Effect of reservoir tillage on rainwater harvesting and soil erosion control under a developed rainfall simulator.

Soil erosion is a serious environmental threat in the Mediterranean region due to torrential rainfalls, and it contributes to the degradation of agricultural land. Techniques such as rainwater harvesting may improve soil water storage and increase agricultural productivity, which could result in more effective land usage. Reservoir tillage is an effective system of harvesting rainwater, but it has not been scientifically evaluated like other tillage systems. Its suitability for the conditions in Spain has not been determined. To investigate and quantify water storage from reservoir tillage and how it could be adapted to improve infiltration of harvested rainwater, a laboratory-scale rainfall simulator was developed. Rainfall characteristics, including rainfall intensity, spatial uniformity and raindrop size, confirm that natural rainfall conditions are simulated with sufficient accuracy. The simulator was auto-controlled by a solenoid valve and three pressure nozzles were used to spray water corresponding to five rainfall intensities ranging from 36 to 112 mm h-1 for 3 to 101-year return period with uniformity coefficients between 83 and 94%. In order to assess the reservoir tillage method under surface slopes of 0, 5, and 10%, three soil scooping devices with identical volume were used to make depressions in the following forms: a) truncated square pyramid, b) triangular prism, and c) truncated cone. These depressions were compared to a control soil surface with no depression. For the loam soil used in this study, results show that reservoir tillage was able to reduce soil erosion and surface runoff and significantly increase infiltration. There was significant difference between the depressions and the control. Compared to the control, depression (a) reduced surface runoff by about 61% and the sediment yield concentration by about 79%.

Policy processes and collective action in water reforms: the cases of Nicaragua and Suriname

Las reformas de agua en países en desarrollo suelen llevarse a cabo junto con cambios institucionales más profundos o, incluso, acompañadas de cambios constitucionales o de régimen político. Por lo tanto, los marcos institucionales adaptados a países gobernados sujetos al estado de derecho pueden no ser apropiados para contextos gobernados fundamentalmente, al menos en sus inicios, por instituciones informales o poco maduras. Esta tesis toma las reformas de agua como punto de partida y pretende contribuir a la literatura mediante una serie de análisis empíricos tanto del ámbito general como del plano individual o sujeto personal de la política del agua. En el ámbito general, el foco se pone en los factores que explican el fallo de la acción colectiva en dos contextos diferentes: 1) en la implementación de la nueva Ley de Aguas de Nicaragua y 2) en el mantenimiento y revitalización de las instituciones de riego en Surinam. En el plano del individuo, la investigación se centra en las decisiones de los usuarios de los recursos y analiza el papel crítico de las variables sociales para la gestión de los recursos comunes. Para ello, el método de investigación utilizado es mixto, combinando el análisis de entrevistas, encuestas y experimentos. En el ámbito general, los resultados muestran que las principales barreras para la implementación de la nueva Ley de Aguas de Nicaragua podrían tener su reflejo en el lenguaje de la Ley y, por tanto, en la forma en la que se definen y configuran las instituciones incluidas en dicha Ley. Así, la investigación demuestra que la implementación de políticas no puede ser estudiada o entendida sin tener en cuenta tanto el diseño de la propia política como el marco socio-ecológico en el que se enmarca. El contexto específico de Nicaragua remarca la importancia de considerar tanto las instituciones formales como informales en los procesos de transición política. A pesar de que las reformas de agua requieren plazos largos para su implementación, el hecho de que exista una diferencia entre las reglas tal cual se definen formalmente y las reglas que operan en la realidad merece una mayor consideración en el diseño de políticas basadas fundamentalmente en instituciones formales. En el ámbito de la conducta individual, el análisis de la acción colectiva ofrece una serie de observaciones empíricas interesantes. En el caso de Nicaragua, los resultados indican que la intensidad de las relaciones sociales, el tipo de agentes dispuestos a proporcionar apoyo social y el nivel de confianza en la comunidad son factores que explican de manera significativa la participación en la comunidad. Sin embargo, el hecho de que la gestión colectiva de riego se produzca, en la mayoría de casos, en torno a lazos familiares sugiere que las variables de capital social críticas se definen en gran medida en la esfera familiar, siendo difícil que se extiendan fuera de estos nexos. El análisis experimental de los resultados de un juego de uso de recurso común y contribución al bien público muestra que las preferencias pro-sociales de los individuos y la heterogeneidad del grupo en términos de composición por sexo son factores que explican significativamente los resultados y las decisiones de apropiación a lo largo del juego. En términos del diseño de las políticas, es fundamental tener en cuenta las dinámicas de participación y uso de los recursos comunes de manera que los niveles de cooperación puedan mantenerse en el largo plazo, lo cual, como se observa en el caso de Surinam, no es siempre posible. Finalmente, el caso de Surinam es un ejemplo ilustrativo de los procesos de acción colectiva en economías en transición. El análisis del fallo de la acción colectiva en Surinam muestra que los procesos políticos vinculados al período colonial y de independencia explican en gran medida la falta de claridad en las reglas operacionales y colectivas que gobiernan la gestión de los sistemas de riego y drenaje. Los resultados empíricos sugieren que a pesar de que la acción colectiva para la provisión de los servicios de riego y drenaje estaba bien establecida bajo el régimen colonial, la auto-organización no prosperó en un contexto dependiente del apoyo externo y regido fundamentalmente por reglas diseñadas al nivel competencial del gobierno central. El sistema socio-ecológico que se desarrolló durante la transición post-colonial favoreció, así, la emergencia de comportamientos oportunistas, y posteriormente la inoperancia de los Water Boards (WBs) creados en la época colonial. En este sentido, cualquier intento por revitalizar los WBs y fomentar el desarrollo de la auto-organización de los usuarios necesitará abordar los problemas relacionados con los patrones demográficos, incluyendo la distribución de la tierra, el diseño de instituciones y la falta de confianza en el gobierno, además de las inversiones típicas en infraestructura y sistemas de información hidrológicos. El liderazgo del gobierno, aportando empuje de arriba-abajo, es, además, otro elemento imprescindible en Surinam. ABSTRACT Water reforms in developing countries take place along deeper institutional and even constitutional. Therefore, institutional frameworks that might result in positive outcomes in countries governed by the rule of law might not fit in contexts governed mainly by informal or immature institutions. This thesis takes water reforms as the starting point and aims to contribute to the literature by presenting several conceptual and empirical analyses at both general and individual levels. At the general national level, the focus is on the factors explaining failure of collective action in two different settings: 1) in the implementation of the new Nicaraguan Water Law and 2) in sustaining and revitalizing irrigation institutions in Suriname. At the individual level, the research focuses on the actions of resource users and analyzes the critical role of social variables for common pool resources management. For this purpose, the research presented in this thesis makes use of a mixed-method approach, combining interviews, surveys and experimental methods. Overall, the results show that major barriers for the implementation of the new Nicaraguan Water Law have its reflection on the language of the Law and, therefore, on the way institutions are defined and configured. In this sense, our study shows that implementation cannot fruitfully be studied and understood without taking into account both the policy design and the social-ecological context in which it is framed. The specific setting of Nicaragua highlights the relevance of considering both formal and informal institutions when promoting policy transitions. Despite the unquestionable fact that water reforms implementation needs long periods of time, there is still a gap between the rules on paper and the rules on the ground that deserves further attention when proposing policy changes on the basis of formal institutions. At the level of the individual agent, the analysis of collective action provides a number of interesting empirical insights. In the case of Nicaragua, I found that the intensity of social networks, the type of agents willing to provide social support and the level of trust in the community are all significant factors in explaining collective action at community level. However, the fact that most collective irrigation relies on family ties suggests that critical social capital variables might be defined within the family sphere and making it difficult to go beyond it. Experimental research combining a common pool resource and a public good game in Nicaragua shows that individuals’ pro-social traits and group heterogeneity in terms of sex composition are significant variables in explaining efficiency outcomes and effort decisions along the game. Thus, with regard to policy design, it is fundamental to consider carefully the dynamics of agents' participation and use of common pool resources, for sustaining cooperation in the long term, which, as seen in the case and Surinam, is not always possible. The case of Suriname provides a rich setting for the analysis of collective action in transition economies. The analysis of decay of collective irrigation in Suriname shows that the lack of clear operational and collective choice rules appear to be rooted in deeper political processes that date back to the colonial period. The empirical findings suggest that despite collective action for the provision of irrigation and drainage services was well established during the colonial period, self-organization did not flourish in a context governed by colonial state-crafted rules and mostly dependent on external support. The social-ecological system developed during the post-colonial transition process favored the emergence of opportunistic behavior. In this respect, any attempt to revitalize WBs and support self-organization will need to tackle the problems derived from demographic patterns, including land allocation, institutions design and government distrust, in addition to the typical investments in both physical infrastructure and hydrological information systems. The leadership role of the government, acting as a top-down trigger, is another essential element in Suriname.

