no tuvo influencia sobre la atracción de las especies vegetales, pero si la densidad floral, puesto que las especies vegetales con mayor densidad de flores (Nepeta tuberosa e Hyssopus officinalis) han mostrado mayor atracción a polinizadores. Cabe destacar que de las seis especies consideradas, dos especies de verano (Melissa officinalis y Thymbra capitata) no han contribuido de forma efectiva a la atracción de la mezcla hacia los polinizadores, mostrando una reducción significativa de este parámetro respecto a las otras especies aromáticas a lo largo del verano. Se ha observado que ninguna de las especies aromáticas evaluadas ha mostrado tendencia invasora a lo largo del estudio. En base a estos resultados, se puede concluir que entre las especies aromáticas estudiadas, N. tuberosa, H. officinalis y Salvia verbenaca son las que ofrecen mayor potencial para ser utilizadas en la conservación de polinizadores. De forma similar al caso de las plantas aromáticas, se ha llevado a cabo una segunda experimentación que incluía doce plantas anuales con floración de primavera, en la que se evaluó la atracción a polinizadores y su comportamiento agronómico. Este estudio con especies herbáceas se ha prolongado durante dos años, utilizando un diseño experimental de bloques aleatorios. Las variables analizadas fueron: el atractivo de las distintas especies vegetales a los polinizadores, su eficiencia de atracción (calculada como una combinación de la duración de la floración y las visitas de insectos), su respuesta a dos tipos de manejo agronómico (cultivo en mezcla frente a monocultivo; laboreo frente a no-laboreo) y su potencial invasivo. Los resultados de esta segunda experimentación han mostrado que las flores de Borago officinalis, Echium plantagineum, Phacelia tanacetifolia y Diplotaxis tenuifolia son atractivas a las abejas, mientras que las flores de Calendula arvensis, Coriandrum sativum, D. tenuifolia y Lobularia maritima son atractivas a los sírfidos. Con independencia del tipo de polinizadores atraídos por cada especie vegetal, se ha observado una mayor eficiencia de atracción en parcelas con monocultivo de D. tenuifolia respecto a las parcelas donde se cultivó una mezcla de especies herbáceas, si bien en estas últimas se observó mayor eficiencia de atracción que en la mayoría de parcelas mono-específicas. Respecto al potencial invasivo de las especies herbáceas, a pesar de que algunas de las más atractivas a polinizadores (P. tanacetifolia and C. arvensis) mostraron tendencia a un comportamiento invasor, su capacidad de auto-reproducción se vio reducida con el laboreo. En resumen, D. tenuifolia es la única especie que presentó una alta eficiencia de atracción a distintos tipos de polinizadores, conjuntamente con una alta capacidad de auto-reproducción pero sin mostrar carácter invasor. Comparando el atractivo de las especies vegetales utilizadas en este estudio sobre los polinizadores, D. tenuifolia es la especie más recomendable para su cultivo orientado a la atracción de polinizadores en agro-ecosistemas en el centro de España. Esta especie herbácea, conocida como rúcula, tiene la ventaja añadida de ser una especie comercializada para el consumo humano. Además de su atractivo a polinizadores, deben considerarse otros aspectos relacionados con la fisiología y el comportamiento de esta especie vegetal en los agro-ecosistemas antes de recomendar su cultivo. Dado que el cultivo en un campo agrícola de una nueva especie vegetal implica unos costes de producción, por ejemplo debidos a la utilización de agua de riego, es necesario evaluar el incremento en dichos costes en función de demanda hídrica específica de esa especie vegetal. Esta variable es especialmente importante en zonas dónde se presentan sequías recurrentes como es el caso del centro y sur-este de la península Ibérica. Este razonamiento ha motivado un estudio sobre los efectos del estrés hídrico por sequía y el estrés por déficit moderado y severo de riego sobre el crecimiento y floración de la especie D. tenuifolia, así como sobre la atracción a polinizadores. Los resultados muestran que tanto el crecimiento y floración de D. tenuifolia como su atracción a polinizadores no se ven afectados si la falta de riego se produce durante un máximo de 4 días. Sin embargo, si la falta de riego se extiende a lo largo de 8 días o más, se observa una reducción significativa en el crecimiento vegetativo, el número de flores abiertas, el área total y el diámetro de dichas flores, así como en el diámetro y longitud del tubo de la corola. Por otro lado, el estudio pone de manifiesto que un déficit hídrico regulado permite una gestión eficiente del agua, la cual, dependiendo del objetivo final del cultivo de D. tenuifolia (para consumo o solo para atracción de polinizadores), puede reducir su consumo entre un 40 y un 70% sin afectar al crecimiento vegetativo y desarrollo floral, y sin reducir significativamente el atractivo a los polinizadores. Finalmente, esta tesis