Seismic Hazard and Ground Motion Characterization at the Itoiz Dam (Northern Spain).

This paper presents a new hazard-consistent ground motion characterization of the Itoiz dam site, located in Northern Spain. Firstly, we propose a methodology with different approximation levels to the expected ground motion at the dam site. Secondly, we apply this methodology taking into account the particular characteristics of the site and of the dam. Hazard calculations were performed following the Probabilistic Seismic Hazard Assessment method using a logic tree, which accounts for different seismic source zonings and different ground-motion attenuation relationships. The study was done in terms of peak ground acceleration and several spectral accelerations of periods coinciding with the fundamental vibration periods of the dam. In order to estimate these ground motions we consider two different dam conditions: when the dam is empty (T = 0.1 s) and when it is filled with water to its maximum capacity (T = 0.22 s). Additionally, seismic hazard analysis is done for two return periods: 975 years, related to the project earthquake, and 4,975 years, identified with an extreme event. Soil conditions were also taken into account at the site of the dam. Through the proposed methodology we deal with different forms of characterizing ground motion at the study site. In a first step, we obtain the uniform hazard response spectra for the two return periods. In a second step, a disaggregation analysis is done in order to obtain the controlling earthquakes that can affect the dam. Subsequently, we characterize the ground motion at the dam site in terms of specific response spectra for target motions defined by the expected values SA (T) of T = 0.1 and 0.22 s for the return periods of 975 and 4,975 years, respectively. Finally, synthetic acceleration time histories for earthquake events matching the controlling parameters are generated using the discrete wave-number method and subsequently analyzed. Because of the short relative distances between the controlling earthquakes and the dam site we considered finite sources in these computations. We conclude that directivity effects should be taken into account as an important variable in this kind of studies for ground motion characteristics.

Physical characterization of laser interaction and shock generation in laser shock processing: coupled theoretical-experimental analysis

Laser Shock Processing is developing as a key technology for the improvement of surface mechanical and corrosion resistance properties of metals due to its ability to introduce intense compressive residual stresses fields into high elastic limit materials by means of an intense laser driven shock wave generated by laser with intensities exceeding the 109 W/cm2 threshold, pulse energies in the range of 1 Joule and interaction times in the range of several ns. However, because of the relatively difficult-to-describe physics of shock wave formation in plasma following laser-matter interaction in solid state, only limited knowledge is available in the way of full comprehension and predictive assessment of the characteristic physical processes and material transformations with a specific consideration of real material properties. In the present paper, an account of the physical issues dominating the development of LSP processes from a moderately high intensity laser-matter interaction point of view is presented along with the theoretical and computational methods developed by the authors for their predictive assessment and new experimental contrast results obtained at laboratory scale.

Physical characterization of growing media using standard methods (CEN)- Limitations of Applicability for pine bark and vermiculite

CEN standards have helped to harmonize analytical methods for substrate analysis.Though, for special substrates or constituents the applicability might be Iimited. In this paper a comparative study of implementation of CEN standards to samples of pine bark and vermiculite has been carried out. For composted pine bark, an elongation of the equilibrium period up to 72 instead of 48 hours might increase the accuracy of determinations physical parameters according to EN 13041. For vermiculite, we suggest pycnometry as a feasible technique for the determination of particle density (PD), as the determination of organic matter (OM) as requested by EN 13041 for the calculation of the PD seems not to be applicable for this kind of material.

Uncertainties in the design of support structures and foundations for offshore wind turbines

Offshore wind industry has exponentially grown in the last years. Despite this growth, there are still many uncertainties in this field. This paper analyzes some current uncertainties in the offshore wind market, with the aim of going one step further in the development of this sector. To do this, some already identified uncertainties compromising offshore wind farm structural design have been identified and described in the paper. Examples of these identified uncertainties are the design of the transition piece and the difficulties for the soil properties characterization. Furthermore, this paper deals with other uncertainties not identified yet due to the limited experience in the sector. To do that, current and most used offshore wind standards and recommendations related to the design of foundation and support structures (IEC 61400-1, 2005; IEC 61400-3, 2009; DNV-OS-J101, Design of Offshore Wind Turbine, 2013 and Rules and Guidelines Germanischer Lloyd, WindEnergie, 2005) have been analyzed. These new identified uncertainties are related to the lifetime and return period, loads combination, scour phenomenon and its protection, Morison e Froude Krilov and diffraction regimes, wave theory, different scale and liquefaction. In fact, there are a lot of improvements to make in this field. Some of them are mentioned in this paper, but the future experience in the matter will make it possible to detect more issues to be solved and improved.

MEG networks organization is related to white matter integrity

Many studies have assessed the characterization of anatomical or functional connectivity in mild cognitive impairment (MCI), however it is still unknown how they are related in the course of the pathology. Here we integrate the analysis of magnetoencephalographic (MEG) data with white matter (WM) integrity quantification from diffusion weighted imaging (DWI), to asses whether the damage in the WM tracts disrupt the organization of the functional networks.

Caracterizaci��n de los par��metros de resistencia al corte y erosionabilidad del suelo para su aplicaci��n en los problemas de estabilidad de taludes en obras lineales