Indicators of sustainability of agriculture and livestock in Spain - Indicadores de sostenibilidad de la agricultura y ganadería española

Sustainability is an adjective used to characterize agriculture according to the degree of fulfillment of goals. Those goals are related to agro-ecological, environmental and socio-economic dimensions. Sustainability is a dynamic and temporal character. In absolute terms there is not an ending value because it changes as its dimensions make it. Spain is one of the main agricultural countries of the European Union both in terms of crop land and value of productions. The object of this study is to present a methodology of sustainability account to be incorporated into national statistical and to assess their performance in the course of the years. For that reason the data sources used have been the statistics of the Department of Agriculture and from others database. We presented a set of indicators of sustainability and its evaluation in a time series of at least 30 years. The trend analysis offers the evolution of the numerical values of the indicators in terms of efficiency, physical units used for a unit of product or its value in euros. The analyzed crops have been: wheat, barley, maize, sunflower, sugar beet, wine grape, olive oil, citrus, melon and tomato. Physical indicators were: land, water, energy, erosion, soil organic matter, and carbon balance; socio-economic indicators were: agricultural final production, prices, income, employment and use of fertilizers. In general, all crops increased their productive efficiency, higher in irrigated than on dry land. Spanish agricultural carbon sequestration capacity has multiplied by five in the last seventy years, as a result of the increase in the productivity of crops, in terms of total biomass and the modification of the soil management techniques. Livestock sector presents data of pork, broilers and laying hen. Those showed an improvement in efficiency and economic indicators. Overall we can say that Spanish agriculture and livestock subsector have a tendency towards sustainability, being its main threats extreme meteorological factors and the instability of todays markets.

