Analysis of agricultural and forestry innovation in the European Union Thematic Networks and the innovative use of sewage sludge in silvopastoral systems soil

INTERNATIONAL DOCTORAL SCHOOL OF THE USC Darío Arias Martínez PhD Thesis Analysis of agricultural and forestry innovation in the European Union Thematic Networks and the innovative use of sewage sludge in silvopastoral systems soil Lugo, 2024 Doctoral Programme in Agricultural and Forestry Research DOCTORAL THESIS ANALYSIS OF AGRICULTURAL AND FORESTRY INNOVATION IN THE EUROPEAN UNION THEMATIC NETWORKS AND THE INNOVATIVE USE OF SEWAGE SLUDGE IN SILVOPASTORAL SYSTEMS SOIL Darío Arias Martínez Supervisors: María Rosa Mosquera Losada Antonio Rigueiro Rodríguez Tutor: María Rosa Mosquera Losada PHD PROGRAMME IN AGRICULTURAL AND FORESTRY RESEARCH LUGO 2024 A mis hijos, Hernán y Eva, causa y solución de mis verdaderas preocupaciones. Nada hay bajo el sol que no tenga solución, nunca una noche venció a un amanecer. Agradecimientos Son varias las personas que me han ayudado y animado desde que inicié este viaje, pero sin lugar a dudas la persona que más me ha ayudado a lo largo de todo este proceso y durante los últimos quince años ha sido mi mujer, Saray. Gracias por darme siempre un impulso cuando lo he necesitado, ser la luz en momentos de oscuridad y guía en momentos de incertidumbre. Al verdadero motor del departamento de Producción Vegetal y compañeros de trabajo durante cuatro años, Pablo, Divina, Teresa y Manuel, por vuestra labor indispensable. La investigación existe gracias a vosotros. A Nuria, Tamara, Pancho, Mercedes, Esther, Vanessa, Antía y Javier, por los días de trabajo en campo, en el laboratorio y en el despacho, por ayudarme a resolver dudas, por las correcciones, por los buenos momentos... A mis directores, Rosa y Antonio, por brindarme la oportunidad de embarcarme en esta larga aventura. A mis padres, mi hermano y mi hermana, porque aunque no lo dicen sé que se preocupan y transmiten su apoyo. A mis suegros, por abrir la guardería siempre que lo hemos necesitado. CONTENTS RESUMEN .................................................................................................................... I RESUMO ................................................................................................................. VII ABSTRACT ............................................................................................................ XIII 1. INTRODUCTION .................................................................................................... 1 1.1. Agricultural and forest innovation ..................................................................... 1 1.1.1. Importance of innovation ............................................................................ 1 1.1.2. The agricultural European Innovation Partnership (EIP-AGRI) ................ 2 1.2. Innovative soil management practices ............................................................... 3 1.2.1. Agroforestry practices ................................................................................. 3 1.2.2. Soil carbon sequestration in silvopastoral systems ..................................... 4 1.2.3. Circular economy and the use of sewage sludge waste .............................. 4 2. OBJECTIVES .......................................................................................................... 7 3. THE EIP-AGRI THEMATIC NETWORKS: FOSTERING INNOVATION IN EUROPE 9 3.1. Abstract ......................................................................................................... 9 3.2. Introduction ................................................................................................... 9 3.3. Material and methods ...................................................................................... 11 3.4. Results ............................................................................................................. 13 3.4.1. Land use and Location .............................................................................. 13 3.4.2. Farming type ............................................................................................. 15 3.4.3. Farm workers ............................................................................................ 15 3.4.4. Farm management ..................................................................................... 16 3.5. Discussion ........................................................................................................ 17 3.5.1. Policy implications .................................................................................... 19 3.6. Conclusions ..................................................................................................... 