La tesis se organiza en un volumen de Memoria integrada por once cap��tulos que constituyen el cuerpo de la tesis y otro volumen de Ap��ndices titulado ���Caracterizaci��n geot��cnica de Base de los suelos de Espa��a��� que re��ne en forma de cuadros las caracter��sticas de textura, permeabilidad, humedad-succi��n, erosionabilidad y resistencia al corte de los cuarenta y dos perfiles de suelos representativos de los tipos del Mapa de suelos De Espa��a. Estos cuadros han sido elaborados originalmente por la doctorando durante sus estudios para la obtenci��n del DEA de la Suficiencia Investigadora, excepto los de resistencia al corte que lo han sido tambi��n por la doctorando de forma original, pero ya en la etapa de redacci��n de la tesis. En el Cap��tulo 1 ���Introducci��n��� se describe la motivaci��n, antecedentes, alcance y contenido de la tesis, ordenado seg��n el ��ndice que en ��l se incluye. Los Cap��tulos 2 ���Meteorizaci��n, 3 ���Balance H��drico��� y 4 ���Humedades caracter��sticas��� constituyen el ���estado del arte��� en el momento actual de los temas de geotecnia ambiental relacionados con la degradaci��n de la superficie terrestre y la estabilidad de taludes. El Cap��tulo 2, tras matizar algunas generalidades, aporta elementos para la cuantificaci��n de la alteraci��n de rocas como el �����ndice clim��tico de Weinert��� y de la erosi��n de suelos como la ���ecuaci��n universal de p��rdida de suelo (U.S.L.E.)��� El Cap��tulo 3, partiendo de los fen��menos de precipitaci��n y evapotranspiraci��n, plantea el balance h��drico en vertientes con instrumentos para evaluar la infiltraci��n y la escorrent��a, conceptos imprescindibles para adentrarse en los de resistencia y erosionabilidad del conjunto suelo-agua. En los Ap��ndices A1 y A2, se recogen valores de coeficientes de infiltraci��n en condiciones saturadas y no saturadas de los perfiles de suelos del Mapa de Espa��a. El Cap��tulo 4 se dedica al estudio de este conjunto suelo-agua con la definici��n de conceptos que lo caracterizan, basados en la relaci��n entre los contenidos de ambos elementos o ���humedad���, sus valores m��ximos y m��nimos y la forma en la que es retenida el agua por el suelo. Este cap��tulo acaba con el concepto de ���Curva caracter��stica Suelo-Agua/Soil Water Characteristic curve (SWCC)���, que liga el contenido de agua de un suelo con la tensi��n a la que est�� retenida (uauw) ���succi��n��� o con su expresi��n m��s usual ���pF���. En el Ap��ndice A 3 se adjuntan las SWCC de los perfiles de suelos del Mapa de suelos de Espa��a. En el Cap��tulo 5 ���Resistencia al corte de los suelos���, se detalla la influencia que tienen sobre la resistencia de los suelos factores como el paso del tiempo, el contenido de humedad y la presencia y tipo de vegetaci��n en la superficie del suelo estudiado. El Cap��tulo 6 ���Evaluaci��n de la erosi��n���, analiza el factor de erosionabilidad del suelo ���factor K��� de la U.S.L.E., su evaluaci��n en funci��n de la textura, estructura y permeabilidad del suelo, con la estimaci��n hecha para los cuarenta y dos perfiles de suelos del Mapa de Espa��a, contenida en el Ap��ndice 4. En el Cap��tulo 7 ���Metodolog��a de dise��o��� se hacen en su primera parte unas consideraciones geoambientales de dise��o aplicables al estudio de los problemas de inestabilidades en taludes. La segunda parte constituye el n��cleo de la tesis con la propuesta de ���estimaci��n de los par��metros de resistencia al corte del suelo���, consecuente con las teor��as y metodolog��a de an��lisis expuesta en los cap��tulos anteriores. En el Ap��ndice A 5 se presentan los valores de los par��metros coulombianos de resistencia al corte, ���c y ����� estimados seg��n la caracterizaci��n clim��tica a partir del ��ndice de Thornthwaite, en condicionesde dise��o para humedades naturales m��xima y m��nima de los cuarenta y dos perfiles de suelos del Mapa de suelos de Espa��a. El Cap��tulo 8 ���Aplicaci��n a casos reales��� se considera de gran inter��s al constituir una aut��ntica continuaci��n de la segunda parte del cap��tulo anterior, desarrollando la metodolog��a expuesta en ��l a cuatro problem��ticas de infraestructuras de obras lineales, relacionadas con problemas de erosi��n y deslizamientos en taludes. El Cap��tulo 9 ���Ensayos de referencia��� se incluye como punto de apoyo (referencia) a las teor��as expuestas, valorando la idoneidad de los tipos de ensayos y tipos de suelos seleccionados (Laboratorio de Geotecnia del CEDEX y Laboratorio Hong-Kong University of Science and Technology), utilizados para la obtenci��n, por correlaciones deducidas, de las curvas SWCC de los perfiles de suelos del Mapa de Espa��a, inclu��das en el Ap��ndice A 3, como se ha citado antes. En el Cap��tulo 10 ���Conclusiones y Futuras L��neas de Investigaci��n���se apuntan en primer lugar unas conclusiones que, a juicio de la doctorando, se pueden extraer con inter��s de esta tesis y a continuaci��n se esbozan unas posibles l��neas de investigaci��n, fundamentalmente de tipo experimental, que complementar��an los avances derivados de esta tesis o podr��an esclarecer y abrir nuevas interpretaciones de los fen��menos naturales de erosi��n y estabilidad de taludes en los que ��sta se ha centrado. Finalmente, en el Cap��tulo 11 ���Bibliograf��a��� se han reunido 328 referencias que reflejan una visi��n amplia y bastante completa del tema tratado, obtenida complementando las de tesis anteriores sobre esta singular materia (���Efecto estabilizador de la vegetaci��n en taludes���, L Fort 1975 y ���Determinaci��n de las caracter��sticas de fricci��n en el contacto suelo-geotextil a diferentes succiones, mediante equipos de laboratorio singulares���, E Asanza 2009), con propias de la doctorando (9) y las consideradas de mayor inter��s de los ��ltimos Congresos sobre Suelos no saturados,���Unsat 95���, ���Unsat 2002��� y ���Unsat 2011��� entre otros. ABSTRACT The thesis is organized in a volume of Memory composed of eleven chapters that make up the body of the thesis and other Appendices volume entitled "Geotechnical characterization of basis of the soils of Spain" that combines the characteristics of texture, permeability, moisture-suction, erosionability, and shear strength of forty-two profiles of soils representative of the types of the soil of Spain map in the form of pictures. These pictures have been produced originally by the student during their studies to obtain the DEA of the research, except those of the shear strength, also been done by the PhD student in an original way, but already at the stage of drafting of the thesis. Chapter 1 "Introducci��n" describes the motivation, background, scope and content of the thesis, ordered according to the index that is included. The Chapters: 2 "Weathering, 3 ���Water Balance��� and 4 ���moisture characteristics" are the "State of the art" at the present time of geotechnical environmental issues related to the degradation of the Earth's surface and the slope stability. Chapter 2 after clarify some general information, provides elements for the quantification of the alteration of rocks as "Weinert climate index" and soil erosion as the "universal equation of loss of soil (U.S.L.E.)" Chapter 3, on the basis of the phenomena of precipitation and evapotranspiration, raises the water balance in sheds with instruments to evaluate infiltration and runoff, essential concepts into the resistance and erosionability water-soil joint. Values of soils coefficients of infiltration in saturated and unsaturated conditions from the Spain map of profiles are collected in the Appendices A1 and A2. Chapter 4 is dedicated to the study of this joint ���soil-water���, with the definition of concepts that characterize it, based on the relationship between the contents of both elements or ���moisture���, their maximum and minimum values and the way in which water is retained by the soil. This chapter ends with the concept of ���Soil Water Characteristic curve (SWCC)", which linked the water content of a soil with the stress that it is retained (ua-uw) "suction" or its expression more usual "pF". The SWCC of the profiles of soils of the Spain soils Map are attached in the Appendix 3. In Chapter 5 ���Soils shear strength���,is detailed the influence that they have on the resistance of soils factors such as the passage of time, the content of moisture and the presence and type of vegetation on the surface of the studied soil. Chapter 6 "Assessment of erosion", analyses the soil erodibility factor "Kfactor" of the U.S.L.E., its evaluation based on texture, structure and permeability of the soil, with the estimate for forty-two profiles of soils on the Spain Soils Map, contained in Appendix 4. Chapter 7 "Design methodology" some considerations are made in the first part geo-environmental design applicable to the study of the problems of instabilities in slopes. The second part constitutes the core of the thesis with the proposal of ���estimation of parameters of shear strength���, of the soils consistent with theories and analytical methodology outlined in the previous chapters. Appendix A 5 presents the values of the coulombians parameters of shear strength, "c and ��" according to the characterization of climate from the index of Thornthwaite, in design for natural moisture conditions maximum and minimum of forty-two profils of Spain Soils Map Chapter 8 "Application to real cases" is considered of great interest to constitute a true continuation of the second part of the previous chapter, developing the methodology exposed it to four problems of civil-works infrastructure, related to problems of erosion and landslides in slopes. Chapter 9 "Tests of reference" is included as point of support (reference) to the theories exposed, assessing the suitability of the types of tests and types of selected soils (Geotechnical laboratory of CEDEX and laboratory Hongkong University of Science and Technology), used to obtain, by deduced correlations, of curves SWCC of soils profiles on the Spain Soils Map, included in Appendix A. 3, as it was mentioned before. Chapter 10 "Conclusions and future research lines" are running first conclusions which, in the opinion of the candidate, can be extracted with interest of this thesis, and then, it outlines some possible lines of research, mainly experimental, which would complement the advances arising from this thesis or could clarify and open new interpretations of natural phenomena of erosion and slope stability in which it has focused. Finally, in Chapter 11 "Bibliography" 328 references have been included which reflect a broad and fairly comprehensive view of the subject matter, obtained complementing those of the previous theses on this singular issue ("Vegetation stabilizing effect on slopes", L Fort 1975, and "Determination of the characteristics of friction in the contact soil-geotextile to different-suctions, through special laboratory equipment", E Asanza 2009) with some of them from of the candidate (9) and the others from of the considered as the most interesting of recent conferences on unsaturated soils, "Unsat 95", "Unsat2002" and "Unsat 2011" among others.