Modelling of landslides propagation with SPH : effects of rheology and pore water pressure

El estudio desarrollado en este trabajo de tesis se centra en la modelización numérica de la fase de propagación de los deslizamientos rápidos de ladera a través del método sin malla Smoothed Particle Hydrodynamics (SPH). Este método tiene la gran ventaja de permitir el análisis de problemas de grandes deformaciones evitando operaciones costosas de remallado como en el caso de métodos numéricos con mallas tal como el método de los Elementos Finitos. En esta tesis, particular atención viene dada al rol que la reología y la presión de poros desempeñan durante estos eventos. El modelo matemático utilizado se basa en la formulación de Biot-Zienkiewicz v - pw, que representa el comportamiento, expresado en términos de velocidad del esqueleto sólido y presiones de poros, de la mezcla de partículas sólidas en un medio saturado. Las ecuaciones que gobiernan el problema son: • la ecuación de balance de masa de la fase del fluido intersticial, • la ecuación de balance de momento de la fase del fluido intersticial y de la mezcla, • la ecuación constitutiva y • una ecuación cinemática. Debido a sus propiedades geométricas, los deslizamientos de ladera se caracterizan por tener una profundidad muy pequeña frente a su longitud y a su anchura, y, consecuentemente, el modelo matemático mencionado anteriormente se puede simplificar integrando en profundidad las ecuaciones, pasando de un modelo 3D a 2D, el cual presenta una combinación excelente de precisión, sencillez y costes computacionales. El modelo propuesto en este trabajo se diferencia de los modelos integrados en profundidad existentes por incorporar un ulterior modelo capaz de proveer información sobre la presión del fluido intersticial a cada paso computacional de la propagación del deslizamiento. En una manera muy eficaz, la evolución de los perfiles de la presión de poros está numéricamente resuelta a través de un esquema explicito de Diferencias Finitas a cada nodo SPH. Este nuevo enfoque es capaz de tener en cuenta la variación de presión de poros debida a cambios de altura, de consolidación vertical o de cambios en las tensiones totales. Con respecto al comportamiento constitutivo, uno de los problemas principales al modelizar numéricamente deslizamientos rápidos de ladera está en la dificultad de simular con la misma ley constitutiva o reológica la transición de la fase de iniciación, donde el material se comporta como un sólido, a la fase de propagación donde el material se comporta como un fluido. En este trabajo de tesis, se propone un nuevo modelo reológico basado en el modelo viscoplástico de Perzyna, pensando a la viscoplasticidad como a la llave para poder simular tanto la fase de iniciación como la de propagación con el mismo modelo constitutivo. Con el fin de validar el modelo matemático y numérico se reproducen tanto ejemplos de referencia con solución analítica como experimentos de laboratorio. Finalmente, el modelo se aplica a casos reales, con especial atención al caso del deslizamiento de 1966 en Aberfan, mostrando como los resultados obtenidos simulan con éxito estos tipos de riesgos naturales. The study developed in this thesis focuses on the modelling of landslides propagation with the Smoothed Particle Hydrodynamics (SPH) meshless method which has the great advantage of allowing to deal with large deformation problems by avoiding expensive remeshing operations as happens for mesh methods such as, for example, the Finite Element Method. In this thesis, special attention is given to the role played by rheology and pore water pressure during these natural hazards. The mathematical framework used is based on the v - pw Biot-Zienkiewicz formulation, which represents the behaviour, formulated in terms of soil skeleton velocity and pore water pressure, of the mixture of solid particles and pore water in a saturated media. The governing equations are: • the mass balance equation for the pore water phase, • the momentum balance equation for the pore water phase and the mixture, • the constitutive equation and • a kinematic equation. Landslides, due to their shape and geometrical properties, have small depths in comparison with their length or width, therefore, the mathematical model aforementioned can then be simplified by depth integrating the equations, switching from a 3D to a 2D model, which presents an excellent combination of accuracy, computational costs and simplicity. The proposed model differs from previous depth integrated models by including a sub-model able to provide information on pore water pressure profiles at each computational step of the landslide's propagation. In an effective way, the evolution of the pore water pressure profiles is numerically solved through a set of 1D Finite Differences explicit scheme at each SPH node. This new approach is able to take into account the variation of the pore water pressure due to changes of height, vertical consolidation or changes of total stress. Concerning the constitutive behaviour, one of the main issues when modelling fast landslides is the difficulty to simulate with the same constitutive or rheological model the transition from the triggering phase, where the landslide behaves like a solid, to the propagation phase, where the landslide behaves in a fluid-like manner. In this work thesis, a new rheological model is proposed, based on the Perzyna viscoplastic model, thinking of viscoplasticity as the key to close the gap between the triggering and the propagation phase. In order to validate the mathematical model and the numerical approach, benchmarks and laboratory experiments are reproduced and compared to analytical solutions when possible. Finally, applications to real cases are studied, with particular attention paid to the Aberfan flowslide of 1966, showing how the mathematical model accurately and successfully simulate these kind of natural hazards.