aborda un estudio para determinar cómo afecta el manejo de hábitat a la producción de los cultivos. En concreto, se ha planteado una experimentación que incluye márgenes mono-específicos y márgenes con una mezcla de especies atractivas a polinizadores, con el fin de determinar su efecto sobre la producción del cultivo de cilantro (C. sativum). La elección del cultivo de cilantro se debe a que requiere la polinización de insectos para su reproducción (aunque, en menor medida, puede polinizarse también por el viento), además de la facilidad para estimar su producción en condiciones semi-controladas de campo. El diseño experimental consistía en la siembra de márgenes mono-específicos de D. tenuifolia y márgenes con mezcla de seis especies anuales situados junto al cultivo de cilantro. Estos cultivos con márgenes florales fueron comparados con controles sin margen floral. Además, un segundo grupo de plantas de cilantro situadas junto a todos los tratamientos, cuyas flores fueron cubiertas para evitar su polinización, sirvió como control para evaluar la influencia de los polinizadores en la producción del cultivo. Los resultados muestran que la presencia de cualquiera de los dos tipos de margen floral mejora el peso y el porcentaje de germinación de las semillas de cilantro frente al control sin margen. Si se comparan los dos tipos de margen, se ha observado un mayor número de semillas de cilantro junto al margen con mezcla de especies florales respecto al margen mono-específico, probablemente debido al mayor número visitas de polinizadores. Puesto que el experimento se realizó en condiciones de campo semi-controladas, esto sugiere que las visitas de polinizadores fueron el factor determinante en los resultados. Por otro lado, los resultados apuntan a que la presencia de un margen floral (ya sea mono-especifico o de mezcla) en cultivos de pequeña escala puede aumentar la producción de cilantro en más de un 200%, al tiempo que contribuyen a la conservación de los polinizadores. ABSTRACT Habitat management, aimed to conserve pollinators in agro-ecosystems, requires selection of the most suitable plant species in terms of their attractiveness to pollinators and simplicity of agronomic management. However, since all flowers are not equally attractive to pollinators and many plant species can be weedy or invasive in the particular habitat, it is important to test which plant species are the most appropriate to be implemented in specific agro-ecosystems. For that reason, this PhD dissertation has been focused on determination of the most appropriate aromatic and herbaceous plants for conservation of pollinators in agro-ecosystems of Central Spain. Therefore, in a first approximation, spatial expansion (i.e. potential weediness) and attractiveness to pollinators of six aromatic perennial plants from the Lamiaceae family, native and frequent in the Mediterranean region, were evaluated. Preliminary plant selection was based on designing a functional mixed margins consisting of plants attractive to pollinators and with different blooming periods, in order to extend the availability of floral resources in the field. After a year of vegetative growth, the next two years the plant species were studied in a randomized block design experiment in order to estimate their attractiveness to pollinators in Central Spain and to investigate whether floral morphology and density affect attractiveness to pollinators. The final aim of the study was to evaluate how their phenology and attractiveness to pollinators can affect the functionality of a flowering mixture of these plants. In addition, the spatial expansion, i.e. potential weediness, of the selected plant species was estimated under field conditions, as the final purpose of the studied plants is to be implemented within agro-ecosystems. The results of the experiment showed that floral morphology did not affect the attractiveness of plants to pollinators, but floral density did, as plant species with higher floral density (i.e. Nepeta tuberosa and Hyssopus officinalis) showed significantly higher attractiveness to pollinators. In addition, of six plant species, two summer species (Melissa officinalis and Thymbra capitata) did not efficiently contribute to the attractiveness of the mixture to pollinators, which reduced its attractiveness during the summer period. Finally, as none of the plants showed weedy behaviour under field conditions, the attractive plant species, i.e. N. tuberosa, H. officinalis and the early spring flowering Salvia verbenaca, showed good potential to conserve the pollinators. Similarly, in a second approximation, the attractiveness to pollinators and agronomic behaviour of twelve herbaceous plants blooming in spring were studied. This experiment was conducted over two years in a randomized block design in order to evaluate attractiveness of preselected plant species to pollinators, as well as their attractiveness efficiency (a combination of duration of