Multimodal integration of functional and structural brain connectivity. An application to the characterization of Mild Cognitive Impairment

La investigaci��n para el conocimiento del cerebro es una ciencia joven, su inicio se remonta a Santiago Ram��n y Cajal en 1888. Desde esta fecha a nuestro tiempo la neurociencia ha avanzado mucho en el desarrollo de t��cnicas que permiten su estudio. Desde la neurociencia cognitiva hoy se explican muchos modelos que nos permiten acercar a nuestro entendimiento a capacidades cognitivas complejas. Aun as�� hablamos de una ciencia casi en pa��ales que tiene un lago recorrido por delante. Una de las claves del ��xito en los estudios de la funci��n cerebral ha sido convertirse en una disciplina que combina conocimientos de diversas ��reas: de la f��sica, de las matem��ticas, de la estad��stica y de la psicolog��a. Esta es la raz��n por la que a lo largo de este trabajo se entremezclan conceptos de diferentes campos con el objetivo de avanzar en el conocimiento de un tema tan complejo como el que nos ocupa: el entendimiento de la mente humana. Concretamente, esta tesis ha estado dirigida a la integraci��n multimodal de la magnetoencefalograf��a (MEG) y la resonancia magn��tica ponderada en difusi��n (dMRI). Estas t��cnicas son sensibles, respectivamente, a los campos magn��ticos emitidos por las corrientes neuronales, y a la microestructura de la materia blanca cerebral. A lo largo de este trabajo hemos visto que la combinaci��n de estas t��cnicas permiten descubrir sinergias estructurofuncionales en el procesamiento de la informaci��n en el cerebro sano y en el curso de patolog��as neurol��gicas. M��s espec��ficamente en este trabajo se ha estudiado la relaci��n entre la conectividad funcional y estructural y en c��mo fusionarlas. Para ello, se ha cuantificado la conectividad funcional mediante el estudio de la sincronizaci��n de fase o la correlaci��n de amplitudes entre series temporales, de esta forma se ha conseguido un ��ndice que mide la similitud entre grupos neuronales o regiones cerebrales. Adicionalmente, la cuantificaci��n de la conectividad estructural a partir de im��genes de resonancia magn��tica ponderadas en difusi��n, ha permitido hallar ��ndices de la integridad de materia blanca o de la fuerza de las conexiones estructurales entre regiones. Estas medidas fueron combinadas en los cap��tulos 3, 4 y 5 de este trabajo siguiendo tres aproximaciones que iban desde el nivel m��s bajo al m��s alto de integraci��n. Finalmente se utiliz�� la informaci��n fusionada de MEG y dMRI para la caracterizaci��n de grupos de sujetos con deterioro cognitivo leve, la detecci��n de esta patolog��a resulta relevante en la identificaci��n precoz de la enfermedad de Alzheimer. Esta tesis est�� dividida en seis cap��tulos. En el cap��tulos 1 se establece un contexto para la introducci��n de la connect��mica dentro de los campos de la neuroimagen y la neurociencia. Posteriormente en este cap��tulo se describen los objetivos de la tesis, y los objetivos espec��ficos de cada una de las publicaciones cient��ficas que resultaron de este trabajo. En el cap��tulo 2 se describen los m��todos para cada t��cnica que fue empleada: conectividad estructural, conectividad funcional en resting state, redes cerebrales complejas y teor��a de grafos y finalmente se describe la condici��n de deterioro cognitivo leve y el estado actual en la b��squeda de nuevos biomarcadores diagn��sticos. En los cap��tulos 3, 4 y 5 se han incluido los art��culos cient��ficos que fueron producidos a lo largo de esta tesis. Estos han sido incluidos en el formato de la revista en que fueron publicados, estando divididos en introducci��n, materiales y m��todos, resultados y discusi��n. Todos los m��todos que fueron empleados en los art��culos est��n descritos en el cap��tulo 2 de la tesis. Finalmente, en el cap��tulo 6 se concluyen los resultados generales de la tesis y se discuten de forma espec��fica los resultados de cada art��culo. ABSTRACT In this thesis I apply concepts from mathematics, physics and statistics to the neurosciences. This field benefits from the collaborative work of multidisciplinary teams where physicians, psychologists, engineers and other specialists fight for a common well: the understanding of the brain. Research on this field is still in its early years, being its birth attributed to the neuronal theory of Santiago Ramo��n y Cajal in 1888. In more than one hundred years only a very little percentage of the brain functioning has been discovered, and still much more needs to be explored. Isolated techniques aim at unraveling the system that supports our cognition, nevertheless in order to provide solid evidence in such a field multimodal techniques have arisen, with them we will be able to improve current knowledge about human cognition. Here we focus on the multimodal integration of magnetoencephalography (MEG) and diffusion weighted magnetic resonance imaging. These techniques are sensitive to the magnetic fields emitted by the neuronal currents and to the white matter microstructure, respectively. The combination of such techniques could bring up evidences about structural-functional synergies in the brain information processing and which part of this synergy fails in specific neurological pathologies. In particular, we are interested in the relationship between functional and structural connectivity, and how two integrate this information. We quantify the functional connectivity by studying the phase synchronization or the amplitude correlation between time series obtained by MEG, and so we get an index indicating similarity between neuronal entities, i.e. brain regions. In addition we quantify structural connectivity by performing diffusion tensor estimation from the diffusion weighted images, thus obtaining an indicator of the integrity of the white matter or, if preferred, the strength of the structural connections between regions. These quantifications are then combined following three different approaches, from the lowest to the highest level of integration, in chapters 3, 4 and 5. We finally apply the fused information to the characterization or prediction of mild cognitive impairment, a clinical entity which is considered as an early step in the continuum pathological process of dementia. The dissertation is divided in six chapters. In chapter 1 I introduce connectomics within the fields of neuroimaging and neuroscience. Later in this chapter we describe the objectives of this thesis, and the specific objectives of each of the scientific publications that were produced as result of this work. In chapter 2 I describe the methods for each of the techniques that were employed, namely structural connectivity, resting state functional connectivity, complex brain networks and graph theory, and finally, I describe the clinical condition of mild cognitive impairment and the current state of the art in the search for early biomarkers. In chapters 3, 4 and 5 I have included the scientific publications that were generated along this work. They have been included in in their original format and they contain introduction, materials and methods, results and discussion. All methods that were employed in these papers have been described in chapter 2. Finally, in chapter 6 I summarize all the results from this thesis, both locally for each of the scientific publications and globally for the whole work.