Effect of integrated reservoir tillage for in-situ rainwater harvesting and other tillage practices on soil physical properties

There is a need for in-situ soil moisture conservation in arid and semi-arid regions due to insufficient rainfall for agriculture. For this purpose, a combination implement [integrated reservoir tillage system (RT)] comprised of a single-row chisel plow, single-row spike tooth harrow, modified seeder, and spiked roller was developed and compared to the popular tillage practices, viz., minimum tillage (MT) and conventional tillage (CT) in an arid Mediterranean environment in Egypt. The different tillage practices were conducted at tillage depths of 15, 20, and 25 cm and forward speeds of 0.69, 1, 1.25, and 1.53 m s-1. Some soil physical properties, runoff, soil loss, water harvesting efficiency and yield of wheat were evaluated. The different tillage practices caused significant differences in soil physical properties as the RT increased soil infiltration, producing a rate of 48% and 65% higher than that obtained in MT and CT, respectively. The lowest values of runoff and soil loss were recorded under RT as 4.91 mm and 0.65 t ha-1, whereas the highest values were recorded under CT as 11.36 mm and 1.66 t ha-1, respectively. In conclusion, the RT enhanced the infiltration rate, increased water harvesting efficiency, reduced runoff and achieved the highest yield of wheat. The best tillage operating parameters appeared to be at a tillage depth of 20 cm and speed between 1.00 and 1.25 m s-1.

Effect of reservoir tillage on rainwater havesting and soil erosion control under a developed rainfall simulator

Soil erosion is a serious environmental threat in the Mediterranean region due to torrential rainfalls, and it contributes to the degradation of agricultural land. Techniques such as rainwater harvesting may improve soil water storage and increase agricultural productivity, which could result in more effective land usage. Reservoir tillage is an effective system of harvesting rainwater, but it has not been scientifically evaluated like other tillage systems. Its suitability for the conditions in Spain has not been determined. To investigate and quantify water storage from reservoir tillage and how it could be adapted to improve infiltration of harvested rainwater, a laboratory-scale rainfall simulator was developed. Rainfall characteristics, including rainfall intensity, spatial uniformity and raindrop size, confirm that natural rainfall conditions are simulated with sufficient accuracy. The simulator was auto-controlled by a solenoid valve and three pressure nozzles were used to spray water corresponding to five rainfall intensities ranging from 36 to 112 mm h− 1 for 3 to 101-year return period with uniformity coefficients between 83 and 94%. In order to assess the reservoir tillage method under surface slopes of 0, 5, and 10%, three soil scooping devices with identical volume were used to make depressions in the following forms: a) truncated square pyramid, b) triangular prism, and c) truncated cone. These depressions were compared to a control soil surface with no depression. For the loam soil used in this study, results show that reservoir tillage was able to reduce soil erosion and surface runoff and significantly increase infiltration. There was significant difference between the depressions and the control. Compared to the control, depression (a) reduced surface runoff by about 61% and the sediment yield concentration by about 79%.

Testing of crop Models for Accurate Predictions of Evapotranspiration and crop Water Use

All crop models, whether site-specific or global-gridded and regardless of crop, simulate daily crop transpiration and soil evaporation during the crop life cycle, resulting in seasonal crop water use. Modelers use several methods for predicting daily potential evapotranspiration (ET), including FAO-56, Penman-Monteith, Priestley-Taylor, Hargreaves, full energy balance, and transpiration water efficiency. They use extinction equations to partition energy to soil evaporation or transpiration, depending on leaf area index. Most models simulate soil water balance and soil-root water supply for transpiration, and limit transpiration if water uptake is insufficient, and thereafter reduce dry matter production. Comparisons among multiple crop and global gridded models in the Agricultural Model Intercomparison and Improvement Project (AgMIP) show surprisingly large differences in simulated ET and crop water use for the same climatic conditions. Model intercomparisons alone are not enough to know which approaches are correct. There is an urgent need to test these models against field-observed data on ET and crop water use. It is important to test various ET modules/equations in a model platform where other aspects such as soil water balance and rooting are held constant, to avoid compensation caused by other parts of models. The CSM-CROPGRO model in DSSAT already has ET equations for Priestley-Taylor, Penman-FAO-24, Penman-Monteith-FAO-56, and an hourly energy balance approach. In this work, we added transpiration-efficiency modules to DSSAT and AgMaize models and tested the various ET equations against available data on ET, soil water balance, and season-long crop water use of soybean, fababean, maize, and other crops where runoff and deep percolation were known or zero. The different ET modules created considerable differences in predicted ET, growth, and yield.

Application of low cost technology for the management of irrigation in organic orchards

Throughout history, humans have cyclically return to their old traditions such as the organic orchards. Nowadays, these have been integrated into the modern cities and could supply fresh vegetables to the daily food improving human health. Organic orchards grow crops without pesticides and artificial fertilizers thus, they are respectful with the environment and guarantee the food's safety . In modern society, the application of new technology is a must, in this case to obtain an efficient irrigation. In order to monitor a proper irrigation and save water and energy, soil water content probes are used to measure soil water content. Among them, capacitive probes ,monitored with a specific data logger, are typically used. Most of them, specially the data loggers, are expensive and in many cases are not used. In this work, we have applied the open hardware Arduino to build and program a low cost datalogger for the programming of irrigation in an experimental organic orchard. Results showed that the application of such as low cost technology, which is easily available in the market and easy to understand, everyone can built and program its own device helping in managing water resources in organic orchards .