flowering and insect visitation), their response to two different agronomic management practices (growing in mixed vs. mono-specific plots; tillage vs. no-tillage), and their potential weediness. The results of this experiment showed that the flowers of Borago officinalis, Echium plantagineum, Phacelia tanacetifolia and Diplotaxis tenuifolia were attractive to bees, while Calendula arvensis, Coriandrum sativum, D. tenuifolia and Lobularia maritima were attractive to hoverflies. In addition, floral mixture resulted in lower attractiveness efficiency to pollinators than mono-specific D. tenuifolia, but higher than most of the mono-specific stands. On the other hand, although some of the most attractive plant species (e.g. P. tanacetifolia and C. arvensis) showed potential weediness, their self-seeding was reduced by tillage. After comparing attractiveness efficiency of various herbaceous species to pollinators and their potential weediness, the results indicated that D. tenuifolia showed the highest attractiveness efficiency to pollinators and efficient self-reproduction, making it highly recommended to attract bees and hoverflies in agro-ecosystems of Central Spain. In addition, this plant, commonly known as wild rocket, has a supplementary economic value as a commercialized crop. The implementation of a new floral margin in agro-ecosystems means increased production costs, especially in regions with frequent and long droughts (as it is Central and South-East area of Iberian Peninsula), where the principal agricultural cost is irrigation. Therefore, before recommending D. tenuifolia for sustainable habitat management within agro-ecosystems, it is necessary to study the effect of drought stress and moderate and severe deficit irrigation on its growth, flower development and attractiveness to pollinators. The results of this experiment showed that in greenhouse conditions, potted D. tenuifolia could be without irrigation for 4 days without affecting its growth, flowering and attractiveness to pollinators. However, lack of irrigation for 8 days or longer significantly reduced the vegetative growth, number of open flowers, total floral area, flower diameter, corolla tube diameter and corolla tube length of D. tenuifolia. This study showed that regulated deficit irrigation can improve water use efficiency, and depending on the purpose of growing D. tenuifolia, as a crop or as a beneficial plant to attract pollinators, it can reduce water consumption by 40% to 70% without affecting its vegetative and floral development and without reducing its attractiveness to pollinators. Finally, the following experiment was developed in order to understand how habitat management can influence on the agricultural production. For this purpose, it was evaluated if the vicinity of mixed and mono-specific field margins, preselected to conserve pollinators within agro-ecosystems, can improve seed production in coriander (C. sativum). The selection of this plant species for the experiment was based on its necessity for insect pollination for production of seeds (even though some pollen can be transmitted from one flower to another by wind) and the fact that under semi-controlled field conditions established in the field it is possible to estimate its total seed production. Since D. tenuifolia is attractive for both bees and hoverflies in Central Spain, the main objective of this experiment was to estimate the impact of two different types of field margins, i.e. mono-specific margin with D. tenuifolia and mixed margin with six herbaceous species, on the seed production of potted coriander. For that reason, it was tested: i) if open pollination (control without proximate field margin and treatments with nearby mono-specific and mixed margin) increases the seed production of coriander when compared with no-pollination (covered inflorescences of coriander) under field conditions; ii) if frequency of pollinator visitation to the flowers of coriander was higher in the presence of field margins than in the control without field margin; and iii) if seed production was higher in the presence of field margins than in control plants of coriander without field margin. The results showed that the proximity of both types of floral margins (mixed and mono-specific) improved the seed quality of coriander plants, as seed weight and germination rate were higher than in control plants without field margin. Furthermore, the number of seeds produced was significantly higher in coriander plants grown near mixed margins than near mono-specific margin, probably due to an increase in pollinator visits. Since the experiment was conducted under semi-controlled field conditions, it can be concluded that pollinator visits was the main factor that biased the results, and that presence of both mixed or mono-specific (D. tenuifolia) margins can improve the production of coriander for more than 200% in small-scale gardens and, in addition, conserve the local pollinators.