Effects of soil management in vineyard on soil physical and chemical characteristics

Cover crops in Mediterranean vineyards are scarcely used due to water competition between the cover crop and the grapevine; however, bare soil management through tillage or herbicides tends to have negative effects on the soil over time (organic matter decrease, soil structure and soil fertility degradation, compaction, etc). The objective of this study was to understand how soil management affects soil fertility, compaction and infiltration over time. To this end, two bare soil techniques were compared, tillage (TT) and total herbicide (HT) with two cover crops; annual cereal (CT) and annual grass (AGT), established for 8 years. CT treatment showed the highest organic matter content, having the biggest amount of biomass incorporated into the soil. The annual adventitious vegetation in TT treatment (568 kg dry matter ha-1) that was incorporated into the soil, kept the organic matter content higher than HT levels and close to AGT level, in spite of the greater aboveground annual biomass production of this treatment (3632 kg dry matter ha-1) whereas only its roots were incorporated into the soil. TT presented the highest bulk density under the tractor track lines and a greatest resistance to penetration (at 0.2 m depth). AGT presented bulk density values (upper 0.4 m) lower than TT and penetration resistance in CT lower (at 0.20 m depth) than TT too. Effects of soil management in vineyard on soil physical and chemical characteristics - ResearchGate. Available from: http://www.researchgate.net/publication/268520480_Effects_of_soil_management_in_vineyard_on_soil_physical_and_chemical_characteristics [accessed May 20, 2015].

Factors driving the carbon mineralization priming effect in a sandy loam soil amended with different types of biochar

The effect of biochar on the soil carbon mineral- ization priming effect depends on the characteristics of the raw materials, production method and pyrolysis conditions. The goal of the present study is to evaluate the impact of three different types of biochar on physicochemical properties and CO2 emissions of a sandy loam soil. For this purpose, soil was amended with three different biochars (BI, BII and BIII) at a rate of 8 wt % and soil CO2 emissions were measured for 45 days. BI is produced from a mixed wood sieving from wood chip production, BII from a mixture of paper sludge and wheat husks and BIII from sewage sludge. Cumulative CO2 emissions of biochars, soil and amended soil were well fit to a simple first-order kinetic model with correlation coef- ficients (r 2 ) greater than 0.97. Results show a negative prim- ing effect in the soil after addition of BI and a positive prim- ing effect in the case of soil amended with BII and BIII. These results can be related to different biochar properties such as carbon content, carbon aromaticity, volatile matter, fixed carbon, easily oxidized organic carbon or metal and phenolic substance content in addition to surface biochar properties. Three biochars increased the values of soil field capacity and wilting point, while effects over pH and cation exchange capacity were not observed.

Identificaci��n de ��reas prioritarias para la conservaci��n de razas de ma��z en la sierra de Ecuador