20 4. THEMATIC NETWORKS DATA ORIGIN AND THEIR SYNERGIES WITH OTHER EIP-AGRI INITIATIVES .......................................................................................... 21 4.1. Abstract ............................................................................................................ 21 4.2. Introduction...................................................................................................... 21 4.3. Material and methods .................................................................................. 23 - Arable crop ............................................................................................................... 25 - Permanent crop ........................................................................................................ 25 - Permanent grassland ................................................................................................ 25 II La innovación no se basa sólo en el descubrimiento sino también en la cooperación y el aprendizaje interactivo, lo que implica la optimización del intercambio y la explotación de los diversos recursos de una asociación de múltiples actores. Este proceso involucra a universidades y centros de investigación que generan la base de conocimientos para las innovaciones tecnológicas que respalden los sistemas agrícolas verdaderamente sostenibles y a formuladores de políticas que traducen estas innovaciones en normativas que los agricultores pueden adoptar fácilmente al aumentar su conciencia sobre las prácticas sostenibles. Por lo tanto, los agricultores necesitan tener acceso a información abundante y neutral difundida mediante datos confiables y orientación técnica adaptada a las condiciones locales para cumplir con los requisitos ambientales y sociales respaldados por la Política Agrícola Común (PAC). Por lo tanto, la transición desde la idea o necesidad inicial a la adopción de tecnologías efectivas debe estar respaldada por políticas e instituciones basadas en la innovación, la difusión de innovaciones y conocimientos para apuntalar el crecimiento, prestando atención a los procesos de aprendizaje y facilitando la imitación de tecnologías y disminuir las diferencias de productividad entre las regiones a partir de una sociedad informada que integre constantemente los avances científicos de diversas disciplinas de investigación. Sin embargo, frente a los desafíos globales como el cambio climático, la escasez de recursos y la inseguridad alimentaria, existe una necesidad creciente de enfoques más coordinados e innovadores. La UE tiene una larga historia de apoyo a la innovación agrícola y forestal a través de diversas políticas e iniciativas. En este sentido, la UE está promoviendo el desarrollo sostenible a través de la implementación de la Asociación Europea de Innovación Agrícola (AEI-AGRI), el establecimiento de la Asociación Europea de Agroecología Horizonte Europa y la integración del desarrollo del conocimiento y la innovación como clave para la Política Agrícola Común (PAC) Post 2020. El Pacto Verde Europeo y la Estrategia de la Granja a la Mesa, así como el décimo objetivo de la Política Agrícola Común 2023-2027, reconocen la importancia de los sistemas de conocimiento e innovación. La iniciativa AEI-AGRI se creó con el objetivo de fomentar la innovación en la agricultura, la silvicultura y el desarrollo rural y crear sinergias entre diferentes programas políticos tanto a nivel de la UE como de los Estados miembros fomentando el diálogo y la colaboración entre agricultores, silvicultores, asesores, investigadores, y cualquier otro actor relevante involucrado en el Sistema de Conocimiento e Innovación Agrícola (AKIS). Para aumentar la creación de redes y fortalecer el AKIS de la UE, la CE ha fusionado la AEI-AGRI con la Red Europea para el Desarrollo Rural (REDR) en la Red Europea de la PAC, cuyo objetivo es optimizar el flujo de información sobre agricultura y política rural dentro de la UE y apoyar la transición hacia un sector agrícola europeo sostenible, resiliente y moderno, impulsando y dirigiendo todos los aspectos de la implementación de la Política Agrícola Común de la UE. La versión más reciente de la PAC para el período 2023-2027 se basa en los propios planes estratégicos de los Estados miembros enmarcados en diez objetivos clave para ayudar a cada Estado miembro a ajustar mejor las intervenciones políticas a sus condiciones y necesidades locales. Las actividades de la AEI-AGRI se encuentran entre las Redes de Desarrollo Rural (segundo pilar de la PAC) y los anteriores programas de investigación Horizonte 2020 y el nuevo Horizonte Europa de la UE. Financian proyectos destinados a impulsar la innovación