Management of irrigation frequency and nitrogen fertilization to mitigate GHG and NO emissions from drip-fertigated crops

Drip irrigation combined with split application of fertilizer nitrogen (N) dissolved in the irrigation water (i.e. drip fertigation) is commonly considered best management practice for water and nutrient efficiency. As a consequence, its use is becoming widespread. Some of the main factors (water-filled pore space, NH4+ and NO3−) regulating the emissions of greenhouse gases (i.e. N2O, CO2 and CH4) and NO from agroecosystems can easily be manipulated by drip fertigation without yield penalties. In this study, we tested management options to reduce these emissions in a field experiment with a melon (Cucumis melo L.) crop. Treatments included drip irrigation frequency (weekly/daily) and type of N fertilizer (urea/calcium nitrate) applied by fertigation. Crop yield, environmental parameters, soil mineral N concentrations and fluxes of N2O, NO, CH4 and CO2 were measured during 85 days. Fertigation with urea instead of calcium nitrate increased N2O and NO emissions by a factor of 2.4 and 2.9, respectively (P < 0.005). Daily irrigation reduced NO emissions by 42% (P < 0.005) but increased CO2 emissions by 21% (P < 0.05) compared with weekly irrigation. We found no relation between irrigation frequency and N2O emissions. Based on yield-scaled Global Warming Potential as well as NO cumulative emissions, we conclude that weekly fertigation with a NO3−-based fertilizer is the best option to combine agronomic productivity with environmental sustainability. Our study shows that adequate management of drip fertigation, while contributing to the attainment of water and food security, may provide an opportunity for climate change mitigation.

Towards mitigation of greenhouse gases by small changes in farming practices: understanding local barriers in Spain.

Small changes in agricultural practices have a large potential for reducing greenhouse gas emissions. However, the implementation of such practices at the local level is often limited by a range of barriers. Understanding the barriers is essential for defining effective measures, the actual mitigation potential of the measures, and the policy needs to ensure implementation. Here we evaluate behavioural, cultural, and policy barriers for implementation of mitigation practices at the local level that imply small changes to farmers. The choice of potential mitigation practices relevant to the case study is based on a literature review of previous empirical studies. Two methods that include the stakeholders? involvement (experts and farmers) are undertaken for the prioritization of these potential practices: (a) Multi-criteria analysis (MCA) of the choices of an expert panel and (b) Analysis of barriers to implementation based on a survey of farmers. The MCA considers two future climate scenarios ? current climate and a drier and warmer climate scenario. Results suggest that all potential selected practices are suitable for mitigation considering multiple criteria in both scenarios. Nevertheless, if all the barriers for implementation had the same influence, the preferred mitigation practices in the case study would be changes in fertilization management and use of cover crops. The identification of barriers for the implementation of the practices is based on the econometric analysis of surveys given to farmers. Results show that farmers? environmental concerns, financial incentives and access to technical advice are the main factors that define their barriers to implementation. These results may contribute to develop effective mitigation policy to be included in the 2020 review of the European Union Common Agricultural Policy.

Ammonia and Greenhouse Gases Emission from Slurry Storage with impermeable Cover and Landspreading of Cattle Slurry

Intensive farm systems handle large volume of livestock wastes, resulting in adverse environmental effects, such as gaseous losses into the atmosphere in form of ammonia (NH3) and greenhouse gases (GHG), i.e. methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O). In this study, the manure management continuum of slurry storage with impermeable cover and following cattle slurry band spreading and incorporation to soil was assessed for NH3 and GHG emissions. The experiment was conducted in an outdoor covered storage (flexible bag system) (study I), which collected the slurry produced in 7 dairy cattle farms (2,000 m3 slurry) during 12 days in the northern Spain.