En Ecuador el ma��z es el cultivo m��s importante en superficie y es base de la alimentaci��n para la poblaci��n rural que vive en los Andes. A diferencia de lo que sucede en la Costa, en la regi��n Sierra todav��a se cultivan numerosas variedades tradicionales que se agrupan en veinticuatro razas. Mantener esta diversidad es, pues, de gran importancia no solo para la seguridad alimentaria, sino tambi��n como fuente de genes para tolerancia a factores abi��ticos que podr��an ser incorporados a las variedades modernas. Si bien parte de esta diversidad fue recolectada a mediados del siglo pasado y est�� siendo conservada en distintos bancos de germoplasma, es deseable que su conservaci��n in situ tambi��n est�� asegurada, entre otras razones, porque de esta manera el cultivo puede seguir evolucionando. Para poder implementar un plan de conservaci��n en finca que contribuya a preservar este patrimonio, resulta imprescindible identificar ��reas id��neas donde concentrar los recursos y conocer las caracter��sticas y tipolog��as de los agricultores que manejan la diversidad actual. Generar esta informaci��n es el objetivo principal de esta investigaci��n y para lograrlo se han llevado a cabo cuatro estudios: (1) An��lisis de la diversidad a nivel de razas e identificaci��n de ��reas de alta riqueza de razas, alta diversidad morfol��gica y/o alta diversidad ecogeogr��fica en la Sierra de Ecuador, (2) Identificaci��n del perfil y las caracter��sticas de los agricultores que conservan y manejan las variedades tradicionales de ma��z en la Sierra de Ecuador, (3) An��lisis del conocimiento local, manejo y usos de variedades tradicionales de ma��z en la Sierra de Ecuador, y (4) Identificaci��n de ��reas de alta diversidad y bajo riesgo de p��rdida para la conservaci��n en finca de ma��z en la Sierra de Ecuador. Para el primer estudio se visitaron 303 fincas distribuidas a lo largo de la Sierra y se recolectaron 636 muestras que fueron caracterizadas morfol��gicamente mediante 14 variables: 8 relacionadas con la mazorca (forma, longitud y di��metro de la mazorca, color y di��metro de olote y n��mero y disposici��n de hileras) y 7 referidas el grano (n��mero total de granos, color, forma, longitud, anchura y grosor de grano y tipo de endospermo). Adicionalmente, las fincas donde se tomaron las muestras fueron caracterizadas ecogeogr��ficamente mediante 5 variables clim��ticas (temperatura media estacional, rango de temperatura media anual, temperatura m��nima de diciembre, precipitaci��n estacional y precipitaci��n de octubre), 2 geof��sicas (altitud y pendiente) y 5 ed��ficas (textura principal del suelo, profundidad a roca, pH, contenido en materia org��nica y fertilidad). A partir de esta informaci��n y mediante t��cnicas de sistemas de informaci��n geogr��fica (SIG), se generaron mapas de distribuci��n por raza en formato vectorial y un mapa de riqueza de razas, un mapa de diversidad morfol��gica y un mapa de diversidad ecogeogr��fica en formato r��ster con celdas de 10 km x 10 km. Los resultados permitieron constatar que, en los ��ltimos 60 a��os, no se ha perdido ninguna raza. Sin embargo, Canguil, Chaucho y Clavito han dejado de cultivarse en algunas provincias con la consiguiente erosi��n gen��tica del cultivo. La caracterizaci��n morfol��gica detect�� diferencias en el grado de variabilidad intra-raza, siendo Patillo Ecuatoriano, Racimo de Uva y Uchima las razas m��s heterog��neas tanto para los caracteres cualitativos como cuantitativos. A nivel clim��tico y geof��sico, tambi��n se detectaron diferencias en el grado de variaci��n intra-raza; Cuzco Ecuatoriano, Kcello Ecuatoriano y Monta��a Ecuatoriana fueron las razas que en promedio presentaron mayores rangos y coeficientes de variaci��n para estas variables ecogeogr��ficas. En cuanto a las condiciones ed��ficas todas las razas, excepto C��nico Dentado, presentaron una gran heterogeneidad, pudiendo crecer tanto en suelos ricos como pobres, con valores de pH entre ��cido y moderadamente alcalino. La comparaci��n entre razas revel�� diferencias significativas en los rangos ambientales de algunas razas como C��nico Dentado, que tiende a cultivarse a menor altitud y, por tanto, en ambientes menos fr��os y de mayor precipitaci��n que Blanco Blandito, Patillo Ecuatoriano, Sabanero Ecuatoriano, Uchima y Zhima. Para la mayor��a de las razas se encontraron materiales potencialmente adaptados a condiciones de estr��s (precipitaci��n estacional inferior a 500 mm y suelos con pH entre 4.5 y 5.5). Finalmente, los mapas de riqueza, de diversidad morfol��gica y de diversidad ecogeogr��fica mostraron 36 celdas de alta diversidad repartidas en las 10 provincias de la Sierra: 11 celdas en las provincias del norte, 11 en las provincias del centro y 14 en las provincias del sur. Para la caracterizaci��n e identificaci��n de las tipolog��as de los agricultores que cultivan ma��z en la Sierra de Ecuador y el an��lisis de los posibles factores de riesgo de p��rdida de diversidad, se realizaron entrevistas individuales y semiestructuradas a los agricultores due��os de las fincas donde se recolectaron las muestras para el estudio de diversidad (254 en total). Las preguntas que se formularon (11 abiertas y 5 cerradas) estuvieron organizadas en seis bloques: datos del agricultor, caracter��sticas de la finca, diversidad y conocimiento del cultivo, manejo del cultivo, usos y flujo de semillas. Los resultados indicaron que la diversidad de ma��z que hay en la Sierra de Ecuador es manejada mayoritariamente por agricultores mestizos, de entre 30 y 55 a��os, que cultivan una o dos variedades tradicionales para autoconsumo, en parcelas de menos de 0.5 ha y en asocio con fr��jol. El an��lisis de segmentaci��n mediante el algoritmo Chi-square automatic interaction detection (CHAID) permiti�� identificar un peque��o grupo de agricultores ind��genas con parcelas medianas (entre 0.5 ha y 1.5 ha) que conservan un mayor n��mero de variedades tradicionales por finca que el agricultor promedio. Los an��lisis estad��sticos no detectaron diferencias significativas entre etnias (mestizo vs. ind��gena), g��neros (hombre vs. mujer) y grupos de edad (j��venes menores de 30 a��os, adultos entre 30 y 55 a��os y adultos mayores de 55 a��os) en lo que respecta al conocimiento del cultivo (criterios de reconocimiento y razones de preferencia) y manejo (tipo de cultivo), pero s�� detectaron diferencias entre regiones, principalmente en el modo de cultivar el ma��z; mientras que en el norte y sur tienden a sembrarlo en asocio y con un mayor n��mero de especies, en el centro acostumbran a cultivarlo preferentemente solo. En cuanto a los usos, se recopilaron hasta 39 modos diferentes de consumir ma��z, siendo Kcello Ecuatoriano y Zhima las razas para las que se registr�� un mayor n��mero de usos. La comparaci��n del n��mero medio de usos por variedad entre etnias evidenci�� que los agricultores mestizos utilizan sus variedades tradicionales de forma m��s variada que los ind��genas. Entre los factores de riesgo que se analizaron, el bajo porcentaje de j��venes agricultores que se ocupan de las fincas podr��a suponer una amenaza a medio plazo por falta de relevo generacional. Adicionalmente, las numerosas sinonimias y homonimias que se detectaron y el bajo intercambio de semillas tambi��n podr��an ser causa de p��rdida de diversidad, bien por reemplazo o por envejecimiento de la semilla. Finalmente, se concluy�� que las razas Chaucho, Complejo Chillo-Huandango, Complejo Mishca-Huandango, C��nico Dentado, Monta��a Ecuatoriana y Sabanero Ecuatoriano son particularmente vulnerables, no solo por su baja presencia, sino tambi��n por el color de grano que tienen (los mismos que la mayor��a de las razas m��s comunes) y carecer de nombres y usos espec��ficos. Finalmente, para la priorizaci��n de ��reas de conservaci��n en finca para ma��z en la Sierra de Ecuador, se utilizaron 13 criterios de diferente naturaleza: 2 ecogeogr��ficos (precipitaci��n, diversidad ecogeogr��fica), 6 biol��gicos (grado de presencia del cultivo, riqueza de razas, diversidad morfol��gica, presencia de mezclas, presencia de razas locales y riesgo de erosi��n gen��tica), 3 culturales (abundancia de variedades por finca, diversidad de usos y frecuencia de intercambio) y 2 demogr��ficos (tama��o de la poblaci��n y distancia a n��cleos urbanos). Mediante t��cnicas SIG y de evaluaci��n multicriterio, los valores originales de las capas-criterio fueron transformados a una escala de 0 a 100. Posteriormente, las capas-criterio normalizadas fueron sumadas utilizando tres m��todos de ponderaci��n: (1) mismo peso, (2) diferente peso seg��n la puntuaci��n otorgada por 72 expertos, y (3) diferente peso seg��n el m��todo de comparaci��n entre pares de criterios. Los resultados permitieron identificar ocho celdas de 10 km x 10 km con alta puntuaci��n (> 65): tres celdas en el norte (una en cada una de las provincias), una celda en el centro (en la provincia de Cotopaxi), y cuatro celdas en la regi��n sur (dos en Azuay y otras dos en Loja). ABSTRACT In Ecuador, the maize is the most important cultivation in surface and it is a base of the feeding for the rural population who lives in the Andes. In contrast to what it happens on the Coast, in the Sierra region still there are cultivated numerous traditional varieties that are grouped into twenty-four races. Maintaining this diversity is, therefore, of great importance not only for food security, but also as a source of genes for tolerance to abiotic factors could be incorporated into modern varieties. Although part of this diversity was collected in the middle of the last century and is still preserved in various germplasm banks, it is desirable for the in situ conservation also is assured, among other reasons, because in this way the crop can continue to evolve. To be able to implement a conservation plan on farm that contribute to preserving this heritage, it is essential to identify suitable areas where to concentrate resources and know the characteristics and typology of farmer who managed the current diversity. To generate this information is the main target of this investigation and to achieve this, four studies have been carried out: (1) Analysis of the diversity at races and identification of areas of high richness of races, high morphological diversity and / or ecogeographical high diversity in the Sierra of Ecuador, (2) Identification of the profile and characteristics of farmers who conserve and manage traditional varieties of maize in the Sierra of Ecuador, (3) Analysis of local knowledge, management and use of traditional varieties of maize in the Sierra of Ecuador, and (4) Identification of areas of high diversity and low risk of loss for the conservation of maize in the Sierra of Ecuador. For the first study were visited 303 farms distributed along the Sierra and collected 636 samples that were characterized morphologically by 14 variables: 8 related to the ear (shape, length and diameter of the cob, colour, and diameter of cob and number and arrangement of rows) and 7 referred to the grain (total number of grain, colour, shape, length, width, and thickness and type of grain endosperm). In addition, the farms where the samples were taken were characterized ecogeographically through 5 climatic variables (seasonal average temperature, range of average annual temperature, minimum temperature for December, seasonal precipitation and precipitation of October), 2 geophysical (altitude and slope) and edaphic 5 (main texture of the soil, deep rock, pH, content of organic matter and fertility). From this information and techniques of geographic information systems (GIS), maps were generated for distribution by race in vector format and a map of richness of races, a map of morphological diversity and a map of ecogeographical diversity in raster format with cells of 10 km x 10 km. The results allowed observing that, over the past 60 years, it has not lost any race. Nevertheless, Canguil, Chaucho and Clavito have stopped being cultivated in some provinces with the consequent genetic erosion of the cultivation. The morphological characterization detected differences in the degree of variability intra-race, being Patillo Ecuatoriano, Racimo de Uva and Uchima races more heterogeneous both for the qualitative and quantitative characters. At climate and geophysical level, also detected differences in the degree of variation intra-race; Cuzco Ecuatoriano, Kcello Ecuatoriano and Monta��a Ecuatoriana were races that, on average, showed higher ranges and coefficients of variation for these geographical characters. In terms of the edaphic conditions, all races, except C��nico Dentado, showed a great heterogeneity, and can grow both in rich and poor soils, with pH values between acid and moderately alkaline. The comparison between races revealed significant differences in the environmental ranges in some races as C��nico Dentado, which tends to be grown at lower elevations and, therefore, in environments less cold and greater precipitation than Blanco Blandito, Patillo Ecuatoriano, Sabanero Ecuatoriano, Uchima and Zhima. For most of the races were found materials potentially adapted to stress conditions (seasonal precipitation less than 500 mm and soil with a pH between 4.5 and 5.5). Finally, the maps of richness, morphologic diversity and ecogeographical diversity showed 36 cells high diversity distributed in 10 provinces of the Sierra: 11 cells in the northern provinces, 11 in the central provinces and 14 in the southern provinces. For the characterization and identification of the typology of the farmers who cultivate corn in the Sierra of Ecuador and the analysis of the possible factors of risk of loss of diversity, there were realized interviews individual and semistructured to the farmers��� owners of the farms where the samples were gathered for the study of diversity (254 in whole). The questions that were formulated (11 opened ones and 5 closed ones) were organized in six blocks: data of the farmer, characteristics of the farm, diversity and knowledge of the crop, crop management, uses and seed flow. The results indicated that the maize diversity that exist in the Sierra of Ecuador is managed mainly by mestizo farmers, aged between 30 and 55, who cultivate one or two traditional varieties for self-consumption, on plots of less than 0.5 has and in associated with beans. The segmentation analysis algorithm using the Chi-square automatic interaction detection (CHAID technique), allowed to identify a small group of indigenous farmers with medium-sized plots (between 0.5 there is and 1.5 it is) that a major number of traditional varieties preserves for farm that the average farmer. The statistical analysis did not detect significant differences between ethnic groups (mestizos vs. indigenous), genres (man vs. women) and age groups (young people under 30 years of age, adults between 30 and 55 years and adults over 55 years old) in regards to the knowledge of the cultivation (recognition criteria and reasons of preference) and management (type of crop), but if detected differences between regions, mainly on the mode of cultivating the maize; while in the north and south they tend to sow in associate and with a greater number of species, in the center accustomed to cultivate it preferably only. In regards to the uses, they were compiled up to 39 different ways of consuming maize, being Kcello Ecuatoriano and Zhima the races for which a major number of uses registered. The comparison of the average number of uses per variety between ethnic groups showed that the mestizo farmers used their traditional varieties of form more varied than the indigenous people. Between the factors of risk that were analyzed, the low percentage of young farmers who deal with the farms might suppose a medium-term threat for lack of generational relief. In addition, the numerous synonyms and homonyms that were detected and the low seed exchange could also be a cause of loss of diversity, either by replacement or by aging of the seed. Finally, it was concluded that the races Chaucho, Complex Chillo-Huandango, Complex Mishca-Huandango, C��nico Dentado, Monta��a Ecuatoriana and Sabanero Ecuatoriano are particularly vulnerable, not only because of their low presence, but also by the grain color they have (the same as the majority of races more common) and lack of names and specific uses. Finally, for the prioritization of maize conservation areas on farm in the Sierra of Ecuador, used 13 criteria of different nature: 2 ecogeographic (precipitation, diversity ecogeographical), 6 biological (degree of presence of the crop, races richness, morphological diversity, the presence of mixtures, presence of local races and risk of genetic erosion), 3 cultural (abundance of varieties per farm, diversity of uses and frequency of exchange) and 2 demographic (population size and distance to urban centers). Using GIS techniques and multicriteria evaluation, the original values of the layers-criterion were transformed to a scale of 0 to 100. Later, the normalized layers - criteria were added using three weighting methods: (1) the same weight, (2) different weight according to the score given by 72 experts, and (3) different weight according to the method of comparison between pairs of criteria. The results allowed to identify eight 10 km cells x 10 km with high punctuation (> 65): three cells in the north (one in each of the provinces), a cell in the center (in the Cotopaxi province), and four cells in the south region (two in Azuay and other two in Loja).