Water and nitrogen footprint in an irrigated crop under mineral and organic fertilization

In order to establish rational nitrogen (N) application and reduce groundwater contamination, a clearer understanding of the N distribution through the growing season and its balance is crucial. Excessive doses of N and/or water applied to fertigated crops involve a substantial risk of aquifer contamination by nitrate; but knowledge of N cycling and availability within the soil could assist in avoiding this excess. In central Spain, the main horticultural fertigated crop is the melon type ?piel de sapo¿ and it is cultivated in vulnerable zones to nitrate pollution (Directive 91/676/CEE). However, until few years ago there were not antecedents related to the optimization of nitrogen fertilization together with irrigation. Water and N footprint are indicators that allow assessing the impact generated by different agricultural practices, so they can be used to improve the management strategies in fertigated crop systems. The water footprint distinguishes between blue water (sources of water applied to the crop, like irrigation and precipitation), green water (water used by the crop and stored in the soil), and it is furthermore possible to quantify the impact of pollution by calculating the grey water, which is defined as the volume of polluted water created from the growing and production of crops. On the other hand, the N footprint considers green N (nitrogen consumed by the crops and stored in the soil), blue N (N available for crop, like N applied with mineral and/or organic fertilizers, N applied with irrigation water and N mineralized during the crop period), whereas grey N is the amount of N-NO3- washed from the soil to the aquifer. All these components are expressed as the ratio between the components of water or N footprint and the yield (m3 t-1 or kg N t-1 respectively). The objetives of this work were to evaluate the impact derivated from the use of different fertilizer practices in a melon crop using water and N footprint.

Agricultural use of organic wastes as source of nitrogen and phosphorus: risks and opportunities