Influence of new integrated pest management strategies on aphidophagous predators in horticultural crops

El 1 de enero de 2014 entró en vigor la Directiva Europea 2009/128/CE sobre uso sostenible de plaguicidas y el Real Decreto 1311/2012 por el cual se traspone dicha normativa comunitaria al ámbito nacional. Estos reglamentos establecen el marco legal por el que las explotaciones agrícolas deben cumplir los principios generales de la Gestión Integrada de Plagas (GIP). Los principios de la GIP dan preferencia a aquellos métodos de control que sean sostenibles y respetuosos con el medio ambiente, dando prioridad al control biológico, al físico y a otros de carácter no químico. Sin embargo, el uso de insecticidas selectivos con los enemigos naturales es necesario en ocasiones para el adecuado manejo de las plagas en cultivos hortícolas. Por ello, el objetivo general de esta Tesis ha sido aportar conocimientos para la mejora del control de plagas en cultivos hortícolas, mediante la integración de estrategias de lucha biológica, física y química. La primera de las líneas de investigación de esta Tesis se centró en el estudio del efecto de la presencia dos depredadores, larvas Chrysoperla carnea y adultos de Adalia bipunctata, en la dispersión del virus de transmisión no persistente Cucumber mosaic virus (CMV) y del virus de transmisión persistente Cucurbit aphid-borne yellows virus (CABYV), transmitidos por el pulgón Aphis gosypii en cultivo de pepino. La tasa de transmisión de CMV fue baja para los dos tiempos de evaluación ensayados (1 y 5 días), debido al limitado movimiento de su vector A. gossypii. Las plantas que resultaron infectadas se localizaron próximas a la fuente de inóculo central y la presencia de ambos enemigos naturales no incrementó significativamente el porcentaje de plantas ocupadas por pulgones ni la tasa de transmisión de CMV. Los patrones de distribución de A. gossypii y de CMV tan solo fueron coincidentes en las proximidades de la planta central infectada en la que se liberaron los insectos. En los ensayos con CABYV, la presencia de C. carnea y de A. bipunctata respectivamente provocó un incremento significativo de la dispersión de A. gossypii tras 14 días, pero no tras 7 días desde la liberación de los insectos. La reducción en el número inicial de pulgones en la planta central infectada con CABYV fue siempre mayor tras la liberación de C. carnea en comparación con A. bipunctata. Sin embargo, la tasa de transmisión de CABYV y su distribución espacial no se vieron significativamente modificadas por la presencia de ninguno de los depredadores, ni tras 7 días ni tras 14 días desde el inicio de los ensayos. Al igual que se estudió el efecto de la presencia de enemigos naturales en el comportamiento de las plagas y en la epidemiología de las virosis que transmiten, en una segunda línea de investigación se evaluó el posible efecto del consumo de pulgones portadores de virus por parte de los enemigos naturales. Este trabajo se llevó a cabo en el Laboratorio de Ecotoxicología del Departamento de Entomología de la Universidade Federal de Lavras (UFLA) (Brasil). En él se evaluó la influencia en los parámetros biológicos del enemigo natural Chrysoperla externa al alimentarse de Myzus persicae contaminados con el virus de transmisión persistente Potato leafroll virus (PLRV). El consumo de M. persicae contaminados con PLRV incrementó significativamente la duración de la fase larvaria, reduciendo también la supervivencia en comparación a otras dos dietas a base de M. persicae no contaminados con el virus y huevos del lepidóptero Ephestia kuehniella. La duración de la fase de pupa de C. externa no difirió significativamente entre las dietas a base de pulgones contaminados con PLRV y pulgones no contaminados, pero ambas fueron menores que con la dieta con huevos de E. kuehniella. Sin embargo, ni la supervivencia en la fase de pupa ni los parámetros reproductivos de los adultos emergidos mostraron diferencias significativas entre las dietas evaluadas. Por el contrario, la supervivencia de los adultos durante los 30 primeros días desde su emergencia sí se vio significativamente afectada por la dieta, siendo al término de este periodo del 54% para aquellos adultos de C. externa que durante su fase larvaria consumieron pulgones con PLRV. Dentro de la GIP, una de las estrategias de carácter físico que se emplean para el control de plagas y enfermedades en cultivos hortícolas protegidos es el uso de plásticos con propiedades fotoselectivas de absorción de la radiación ultravioleta (UV). Por ello, la tercera línea de investigación de la Tesis se centró en el estudio de los efectos directos e indirectos (mediados por la planta) de condiciones especiales de baja radiación UV sobre el crecimiento poblacional del pulgón A. gossypii y los parámetros biológicos del enemigo natural C. carnea, así como sobre las plantas de pepino en las que se liberaron los