Yield, nutrient utilization and soil properties in a melon crop amended with wine-distillery waste

In Spain, large quantities of wine are produced every year (3,339,700 tonnes in 2011) (FAO, 2011) with the consequent waste generation. During the winemaking process, solid residues like grape stalks are generated, as well as grape marc and wine lees as by-products. According to the Council Regulation (EC) 1493/1999 on the common organization of the wine market, by-products coming from the winery industry must be sent to alcohol-distilleries to generate exhausted grape marc and vinasses. With an adequate composting treatment, these wastes can be applied to soils as a source of nutrients and organic matter. A three-year field experiment (2011, 2012 and 2013) was carried out in Ciudad Real (central Spain) to study the effects of wine-distillery waste compost application in a melon crop (Cucumis melo L.). Melon crop has been traditionally cultivated in this area with high inputs of water and fertilizers, but no antecedents of application of winery wastes are known. In a randomized complete block design, four treatments were compared: three compost doses consisted of 6.7 (D1), 13.3 (D2) and 20 t compost ha-1 (D3), and a control treatment without compost addition (D0). The soil was a shallow sandy-loam (Petrocalcic Palexeralfs) with a depth of 0.60 m and a discontinuous petrocalcic horizon between 0.60 and 0.70 m, slightly basic (pH 8.4), poor in organic matter (0.24%), rich in potassium (410 ppm) and with a medium level of phosphorus (22.1 ppm). During each growing period four harvests were carried out and total and marketable yield (fruits weighting <1 kg or visually rotten were not considered), fruit average weight and fruit number per plant were determined. At the end of the crop cycle, four plants per treatment were sampled and the nutrient content (N, P and K) was determined. Soil samplings (0-30 cm depth) were carried before the application of compost and at the end of each growing season and available N and P, as well as exchangeable K content were analyzed. With this information, an integrated analysis was carried out with the aim to evaluate the suitability of this compost as organic amendment.