El nitrógeno (N) y el fósforo (P) son nutrientes esenciales en la producción de cultivos. El desarrollo de los fertilizantes de síntesis durante el siglo XX permitió una intensificación de la agricultura y un aumento de las producciones pero a su vez el gran input de nutrientes ha resultado en algunos casos en sistemas poco eficientes incrementando las pérdidas de estos nutrientes al medio ambiente. En el caso del P, este problema se agrava debido a la escasez de reservas de roca fosfórica necesaria para la fabricación de fertilizantes fosfatados. La utilización de residuos orgánicos en agricultura como fuente de N y P es una buena opción de manejo que permite valorizar la gran cantidad de residuos que se generan. Sin embargo, es importante conocer los procesos que se producen en el suelo tras la aplicación de los mismos, ya que influyen en la disponibilidad de nutrientes que pueden ser utilizados por el cultivo así como en las pérdidas de nutrientes de los agrosistemas que pueden ocasionar problemas de contaminación. Aunque la dinámica del N en el suelo ha sido más estudiada que la del P, los problemas importantes de contaminación por nitratos en zonas vulnerables hacen necesaria la evaluación de aquellas prácticas de manejo que pudieran agravar esta situación, y en el caso de los residuos orgánicos, la evaluación de la respuesta agronómica y medioambiental de la aplicación de materiales con un alto contenido en N (como los residuos procedentes de la industria vinícola y alcoholera). En cuanto al P, debido a la mayor complejidad de su ciclo y de las reacciones que ocurren en el suelo, hay un mayor desconocimiento de los factores que influyen en su dinámica en los sistemas suelo-planta, lo que supone nuevas oportunidades de estudio en la evaluación del uso agrícola de los residuos orgánicos. Teniendo en cuenta los conocimientos previos sobre cada nutriente así como las necesidades específicas en el estudio de los mismos, en esta Tesis se han evaluado: (1) el efecto de la aplicación de residuos procedentes de la industria vinícola y alcoholera en la dinámica del N desde el punto de vista agronómico y medioambiental en una zona vulnerable a la contaminación por nitratos; y (2) los factores que influyen en la disponibilidad de P en el suelo tras la aplicación de residuos orgánicos. Para ello se han llevado a cabo incubaciones de laboratorio así como ensayos de campo que permitieran evaluar la dinámica de estos nutrientes en condiciones reales. Las incubaciones de suelo en condiciones controladas de humedad y temperatura para determinar el N mineralizado se utilizan habitualmente para estimar la disponibilidad de N para el cultivo así como el riesgo medioambiental. Por ello se llevó a cabo una incubación en laboratorio para conocer la velocidad de mineralización de N de un compost obtenido a partir de residuos de la industria vinícola y alcoholera, ampliamente distribuida en Castilla-La Mancha, región con problemas importantes de contaminación de acuíferos por nitratos. Se probaron tres dosis crecientes de compost correspondientes a 230, 460 y 690 kg de N total por hectárea que se mezclaron con un suelo franco arcillo arenoso de la zona. La evolución del N mineral en el suelo a lo largo del tiempo se ajustó a un modelo de regresión no lineal, obteniendo valores bajos de N potencialmente mineralizable y bajas contantes de mineralización, lo que indica que se trata de un material resistente a la mineralización y con una lenta liberación de N en el suelo, mineralizándose tan solo 1.61, 1.33 y 1.21% del N total aplicado con cada dosis creciente de compost (para un periodo de seis meses). Por otra parte, la mineralización de N tras la aplicación de este material también se evaluó en condiciones de campo, mediante la elaboración de un balance de N durante dos ciclos de cultivo (2011 y 2012) de melón bajo riego por goteo, cultivo y manejo agrícola muy característicos de la zona de estudio. Las constantes de mineralización obtenidas en el laboratorio se ajustaron a las temperaturas reales en campo para predecir el N mineralizado en campo durante el ciclo de cultivo del melón, sin embargo este modelo generalmente sobreestimaba el N mineralizado observado en campo, por la influencia de otros factores no tenidos en cuenta para obtener esta predicción, como el N acumulado en el suelo, el efecto de la planta o las fluctuaciones de temperatura y humedad. Tanto el ajuste de los datos del laboratorio al modelo de mineralización como las predicciones del mismo fueron mejores cuando se consideraba el efecto de la mezcla suelo-compost que cuando se aislaba el N mineralizado del compost, mostrando la importancia del efecto del suelo en la mineralización del N procedente de residuos orgánicos. Dado que esta zona de estudio ha sido declarada vulnerable a la contaminación por nitratos y cuenta con diferentes unidades hidrológicas protegidas, en el mismo ensayo de campo con melón bajo riego por goteo se evaluó el riesgo de contaminación por nitratos tras la aplicación de diferentes dosis de compost bajo dos regímenes de riego, riego ajustado a las necesidades del cultivo (90 ó 100% de la evapotranspiración del cultivo (ETc)) o riego excedentario (120% ETc). A lo largo del ciclo de cultivo se estimó semanalmente el drenaje mediante la realización de un balance hídrico, así como se tomaron muestras de la solución de suelo y se determinó su concentración de nitratos. Para evaluar el riesgo de contaminación de las aguas subterráneas asociado con estas prácticas, se utilizaron algunos índices medioambientales para determinar la variación en la calidad del agua potable (Índice de Impacto (II)) y en la concentración de nitratos del acuífero (Índice de Impacto Ambiental (EII)). Para combinar parámetros medioambientales con parámetros de producción, se calculó la eficiencia de manejo. Se observó que la aplicación de compost bajo un régimen de riego ajustado no aumentaba el riesgo de contaminación de las aguas subterráneas incluso con la aplicación de la dosis más alta. Sin embargo, la aplicación de grandes cantidades de compost combinada con un riego excedentario supuso un incremento en el N lixiviado a lo largo del ciclo de cultivo, mientras que no se obtuvieron mayores producciones con respecto al riego ajustado. La aplicación de residuos de la industria vinícola y alcoholera como fuente de P fue evaluada en suelos calizos caracterizados por una alta capacidad de retención de P, lo cual en algunos casos limita la disponibilidad de este nutriente. Para ello se llevó a cabo otro ensayo de incubación con dos suelos de diferente textura, con diferente contenido de carbonato cálcico, hierro y con dos niveles de P disponible; a los que se aplicaron diferentes materiales procedentes de estas industrias (con y sin compostaje previo) aportando diferentes cantidades de P. A lo largo del tiempo se analizó el P disponible del suelo (P Olsen) así como el pH y el carbono orgánico disuelto. Al final de la incubación, con el fin de estudiar los cambios producidos por los diferentes residuos en el estado del P del suelo se llevó a cabo un fraccionamiento del P inorgánico del suelo, el cual se separó en P soluble y débilmente enlazado (NaOH-NaCl-P), P soluble en reductores u ocluido en los óxidos de Fe (CBD-P) y P poco soluble precipitado como Ca-P (HCl-P); y se determinó la capacidad de retención de P así como el grado de saturación de este elemento en el suelo. En este ensayo se observó que, dada la naturaleza caliza de los suelos, la influencia de la cantidad de P aplicado con los residuos en el P disponible sólo se producía al comienzo del periodo de incubación, mientras que al final del ensayo el incremento en el P disponible del suelo se igualaba independientemente del P aplicado con cada residuo, aumentando el P retenido en la fracción menos soluble con el aumento del P aplicado. Por el contrario, la aplicación de materiales orgánicos menos estabilizados y con un menor contenido en P, produjo un aumento en las formas de P más lábiles debido a una disolución del P retenido en la fracción menos lábil, lo cual demostró la influencia de la materia orgánica en los procesos