insectos. Los ensayos se realizaron en jaulones dentro de invernadero, utilizándose en el primero de ellos plantas de pepino sanas, mientras que en el segundo las plantas de pepino fueron previamente infectadas con CABYV para estudiar de qué manera afectaba la incidencia del virus en las mismas condiciones. Las condiciones de baja radiación UV (bajo plástico Térmico Antivirus®) ejercieron un efecto directo en las fases iniciales del cultivo de pepino, promoviendo su crecimiento, mientras que en fases más avanzadas del cultivo indujeron un aumento en el contenido en nitrógeno de las plantas. Las plantas de pepino que fueron sometidas a mayor intensidad de radiación UV (bajo plástico Térmico Blanco®) al inicio del cultivo mostraron un engrosamiento significativo de las paredes de las células epidérmicas del haz de las hojas, así como de la cutícula. El uso del plástico Térmico Antivirus®, utilizado como barrera fotoselectiva para crear condiciones de baja radiación UV, no alteró con respecto al plástico Térmico Blanco® (utilizado como control) el desarrollo poblacional del pulgón A. gossypii ni los parámetros biológicos evaluados en el depredador C. carnea. En el segundo experimento, realizado con plantas infectadas con CABYV, la incidencia de la virosis enmascaró las diferencias encontradas en experimento con plantas sanas, reduciendo aparentemente la influencia de las distintas condiciones de radiación UV. Por último, para el desarrollo de las estrategias de GIP es importante estudiar los posibles efectos secundarios que los plaguicidas pueden tener en los enemigos naturales de las plagas. Es por ello que en la Tesis se evaluaron la toxicidad y los efectos subletales (fecundidad y fertilidad) de flonicamida, flubendiamida, metaflumizona, spirotetramat, sulfoxaflor y deltametrina en los enemigos naturales C. carnea y A. bipunctata. Los efectos secundarios fueron evaluados por contacto residual tanto para larvas como para adultos de ambos enemigos naturales en condiciones de laboratorio. Flonicamida, flubendiamida, metaflumizona y spirotetramat fueron inocuos para larvas de último estadio y adultos de C. carnea y A. bipunctata. Por este motivo, estos insecticidas se presentan como buenos candidatos para ser incorporados dentro de programas de GIP en combinación con estos enemigos naturales para el control de plagas de cultivos hortícolas. Sulfoxaflor fue ligeramente tóxico para adultos de C. carnea y altamente tóxico para larvas de último estadio de A. bipunctata. Para A. bipunctata, sulfoxaflor y deltametrina fueron los compuestos más dañinos. Deltametrina fue también el compuesto más tóxico para larvas y adultos de C. carnea. Por tanto, el uso de deltametrina y sulfoxaflor en programas de GIP debería tomarse en consideración cuando se liberasen cualquiera de estos dos enemigos naturales debido al comportamiento tóxico que mostraron en condiciones de laboratorio. ABSTRACT On 1 January 2014 came into effect the Directive 2009/128/EC of the European Parliament about sustainable use of pesticides and the Royal Decree 1311/2012 that transposes the regulation to the Spanish level. These regulations establish the legal framework that agricultural holdings must adhere to in order to accomplish the general principles of Integrated Pest Management (IPM). The guidelines of IPM give priority to sustainable and eco-friendly pest control techniques, such as biological and physical measures. Nevertheless, the use of pesticides that are selective to natural enemies is sometimes a necessary strategy to implement accurate pest management programs in horticultural protected crops. Therefore, the general objective of this Thesis was to contribute to the improvement of pest management strategies in horticultural crops, by means of the integration of biological, physical and chemical techniques. The first research line of this Thesis was focused on the evaluation of the effects of two aphidophagous predators, Chrysoperla carnea larvae and Adalia bipunctata adults, on the spread of the non-persistently transmitted Cucumber mosaic virus (CMV, Cucumovirus) and the persistently transmitted Cucurbit aphid-borne yellows virus (CABYV, Polerovirus), by the aphid vector Aphis gossypii in a cucumber crop under greenhouse conditions. The CMV transmission rate was generally low, both after 1 and 5 days, due to the limited movement of its aphid vector A. gossypii. Infected plants were mainly located around the central virusinfected source plant, and the percentage of aphid occupation and CMV-infected plants did not differ significantly in absence and presence of natural enemies. The distribution patterns of A. gossypii and CMV were only coincident close to the central plant where insects were released. In the CABYV experiments, the presence of C. carnea larvae and A. bipunctata adults induced significant A. gossypii dispersal after 14 days but not after 7 days. The reduction in the initial aphid