Nematodes as indicators of the effect of soil fumigants on soil functioning

Debido al futuro incierto de la mayor parte de los fumigantes ed��ficos usados actualmente en la Uni��n Europea, que pueden implicar riesgos para la salud humana/animal y el medio ambiente, es necesario desarrollar programas de manejo integrado para el control de plagas de cultivos. Estos programas se incluyen como obligatorios en el Reglamento (EC) No. 1107/2009. De acuerdo con este Reglamento, es obligatoria la evaluaci��n del riesgo asociado al uso de productos fitosanitarios sobre los organismos ed��ficos no diana y sus funciones, adem��s de llevar a cabo ensayos con diferentes especies indicadoras para obtener datos de toxicidad que puedan ser usados posteriormente en la evaluaci��n de riesgo. Sin embargo, la baja representatividad de algunas de estas especies indicadoras en el ��rea Mediterr��nea supone una gran limitaci��n. En esta situaci��n, el Panel Cient��fico de Productos Fitosanitarios y sus Residuos de la Autoridad Europea en Seguridad Alimentaria (EFSA), ha se��alado la necesidad de modificar los datos ecotoxicol��gicos requeridos para evaluar los efectos adversos de los productos fitosanitarios de una manera m��s integrada, incluyendo criterios funcionales y estructurales mediante organismos como bacterias, hongos, protozoos y nematodos. De este modo, la EFSA ha recomendado el uso de los nematodos en la evaluaci��n de la funcionalidad y estructura del suelo. Los nematodos est��n globalmente distribuidos y son morfol��gicamente diversos; esto junto con su gran abundancia y diversidad de respuestas a las perturbaciones ed��ficas, los convierte en indicadores adecuados del estado del suelo. Puesto que los nematodos interaccionan con muchos otros organismos que participan en diferentes eslabones de la red tr��fica ed��fica, jugando papeles importantes en procesos ed��ficos esenciales en los agroescosistemas, la diversidad de nematodos es, a menudo, usada como indicador biol��gico de los efectos de las pr��cticas agr��colas en el estado del suelo. En los ��ltimos a��os, diferentes ��ndices basados en la comunidad nematol��gica han facilitado la interpretaci��n de datos complejos sobre la ecolog��a del suelo. Los ��ndices de la red tr��fica ed��fica, basados en la abundancia de grupos funcionales definidos como grupos C-P y grupos tr��ficos, permiten la evaluaci��n de la funcionalidad de la red tr��fica ed��fica. Por otra parte, la dificultad en la identificaci��n taxon��mica de nematodos para explicar su uso limitado como indicadores ecol��gicos, es ampliamente discutida, y existe cierta controversia en cuanto a la eficacia de los diferentes m��todos de identificaci��n de nematodos. Se argumenta que la identificaci��n morfol��gica es dif��cil y puede llevar mucho tiempo debido a la falta de expertos especializados, y se afirma que las t��cnicas moleculares pueden resolver algunas limitaciones de las t��cnicas morfol��gicas como la identificaci��n de juveniles. Sin embargo, los m��todos de identificaci��n molecular tienen tambi��n limitaciones; la mayor��a de las bases de datos de secuencias de ADN est��n fuertemente orientadas hacia los nematodos fitopar��sitos, los cuales representan s��lo una parte de la comunidad ed��fica de nematodos, mientras que hay poca informaci��n disponible de nematodos de vida libre a pesar de representar la mayor��a de los nematodos ed��ficos. Este trabajo se centra en el estudio de los efectos de fumigantes ed��ficos en la funcionalidad del suelo a trav��s del uso de diferentes indicadores basados en la comunidad de nematodos, como los ��ndices de la red tr��fica, ��ndices de diversidad, abundancia de los taxones m��s relevantes etc. Tambi��n se han analizado otros indicadores funcionales relacionados con la supresividad ed��fica, el ciclo de nutrientes o la actividad de la microfauna del suelo. En el cap��tulo 1, la diversidad de nematodos estudiada en una explotaci��n comercial de fresa y sus alrededores durante dos campa��as consecutivas en el suroeste espa��ol, fue baja en los suelos fumigados con fumigantes qu��micos ambas campa��as y, aunque se observ�� una recuperaci��n a lo largo de la campa��a en la zona tratada, los suelos fumigados mostraron una condici��n perturbada permanente. La comunidad de nematodos estuvo m��s asociada al ciclo de nutrientes en la zona sin cultivar que en los suelos cultivados, y se observ�� poca relaci��n entre la biomasa de las plantas y la estructura de la comunidad de nematodos. Los surcos sin tratar dentro de la zona de cultivo funcionaron como reservorio tanto de nematodos fitopar��sitos como beneficiosos; sin embargo estas diferencias entre los surcos y los lomos de cultivo no fueron suficientes para mantener la supresividad ed��fica en los surcos. Los suelos tratados fueron menos supresivos que los suelos sin tratar, y se observaron correlaciones positivas entre la supresividad ed��fica y la estructura de la red tr��fica ed��fica y la diversidad de nematodos. En el cap��tulo 2, se evaluaron los efectos de dos pesticidas org��nicos con efecto nematicida y dos nematicidas convencionales sobre las propiedades f��sico qu��micas del suelo, la diversidad de nematodos y la biomasa de las plantas en condiciones experimentales en dos tipos de suelo: suelos agr��colas poco diversos y suelos provenientes de una zona de vegetaci��n natural muy diversos. El mayor efecto se observ�� en el tratamiento con neem, el cual indujo un gran incremento en el n��mero de dauerlarvas en los suelos pobres en nutrientes, mientras que el mismo tratamiento indujo un incremento de poblaciones de nematodos bacter��voros, m��s estables y menos oportunistas, en los suelos del pinar ricos en materia org��nica. En el cap��tulo 3, se compar�� la eficacia de m��todos moleculares (TRFLP, Terminal Restriction Fragment Length Polymorphism) y morfol��gicos (microscop��a de alta resoluci��n) para la identificaci��n de diferentes comunidades denematodos de Espa��a e Irlanda. Se compararon estad��sticamente las diferencias y similitudes en la diversidad de nematodos, otros indicadores ecol��gicos y de la red tr��fica ed��fica. Las identificaciones mediante el uso de TRFLP s��lo detect�� un porcentaje de los taxones presentes en las muestras de suelo identificadas morfol��gicamente, y los nematodos omn��voros y predadores no fueron detectados molecularmente en nuestro estudio. Los ��ndices calculados en base a los nematodos micr��boros mostraron m��s similitud cuando se identificaron morfol��gica y molecularmente que los ��ndices basados en grupos tr��ficos m��s altos. Nuestros resultados muestran que, al menos con la t��cnica usada en este estudio, la identificaci��n morfol��gica de nematodos es una herramienta fiable y m��s precisa que la identificaci��n molecular, puesto que en general se obtiene una mayor resoluci��n en la identificaci��n de nematodos. En el cap��tulo 4, se estudiaron tambi��n los efectos de los nematicidas qu��micos sobre la comunidad de nematodos y la biomasa de las plantas en condiciones experimentales de campo, donde se aplicaron en una rotaci��n de cultivo jud��a-col durante un ciclo de cultivo. Se aplicaron dos tipos de enmiendas org��nicas con el objetivo de mitigar el efecto negativo de los productos fitosanitarios sobre la diversidad ed��fica. El efecto de los nematicidas sobre las propiedades del suelo y sobre la comunidad de nematodos fue m��s agudo que el efecto de las enmiendas. La incorporaci��n de los restos de cosecha al final del ciclo de cultivo de la jud��a tuvo un gran efecto sobre la comunidad de nematodos, y aunque el n��mero total de nematodos increment�� al final del experimento, se observ�� una condici��n perturbada permanente de la red tr��fica ed��fica a lo largo del experimento. ABSTRACT Due to the uncertain future of the soil fumigants most commonly used in the EU, that might involve risks for human/animal health and the environment, there is a need to develop new integrated pest management programs, included as mandatory in the Regulation (EC) No. 1107/2009, to control crop diseases. According to this Regulation, evaluating the risk associated to the use of the plant production products (PPP) on non-target soil fauna and their function, and developing assays with different indicator species to obtain toxicity data to be used in the risk evaluation is mandatory. However, the low representativeness of some of these indicator species in the Mediterranean area is a relevant limitation. In this situation, the Scientific Panel of Plant Protection Products and their Residues of the European Food Safety Authority (EFSA) has pointed out the necessity of modifying the ecotoxicological data set required to evaluate non-target effects of PPP in a more integrated way, including structural and functional endpoints with organism such as bacteria, fungi, protists and nematodes. Thus, EFSA has recommended the use of nematodes in the assessment of the functional and structural features of the soil. Nematodes are globally distributed and morphologically diverse, and due to their high abundance and diversity of responses to soil disturbance, they are suitable indicators of the soil condition. Since nematodes interact with many other organisms as participants in several links of the soil food web, playing important roles in essential soil processes in agroecosystems, nematode diversity is often used as a biological indicator of the effects of agricultural practices on soil condition. In the last years, various indices based on soil nematode assemblages, have facilitated the interpretation of complex soil ecological data. Soil food web indices based on the abundances of functional guilds defined by C-P groups and trophic groups, permit evaluating soil food web functioning. On the other hand, the difficulty of nematode taxonomical identification is commonly argued to explain their limited used as ecological indicators, and there is a certain controversy in terms of the efficacy of various nematode identification methods. It is argued that the morphological identification is difficult and time consuming due to the lack of specialist knowledge, and it is claimed that molecular techniques can solve some limitations of morphological techniques such as the identification of juveniles. Nevertheless, molecular identification methods are limited too, since most of the DNA-based databases are strongly oriented towards plant-parasitic nematodes that represent only a fraction of the soil nematode community, while there is little information available on free-living nematodes, which represent most soil nematodes. This work focuses on the study of the effects of soil fumigants on soil functioning through the use of different indicators based on soil nematode community as soil food web indices, diversity indices, the abundance of more relevant taxa etc. Other functional indicators related to soil suppressiveness, nutrient cycling, or the activity of soil microfauna have been also studied. In chapter 1, nematode diversity assessed in a commercial strawberry farm and its surroundings for two consecutive growing seasons in southern Spain, was low in fumigated soils with chemical pesticides throughout both seasons and, although yearly recovery occurred within the treated fields, fumigated soils showed a permanent perturbed condition. The nematode community was more closely associated to nutrient cycling in the non-cropped than in the cropped soils, and the link between plant biomass and nematode community structure was weak. Non-treated furrows within the treated fields were a reservoir of both beneficial and plant-parasitic nematodes, but such difference between furrows and beds was not enough to maintain more suppressive soil assemblages in the furrows. Treated soils were less suppressive than unmanaged soils, and there was a positive and significant correlation between soil suppressiveness and soil food web structure and diversity. In chapter 2, the effects of two organic pesticides with nematicide effect and two chemical nematicides on soil physicalchemical properties, soil nematode diversity and plant biomass in experimental conditions were assessed in two types of soils: low diversity soils from an agricultural farm, and high diversity soils from a natural vegetation area. The larger effect was observed on the neem treatment, which induced a large boost of dauer juveniles in the nutrient-depleted soil, while the same treatment induced the increase of more stable, less opportunistic, populations of generalist bacterivore nematodes in the pine forest soil, rich in organic matter. In chapter 3, comparison of the efficiency of molecular (TRFLP, Terminal Restriction Fragment Length Polymorphism) and morphological (microscopy at high magnification) identification methods was carried out in different nematode communities from five sites of different land uses in Spain and Ireland. Differences and similarities on nematode diversity and other ecological and soil food web indices assessed by both methods, were statistically compared. Molecular identification with TRFLP only detected a percentage of the taxa present in the soil samples identified morphologically, and omnivores and predators were not detected molecularly in our study. Indices involving microbial feeding nematodes were more similar between identification methods than indices involving higher trophic links. Our results show that, at least with the technique used in this study, identifying nematodes morphologically is a reliable and more precise identification tool than molecular identification, since a higher taxonomic resolution is in general obtained compared to TRFLP. In chapter 4, the effect of chemical nematicides on nematode community descriptors and plant biomass was also studied in field conditions in an experimental area in which dazomet and dimethyl disulfide was applied in a bean-cabbage rotation system for a single season. Organic amendments were incorporated into the soil with the aim of mitigate the negative effect of the pesticides on soil diversity. The effect of the nematicides was much more noticeable than the effect of the amendments on soil properties and nematode community descriptors. The incorporation of bean crop residues into the soil at the end of bean crop cycle affected soil nematode community descriptors to a great extent, and although total number of nematodes increased at the end of the experiment, a permanent perturbed soil food web condition was observed along the experiment.