agrícola y abordar los desafíos a los que se enfrentan los agricultores y silvicultores a través de la PAC en los que investigadores y partes interesadas trabajan juntos para desarrollar III soluciones prácticas, con el apoyo activo de la AEI-AGRI, en forma de Redes Temáticas (RT) (Acciones Coordinadas de Apoyo) y Proyectos Multiactor (PMA) (Acciones de Investigación e Innovación). La AEI-AGRI también incluye los Grupos Operativos (GO), que tienen ámbito nacional, están financiados por varios tipos de Programas de Desarrollo Rural (PDR) del Pilar I de la antigua y actual PAC y fomentan la innovación a nivel agrícola en toda Europa. Desde el punto de vista de la investigación, los PMA de la AEI-AGRI tienen como objetivo fomentar la investigación y la innovación a través de la cocreación llevada a cabo por diferentes tipos de actores, incluidos agricultores e investigadores en diferentes niveles (local, regional o nacional). Para promover la agricultura y la silvicultura sostenibles, la UE invierte anualmente en proyectos a través de sus programas Horizonte con el fin de desarrollar y/o compartir de forma colaborativa soluciones innovadoras que sigan el enfoque multiactor. Un tipo de proyectos financiados por el Horizonte 2020 son las Redes Temáticas (RT), que son un tipo particular de proyectos multiactor que recopilan conocimientos existentes y las mejores prácticas sobre un tema determinado para ponerlos a disposición de los usuarios finales, como los agricultores, silvicultores, asesores y otros en formatos fácilmente comprensibles. Estas redes cubren una amplia gama de temas, desde prácticas agrícolas sostenibles y agricultura de precisión hasta gestión forestal y bioeconomía. El objetivo principal de las Redes Temáticas es recopilar, compartir y difundir conocimientos orientados a la práctica sobre un tema agrícola o forestal específico, proporcionando una plataforma para que las partes interesadas intercambien buenas prácticas, compartan resultados de investigaciones y desarrollen proyectos conjuntos para abordar desafíos comunes. Al reunir diversas perspectivas y conocimientos, las RT contribuyen al desarrollo y la implementación de soluciones innovadoras que pueden mejorar la competitividad y la sostenibilidad de los sectores agrícola y forestal de la UE. Las RT logran esto transformando el conocimiento en materiales que sean fácilmente comprensibles para sus usuarios finales: agricultores/silvicultores, formuladores de políticas y facilitadores tales como asesores o capacitadores. El ecosistema actual, compuesto por todas las bases de conocimiento sobre innovación desarrolladas en las RT, debería permitir sacar el máximo beneficio de las inversiones en innovación. Por otro lado, los Grupos Operativos (GO), que anteriormente estaban financiados por los Programas de Desarrollo Rural (PDR) y actualmente a través de los Planes Estratégicos nacionales de la PAC desarrollados en cada Estado miembro, tienen como objetivo reunir a múltiples actores como agricultores, investigadores, asesores, empresas, grupos ambientalistas, grupos de interés de consumidores u otras ONG para promover la innovación en los sectores agrícola y forestal abordando un problema u oportunidad específica a escala local, regional o nacional. Estos proyectos multiactor deben producir resúmenes de prácticas breves para describir sus planes y principales hallazgos. Los resúmenes de prácticas son definidos por la Comisión Europea como recomendaciones y soluciones breves e informativas y se crean siguiendo un formato común para traducir el conocimiento generado por Proyectos Multiactor, Redes Temáticas y Grupos Operativos en material fácilmente comprensible para los usuarios finales. Los resúmenes de prácticas aumentan la difusión de los proyectos y el intercambio de conocimientos a lo largo del ciclo de vida del proyecto, proporcionando resultados utilizables que facilitan la adopción de conocimientos por parte de agricultores y productores. Sin embargo, la evidencia es que gran parte del conocimiento útil generado en las RT no llega a los destinatarios previstos, principalmente a aquellos que no participan directamente en su creación. Como resultado, un número significativo de soluciones innovadoras recopiladas IV por las RT nunca se ponen en práctica, lo que reduce considerablemente el efecto previsto de las RT y provoca una fragmentación del panorama de innovación agrícola y forestal de la UE. Además, organizaciones e individuos de toda la UE y países asociados pueden participar en proyectos AEI-AGRI y Horizonte 2020, creando un ecosistema colaborativo que enriquece la creación de conocimiento en aquellos campos que necesitan soluciones o mejoras y que son directamente aplicables por los