population established in the central plant was always higher for C. carnea than for A. bipunctata. Nevertheless, CABYV spread was not significantly modified by the presence of each predator either in the short term (7 days) or in the long term (14 days). Furthermore, the percentage of CABYV-infected plants did not significantly differ when each natural enemy was present in any evaluation period. It is important to evaluate the influence that natural enemies have on pest dynamics and on the spread of viral diseases, but it should be also taken into account the possible effect on the performance of natural enemies when they feed on preys that act as vectors of viruses. Thus, in a second research line developed in the Laboratory of Ecotoxicology, Department of Entomology, of the Universidade Federal de Lavras (UFLA) (Brazil), it was evaluated the performance of Chrysoperla externa under the condition of consuming Myzus persicae acting as vector of Potato leafroll virus (PLRV). The diet composed of PLRV-infected M. persicae significantly increased the length and reduced the survival rate, of the larval period in regard to the other two diets, composed of non-infected M. persicae and Ephestia kuehniella eggs. The lengths of the pupal stage were not significantly different between the aphid diets, but both were significantly shorter than that of E. kuehniella eggs. Neither pupal survival nor reproductive parameters revealed significant differences among the diets. Nevertheless, the adult survival curves during the first 30 days after emergence showed significant differences, reaching at the end of this interval a value of 54% for those C. externa adults fed on PLRVinfected aphids during their larval period. According to the IPM guidelines, one of the physical strategies for the control of pests and diseases in horticultural protected crops is the use of plastic films with photoselective properties that act as ultraviolet (UV) radiation blocking barriers. In this sense, the third research line of the Thesis dealt with the study of the direct and plant-mediated influence of low UV radiation conditions on the performance of the aphid A. gossypii and on the biological parameters of the natural enemy C. carnea, as well as on the cucumber plants where insects were released. The experiments were conducted inside cages under greenhouse conditions, using for the first one healthy cucumber plants, while for the second experiment the cucumber plants were previously infected with CABYV in order to assess the influence of the virus in the same conditions. The low UV radiation conditions (under Térmico Antivirus® plastic film) seemed to exert a direct effect in the early stages of cucumber plants, enhancing their growth, and in an increasing nitrogen content at further developmental stages. The higher UV radiation exposure (under Térmico Blanco® plastic film) in the early stages of the cucumber crop induced the thickening of the adaxial epidermal cell walls and the cuticle of leaves. The use of Térmico Antivirus® plastic film as a photoselective barrier to induce low UV radiation conditions did not modify, in regard to Térmico Blanco® plastic film (used as control), neither the population development of A. gossypii nor the studied biological parameters of the predator C. carnea. In the second experiment, done with CABYV-infected cucumber plants, the incidence of the virus seemed to mask the direct and plant-mediated influence of the different UV radiation conditions. In last term, for the development of IPM strategies it is important to study the potential side effects that pesticides might have on natural enemies. For this reason, in the Thesis were tested the toxicity and sublethal effects (fecundity and fertility) of flonicamid, flubendiamide, metaflumizone, spirotetramat, sulfoxaflor and deltamethrin on the natural enemies C. carnea and A. bipunctata. The side effects of the active ingredients of the insecticides were evaluated with residual contact tests for the larvae and adults of these predators under laboratory conditions. Flonicamid, flubendiamide, metaflumizone and spirotetramat were innocuous to last instar larvae and adults of C. carnea and A. bipunctata. Therefore, these pesticides are promising candidates for being incorporated into IPM programs in combination with these natural enemies for the control of particular greenhouse pests. In contrast, sulfoxaflor was slightly toxic to adults of C. carnea and was highly toxic to last instar larvae of A. bipunctata. For A. bipunctata, sulfoxaflor and deltamethrin were the most damaging compounds. Deltamethrin was also the most toxic compound to larvae and adults of C. carnea. In accordance with this fact, the use of sulfoxaflor and deltamethrin in IPM strategies should be taken into consideration when releasing either of these biological control agents, due to the toxic behavior observed under laboratory conditions.