Effects of biochar prepared from organic waste on soil properties

Biochar is a carbon-rich solid obtained by the thermal decomposition of organic matter under a limited supply of oxygen and at relatively low temperatures. Biochar can be prepared from the pyrolysis of different organic feed- stocks, such as wood and biomass crops, agricultural by-products, different types of waste or paper industry waste materials . The pyrolysis procedure of waste, i.e. sewage sludge, has mainly two advantages, firstly, it removes pathogens from waste and, secondly, biochar can reduce the leaching of heavy metals present in raw sewage sludge. This trend of the use of waste material as feedstocks to the preparation of biochar is increasing in the last years due to industrial development and economic growth imply an increase in waste generation. The application of biochar may have positive effects on soil physical properties as water holding capacity and structure or on soil biological activity and soil quality. Also, biochar can be used to remove water pollutants and can be used in multiple ways in soil remediation due to its adsorption of pesticides or metals. Also, biochar contribute to carbon sequestration due to carbon stability of biochar materials. The objective of this presentation is to review the positive effects of the biochar prepared from organic waste on soil properties.

Ca-amendement and tillage: medium term synergies for improving key soil properties of acid soils. Soil and tillage research, 134: 195-206

Ca-amendments are routinely applied to improve acid soils, whilst no-tillage (NT) has been widely recommended in soils where traditional tillage (TT) has led to losses of organic matter. However, the potential interactions between the two treatments are only partially known. Our study was conducted on an annual forage crop agrosystem with a degraded Palexerult soil located in SW Spain, in order to assess if the combination of NT plus a Ca-amendment provides additional benefits to those of their separate use. To this end we analysed the effects of four different combinations of tillage and Ca-amendment on selected key soil properties, focusing on their relationships. The experimental design was a split-plot with four replicates. The main factor was tillage (NT versus TT) and the second factor was the application or not of a Ca-amendment, consisting of a mixture of sugar foam (SF) and red gypsum (RG). Soil samples were collected from 3 soil layers down to 50 cm after four years of treatment (2009). The use of the Ca-amendment improved pH and Al-toxicity down to 25 cm and increased exchangeable Ca2+ down to 50 cm, even under NT due to the combined effect of SF and RG. Both NT and the Ca-amendment had a beneficial effect on total organic carbon (TOC), especially on particulate organic carbon (POC), in the 0–5 cm layer, with the highest contents observed when both practices were combined. Unlike NT, the Ca-amendment failed to improve soil aggregation in spite of the carbon supplied. This carbon was not protected within the stable aggregates in the medium term, making it more susceptible to mineralization. We suggest that the fraction of Al extracted by oxalate from solid phase (AlOxa-Cu-K) and the glomalin-related soil proteins (GRSPs) are involved in the accumulation of carbon within water stable aggregates, probably through the formation of non-toxic stable Al-OM compounds, including those formed with GRSPs. NT alone decreased AlK in the 0–5 cm soil layer, possibly by increasing POC, TOC and GRSPs, which were observed to play a role in reducing Al toxicity. From our findings, the combination of NT and Ca-amendment appears to be the best management practice to improve chemical and physical characteristics of acid soils degraded by tillage.

Soil aggregate geometry: Measurements and morphology

Aggregates provide physical microenvironments for microorganisms, the vital actors of soil systems, and thus play a major role as both, an arena and a product of soil carbon stabilization and dynamics. The surface of an aggregate is what enables exchange of the materials and air and water fluxes between aggregate exterior and interior regions. We made use of 3D images from X-ray CT of aggregates and mathematical morphology to provide an exhaustive quantitative description of soil aggregate morphology that includes both intra-aggregate pore space structure and aggregate surface features. First, the evolution of Minkowski functionals (i.e. volume, boundary surface, curvature and connectivity) for successive dilations of the solid part of aggregates was investigated to quantify its 3D geometrical features. Second, the inner pore space was considered as the object of interest. We devised procedures (a) to define the ends of the accessible pores that are connected to the aggregate surface and (b) to separate accessible and inaccessible porosity. Geometrical Minkowski functionals of the intra-aggregate pore space provide the exhaustive characterization of the inner structure of the aggregates. Aggregates collected from two different soil treatments were analyzed to explore the utility of these morphological tools in capturing the impact on their morphology of two different soil managements, i.e. conventional tillage management, and native succession vegetation treatment. The quantitative tools of mathematical morphology distinguished differences in patterns of aggregate structure associated to the different soil managements.