que controlan el P disponible en el suelo. La aplicación de residuos aumentó el grado de saturación de P de los suelos, sin embargo los valores obtenidos no superaron los límites establecidos que indican un riesgo de contaminación de las aguas. La influencia de la aplicación de residuos orgánicos en las formas de P inorgánico y orgánico del suelo se estudió además en un suelo ácido de textura areno francosa tras la aplicación en campo a largo plazo de estiércol vacuno y de compost obtenido a partir de biorresiduos, así como la aplicación combinada de compost y un fertilizante mineral (superfosfato tripe), en una rotación de cultivos. En muestras de suelo recogidas 14 años después del establecimiento del experimento en campo, se determinó el P soluble y disponible, la capacidad de adsorción de P, el grado de saturación de P así como diferentes actividades enzimáticas (actividad deshidrogenasa, fosfatasa ácida y fosfatasa alcalina). Las diferentes formas de P orgánico en el suelo se estudiaron mediante una técnica de adición de enzimas con diferentes substratos específicos a extractos de suelo de NaOH-EDTA, midiendo el P hidrolizado durante un periodo de incubación por colorimetría. Las enzimas utilizadas fueron la fosfatasa ácida, la nucleasa y la fitasa las cuales permitieron identificar monoésteres hidrolizables (monoester-like P), diésteres (DNA-like P) e inositol hexaquifosfato (Ins6P-like P). La aplicación a largo plazo de residuos orgánicos aumentó el P disponible del suelo proporcionalmente al P aplicado con cada tipo de fertilización, suponiendo un mayor riesgo de pérdidas de P dado el alto grado de saturación de este suelo. La aplicación de residuos orgánicos aumentó el P orgánico del suelo resistente a la hidrólisis enzimática, sin embargo no influyó en las diferentes formas de P hidrolizable por las enzimas en comparación con las observadas en el suelo sin enmendar. Además, las diferentes formas de P orgánico aplicadas con los residuos orgánicos no se correspondieron con las analizadas en el suelo lo cual demostró que éstas son el resultado de diferentes procesos en el suelo mediados por las plantas, los microorganismos u otros procesos abióticos. En este estudio se encontró una correlación entre el Ins6P-like P y la actividad microbiana (actividad deshidrogenasa) del suelo, lo cual refuerza esta afirmación. Por último, la aplicación de residuos orgánicos como fuente de N y P en la agricultura se evaluó agronómicamente en un escenario real. Se estableció un experimento de campo para evaluar el compost procedente de residuos de bodegas y alcoholeras en el mismo cultivo de melón utilizado en el estudio de la mineralización y lixiviación de N. En este experimento se estudió la aplicación de tres dosis de compost: 1, 2 y 3 kg de compost por metro lineal de plantación correspondientes a 7, 13 y 20 t de compost por hectárea respectivamente; y se estudió el efecto sobre el crecimiento de las plantas, la acumulación de N y P en la planta, así como la producción y calidad del cultivo. La aplicación del compost produjo un ligero incremento en la biomasa vegetal acompañado por una mejora significativa de la producción con respecto a las parcelas no enmendadas, obteniéndose la máxima producción con la aplicación de 2 kg de compost por metro lineal. Aunque los efectos potenciales del N y P fueron parcialmente enmascarados por otras entradas de estos nutrientes en el sistema (alta concentración de nitratos en el agua de riego y ácido fosfórico suministrado por fertirrigación), se observó una mayor acumulación de P uno de los años de estudio que resultó en un aumento en el número de frutos en las parcelas enmendadas. Además, la mayor acumulación de N y P disponible en el suelo al final del ciclo de cultivo indicó el potencial uso de estos materiales como fuente de estos nutrientes. ABSTRACT Nitrogen (N) and phosphorus (P) are essential nutrients in crop production. The development of synthetic fertilizers during the 20th century allowed an intensification of the agriculture increasing crop yields but in turn the great input of nutrients has resulted in some cases in inefficient systems with higher losses to the environment. Regarding P, the scarcity of phosphate rock reserves necessary for the production of phosphate fertilizers aggravates this problem. The use of organic wastes in agriculture as a source of N and P is a good option of management that allows to value the large amount of wastes generated. However, it is important to understand the processes occurring in the soil after application of these materials, as they affect the availability of nutrients that can be used by the crop and the nutrient losses from agricultural systems that can cause problems of contamination. Although soil N dynamic has been more studied than P, the important concern of nitrate pollution in Nitrate Vulnerable Zones requires the evaluation of those management practices that could aggravate this situation, and in the case of organic wastes, the evaluation of the agronomic and environmental response after application of materials with a high N content (such as wastes from winery and distillery industries). On the other hand, due to the complexity of soil P cycle and the reactions that occur in soil, there is less knowledge about the factors that can influence its dynamics in the soil-plant system, which means new opportunities of study regarding the evaluation of the agricultural use of organic wastes. Taking into account the previous knowledge of each nutrient and the specific needs of study, in this Thesis we have evaluated: (1) the effect of the application of wastes from the winery and distillery industries on N dynamics from the agronomic and environmental viewpoint in a vulnerable zone; and (2) the factors that influence P availability in soils after the application of organic wastes. With this purposes, incubations were carried out in laboratory conditions as well as field trials that allow to assess the dynamic of these nutrients in real conditions. Soil incubations under controlled moisture and temperature conditions to determine N mineralization are commonly used to estimate N availability for crops together with the environmental risk. Therefore, a laboratory incubation was conducted in order to determine the N mineralization rate of a compost made from wastes generated in the winery and distillery industries, widely distributed in Castilla-La Mancha, a region with significant problems of aquifers contamination by nitrates. Three increasing doses of compost corresponding to 230, 460 and 690 kg of total N per hectare were mixed with a sandy clay loam soil collected in this area. The evolution of mineral N in soil over time was adjusted to a nonlinear regression model, obtaining low values of potentially mineralizable N and low constants of mineralization, indicating that it is a material resistant to mineralization with a slow release of N, with only 1.61, 1.33 and 1.21% of total N applied being mineralized with each increasing dose of compost (for a period of six months). Furthermore, N mineralization after the application of this material was also evaluated in field conditions by carrying out a N balance during two growing seasons (2011 and 2012) of a melon crop under drip irrigation, a crop and management very characteristic of the area of study. The mineralization constants obtained in the laboratory were adjusted to the actual temperatures observed in the field to predict N mineralized during each growing season, however, this model generally overestimated the N mineralization observed in the field, because of the influence of other factors not taken into account for this prediction, as N accumulated in soil, the plant effect or the fluctuations of temperature and moisture. The fitting of the laboratory data to the model as well as the predictions of N mineralized in the field were better when considering N mineralized from the soil-compost mixture rather than when N mineralized from compost was isolated, underlining the important role of the soil on N mineralization from organic wastes. Since the area of study was declared