usuarios finales. Sin embargo, la participación puede estar distribuida de manera desigual, con una tendencia general de correlación entre el nivel de desarrollo y la capacidad de atraer fondos y proyectos. Los vínculos entre las iniciativas tampoco están claros, y es necesario desarrollar conexiones sistemáticas para mejorar las sinergias en el panorama AEI-AGRI a fin de evitar la duplicación de esfuerzos y la pérdida de oportunidades de colaboración. Por lo tanto, las Redes Temáticas del Horizonte 2020 ponen a disposición de los usuarios finales conocimientos y buenas prácticas agrícolas y forestales listas para ser implementadas y basadas en la investigación. El estudio de este tipo de proyectos multiactor permite conocer qué temas se tratan en mayor número, posibilitando un mayor intercambio de conocimientos entre agricultores, investigadores y asesores con el fin de promover el uso de prácticas más sostenibles, efectivas y competitivas. El alcance de las Redes Temáticas se analizó para conocer cuáles son sus principales temas y destinatarios en términos de usos del suelo y ubicación y los tipos de explotación, trabajadores y gestión involucrados, con el fin de conocer cuáles son los temas preferidos por los investigadores y los menos tratados y, por lo tanto, con una mayor necesidad de investigación e implementación de innovación. Además, se evaluó la participación de los diferentes países en las RT, ya sea como coordinadores o como socios, así como los materiales producidos y sus fuentes de información y la forma en que establecieron sinergias con otras iniciativas. Nuestros hallazgos revelan que las RT se dirigieron principalmente a tierras cultivables, que necesitan más innovación y a todo tipo de tipologías agrícolas relevantes (pequeñas/grandes, granjas familiares/cooperativas, convencionales/ecológicas). Sin embargo, se debe prestar más atención a las prácticas sostenibles vinculadas a las cadenas de valor/bioeconomía/economía circular y también a los diferentes tipos de uso de la tierra, tales como la agroforestería y las relacionadas con áreas menos favorecidas o tierras marginales. La participación entre los países de la UE fue desigual, principalmente debido a las diferencias en la proporción de tierra destinada a los diferentes tipos de agricultura, en la investigación, desarrollo y transferencia y en el desarrollo y transferencia de la innovación. El mantenimiento e incremento de los documentos de innovación pueden aumentar la sostenibilidad de los sistemas agrícolas y forestales, así como las redes de innovación entre los actores y el fomento de la participación de los agricultores en los proyectos. La relación entre investigadores y profesionales puede promoverse mediante los vínculos entre las RT con los GO y las RRN. La participación de actores relevantes podría promover la difusión de medidas de innovación, facilitando la transferencia de conocimientos mediante una comunicación efectiva para llegar a una audiencia más amplia y mayor. Un ejemplo de este tipo de prácticas sostenibles son los sistemas agroforestales. Los sistemas agroforestales son reconocidos como un enfoque integrado para el uso sostenible del suelo debido a la incorporación de árboles o arbustos en tierras de cultivo o pastos en una misma superficie y en interacción. Estos sistemas son una buena herramienta para el secuestro de carbono mediante la absorción del dióxido de carbono que se encuentra en la atmósfera y su fijación en el suelo, constituyendo un elemento clave para alcanzar los objetivos marcados por el protocolo de Kioto en 2005, ayudando a mitigar los efectos del cambio climático. V Los sistemas agroforestales son eficaces sumideros de C cuando se diseñan y gestionan adecuadamente, ya que pueden contribuir a depósitos de C por encima y por debajo del suelo con un mayor potencial para secuestrar C que los pastos o cultivos extensivos que crecen en condiciones ecológicas similares. Además, los árboles retienen mucho más carbono por unidad de superficie que otros tipos de vegetación, porque aportan materia orgánica al suelo, tanto en forma de hojarasca y residuos en la superficie como de raíces muertas y exudados en las profundidades del suelo, lo que aumenta las existencias de carbono orgánico del suelo (COS). Dado que el COS controla la fertilidad del suelo, puede utilizarse como indicador de la salud del suelo. Un aumento en la reserva de COS disminuye los riesgos de erosión del suelo y la contaminación de fuentes difusas y mejora la calidad del agua. Sin embargo, los cambios en las reservas y la dinámica del COS pueden modificar la transferencia de C a otros compartimentos ambientales, como la hidrosfera y la atmósfera, siendo importante una gestión adecuada