vulnerable to nitrate pollution and is situated between different protected hydrological units, the risk of nitrate pollution after application of different doses compost was evaluated in the same field trial with melon under two irrigation regimes, irrigation adjusted to the crop needs (90 or 100% of the crop evapotranspiration (ETc)) or excedentary irrigation (120% ETc). Drainage was estimated weekly throughout the growing season by conducting a water balance, samples of the soil solution were taken and the concentration of nitrates was determined. To assess the risk of groundwater contamination associated with these practices, some environmental indices were used to determine the variation in the quality of drinking water (Impact Index (II)) and the nitrates concentration in the groundwater (Environmental Impact Index (EII)). To combine environmental parameters together with yield parameters, the Management Efficiency was calculated. It was observed that the application of compost under irrigation adjusted to the plant needs did not represent a higher risk of groundwater contamination even with the application of the highest doses. However, the application of large amounts of compost combined with an irrigation surplus represented an increase of N leaching during the growing season compared with the unamended plots, while no additional yield with respect to the adjusted irrigation strategy is obtained. The application of wastes derived from the winery and distillery industry as source of P was evaluated in calcareous soils characterized by a high P retention capacity, which in some cases limits the availability of this nutrient. Another incubation experiment was carried out using two soils with different texture, different calcium carbonate and iron contents and two levels of available P; to which different materials from these industries (with and without composting) were applied providing different amounts of P. Soil available P (Olsen P), pH and dissolved organic carbon were analyzed along time. At the end of the incubation, in order to study the changes in soil P status caused by the different residues, a fractionation of soil inorganic P was carried out, which was separated into soluble and weakly bound P (NaOH-NaCl- P), reductant soluble P or occluded in Fe oxides (CBD-P) and P precipitated as poorly soluble Ca-P (HCl-P); and the P retention capacity and degree of P saturation were determined as well. Given the calcareous nature of the soils, the influence of the amount of P applied with the organic wastes in soil available P only occurred at the beginning of the incubation period, while at the end of the trial the increase in soil available P equalled independently of the amount of P applied with each residue, increasing the P retained in the least soluble fraction when increasing P applied. Conversely, the application of less stabilized materials with a lower content of P resulted in an increase in the most labile P forms due to dissolution of P retained in the less labile fraction, demonstrating the influence of organic matter addition on soil P processes that control P availability in soil. As expected, the application of organic wastes increased the degree of P saturation in the soils, however the values obtained did not exceed the limits considered to pose a risk of water pollution. The influence of the application of organic wastes on inorganic and organic soil P forms was also studied in an acid loamy sand soil after long-term field application of cattle manure and biowaste compost and the combined application of compost and mineral fertilizer (triple superphosphate) in a crop rotation. Soil samples were collected 14 years after the establishment of the field experiment, and analyzed for soluble and available P, P sorption capacity, degree of P saturation and enzymatic activities (dehydrogenase, acid phosphatase and alkaline phosphatase). The different forms of organic P in soil were determined by using an enzyme addition technique, based on adding enzymes with different substrate specificities to NaOH-EDTA soil extracts, measuring the hydrolyzed P colorimetrically after an incubation period. The enzymes used were acid phosphatase, nuclease and phytase which allowed to identify hydrolyzable monoesters (monoester-like P) diesters (DNA-like P) and inositol hexakisphosphate (Ins6P-like P). The long-term application of organic wastes increased soil available P proportionally to the P applied with each type of fertilizer, assuming a higher risk of P losses given the high degree of P saturation of this soil. The application of organic wastes increased soil organic P resistant to enzymatic hydrolysis, but no influence was observed regarding the different forms of enzyme hydrolyzable organic P compared to those observed in the non-amended soil. Furthermore, the different forms of organic P applied with the organic wastes did not correspond to those analyzed in the soil which showed that these forms in soil are a result of multifaceted P turnover processes in soil affected by plants, microorganisms and abiotic factors. In this study, a correlation between Ins6P-like P and the microbial activity (dehydrogenase activity) of soil was found, which reinforces this claim. Finally, the application of organic wastes as a source of N and P in agriculture was evaluated agronomically in a real field scenario. A field experiment was established to evaluate the application of compost made from wine-distillery wastes in the same melon crop used in the experiments of N mineralization and leaching. In this experiment the application of three doses of compost were studied: 1 , 2 and 3 kg of compost per linear meter of plantation corresponding to 7, 13 and 20 tonnes of compost per hectare respectively; and the effect on plant growth, N and P accumulation in the plant as well as crop yield and quality was studied. The application of compost produced a slight increase in plant biomass accompanied by a significant improvement in crop yield with respect to the unamended plots, obtaining the maximum yield with the application of 2 kg of compost per linear meter. Although the potential effects of N and P were partially masked by other inputs of these nutrients in the system (high concentration of nitrates in the irrigation water and phosphoric acid supplied by fertigation), an effect of P was observed the first year of study resulting in a greater plant P accumulation and in an increase in the number of fruits in the amended plots. In addition, the higher accumulation of available N and P in the topsoil at the end of the growing season indicated the potential use of this material as source of these nutrients.

Management of Trihalomethanes in Finished Drinking Water Through Source Water Precursor Monitoring

Trihalomethanes are organic compounds formed in drinking water distribution systems as a result of disinfection. This capstone project researched and evaluated the statistical correlation of trihalomethanes in finished drinking water and total organic carbon in source water using data generated by Denver area utilities. Results of the study conclude that some drinking water supply systems show a slight correlation between source water total organic carbon levels and trihalomethane levels in finished water. Results of the study also verify the assertion that changes to treatment for the reduction of trihalomethanes, for the protection of human health under the Safe Drinking Water Act should be determined by each utility, using information from gathered data, seasonal trends, and small scale batch testing.

Grants and loans for municipal water supply and watewater [i.e. wastewater] treatment systems : water conservation provisions : final report of Task Force 11 /

Mode of access: Internet.

Effects of basic tillage methods and soil compaction on corn production /

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Quality control and management of oceanographic wave-gage data /

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Reconstruction of hydraulic management of a water distribution system using optimization /

"October 2001."