del suelo para mitigar el cambio climático, como la que promueven los sistemas agroforestales como señala la Estrategia de la Granja a la Mesa y la Nueva Estrategia Forestal de la UE para 2030. Más del 80% del carbono terrestre está supuestamente en el suelo, lo que lo convierte en la mayor reserva terrestre de carbono orgánico, principalmente porque el suelo es el destino final de la gran mayoría del C fotosintético fijado en los ecosistemas terrestres, capturando aproximadamente el 20% del carbono emitido anualmente a la atmósfera como resultado de las actividades humanas. Por lo tanto, pequeños cambios en las reservas de COS pueden afectar significativamente las concentraciones de dióxido de carbono atmosférico y la gestión del COS podría desempeñar un papel importante en la mitigación del cambio climático. El C se almacena en el suelo vinculado a diferentes fracciones de tamaño del suelo, con un tiempo de residencia medio en cada fracción que varía de 1 a 10 años en macroagregados (250–2000 µm), de 1 a 25 años en microagregados (53–250 µm) y de 100 a 1.000 años en las fracciones limo + arcilla (<53 µm), aunque el secuestro depende del manejo de la tierra, factores edáficos y climáticos y la cantidad y calidad de los insumos vegetales y microbianos. Los árboles cultivados en un sistema silvopastoral contribuyen a la mayor parte del COS asociado a las fracciones finas de limo + arcilla hasta 1 m de profundidad y las raíces profundas pueden actuar como un sumidero de C más confiable y a más largo plazo a pesar de renovarse más lentamente y tener una densidad menor que las raíces poco profundas. Los nogales, de raíces pivotantes y profundas, han sido ampliamente utilizados en sistemas agroforestales, principalmente en sistemas silvoarables, debido a su interés económico basado en la producción de frutos para consumo humano y su madera de fácil mecanización. Esta especie de árbol responde con alta plasticidad a la heterogeneidad de las condiciones del suelo promovida por la competencia con cultivos intercalados, lo que obliga a las raíces de los árboles a explorar y alcanzar capas más profundas y, por lo tanto, aumentar el potencial secuestro de C en las capas profundas del suelo. La adición de lodos de depuradora procedentes de depuradoras de aguas, uno de los principales residuos de las comunidades urbanas, constituye una fuente de elementos nutrientes, especialmente N y P, así como de materia orgánica, al mismo tiempo que mejora las cualidades del suelo. El uso de lodos de depuradora como fertilizante mejora el crecimiento de la vegetación y el secuestro de carbono, lo que es de especial relevancia en Galicia (noroeste de España) debido a la baja fertilidad del suelo como consecuencia del aumento de la acidez, que reduce la productividad de los pastos y los árboles, al mismo tiempo que encaja en el concepto de economía circular como un proceso de reciclaje de residuos y le aporta un valor añadido. VI La fertilización con lodos de depuradora en sistemas agroforestales promueve la mineralización de C y los depósitos de N inorgánico, lo que conduce a una mayor disponibilidad de nutrientes para las plantas y una mayor productividad de los cultivos, reduciendo la competencia entre cultivos agrícolas y árboles, y haciendo que los sistemas sean más viables y sostenibles económicamente debido a la reducción de los costes anuales de los fertilizantes inorgánicos, añadido al hecho de que la presencia de árboles en las tierras de cultivo mejora el estado de nutrientes del suelo y reduce la necesidad de insumos externos de fertilizantes. Sin embargo, los lodos de depuradora deben ser tratados antes de su uso en agricultura para reducir significativamente su fermentabilidad y los riesgos para la salud derivados de su uso, existiendo varios métodos como la digestión anaeróbica, el compostaje y la peletización, que pueden diferir en la concentración final de metales pesados y contenido de agua, así como en la proporción de las diferentes fracciones de agregados del suelo y su estabilidad, lo que resulta en diferencias en la protección del carbono orgánico. El uso de lodos de depuradora debe cumplir con regulaciones específicas europeas y de sus Estados miembros, que establecen los límites de aplicación de varios metales pesados, la necesidad de tratamiento de lodos antes de su uso en agricultura y la prohibición de su uso en algunos tipos de cultivos a menos que haya transcurrido un cierto período de tiempo, siempre teniendo en cuenta las necesidades de nutrientes de las plantas y el pH del suelo para evitar daños al suelo, al agua, a la cubierta vegetal y a la salud humana y animal. El efecto de diferentes tipos de lodos de depuradora (anaeróbicos, compostados y peletizados) fue evaluado sobre los efectos en las propiedades químicas (pH) y físicas del suelo, el almacenamiento de carbono en el suelo total y en cada fracción de agregado del suelo, el crecimiento de los árboles y en la producción de pasto en comparación con tratamientos control (sin fertilización y fertilización mineral) en un sistema silvopastoral establecido bajo Juglans regia L. para evaluar la capacidad real de almacenamiento en el suelo que tienen estos sistemas, aportando un enfoque bioeconómico mediante la revalorización de los residuos urbanos. Se descubrió que las enmiendas orgánicas pueden aumentar el pH del suelo, especialmente cuando los valores iniciales son bajos, fomentando una mayor tasa de mineralización de la materia orgánica y en consecuencia disminuyendo la concentración y el almacenamiento de C en el suelo total, afectando de manera diferente las propiedades del suelo dependiendo de la composición de los tratamientos de fertilización aplicados. El efecto de la fertilización con lodos de depuradora dura pocos años, siendo aconsejable realizar tratamientos periódicos para favorecer el crecimiento de pastos y árboles al mismo tiempo que se reciclan materiales de desecho. VII RESUMO A innovación en todos os sectores económicos constitúe unha fonte de coñecemento para o desenvolvemento e mellora das novas tecnoloxías e metodoloxías. Foi descrito pola Organización das Nacións Unidas para a Agricultura e a Alimentación (FAO) como un proceso polo cal individuos ou organizacións poñen en uso produtos, procesos ou formas de organización novos ou existentes por primeira vez nun contexto específico para aumentar a eficacia competitividade e resistencia para resolver un problema. Na maioría dos casos procede da investigación, que normalmente se apoia con financiamento público, o que permite transformar ideas en coñecemento axeitado para xurdir como tecnoloxías aplicables en moitos ámbitos diferentes. Máis concretamente, a innovación agrícola é definida polo Foro Global de Servizos de Asesoramento Rural como unha rede de organizacións, empresas e individuos centrada en levar novos produtos, novos procesos e novas formas de organizacións ao uso social e económico, xunto coas institucións e políticas que afectan o seu comportamento e rendemento innovadores. Este sistema interactivo está formado por persoas e organizacións que demandan e proporcionan coñecemento, así como as políticas e mecanismos que afectan á forma en que os diferentes axentes interactúan para compartir, acceder e intercambiar coñecementos. Ademais, a FAO indica que a innovación agrícola axuda a aumentar a seguridade alimentaria, o desenvolvemento sostible e promover o desenvolvemento rural para lograr un mundo libre de fame e desnutrición. Desde o punto de vista ambiental, a investigación e a innovación nos sectores agrícola e forestal é fundamental para previr a perda de biodiversidade e os efectos do cambio climático, contribuíndo á evolución dos sistemas agrícolas adaptados ás necesidades específicas e ao desenvolvemento sostible da Unión Europea (UE) e os seus estados membros. Ademais, o desenvolvemento da innovación na agricultura é clave para avanzar na implementación dos últimos resultados da investigación a nivel de explotacións. Isto é especialmente relevante para os produtores primarios, que teñen unha necesidade particular de servizos de asesoramento obxectivos e personalizados sobre opcións de xestión sostible para adaptar os seus sistemas de produción para que sexan máis sostibles ante as condicións cambiantes do clima e do solo. A investigación agrícola e forestal fixo importantes avances para fomentar a sustentabilidade nas últimas décadas. Non obstante, as metodoloxías actualizadas aínda non se están aplicando totalmente no campo, dependendo das prácticas de cultivo intensivo levadas a cabo na UE durante o século pasado. A Comisión Europea (CE) é consciente da necesidade de fomentar a innovación na agricultura na UE, onde os solos se viron moi afectados por prácticas agrícolas insostibles, a biodiversidade reduciuse e o clima se viu afectado negativamente. Como resultado, a adopción da agricultura ecolóxica aumentou significativamente en Europa nos últimos anos debido á preocupación pública e a UE fixou unha redución do uso de pesticidas nun 50% para 2030 como parte dos seus obxectivos do Pacto Verde. Non obstante, a transición dos sistemas de cultivo intensivo cara a sistemas agrícolas vinculados a prácticas baseadas na natureza avanza lentamente, debido principalmente á falta de coñecemento e organización eficiente para acceder a eles, programas educativos, desenvolvemento de prácticas sostibles, redes sociais da granxa á mesa e cadeas de valor, así como infraestruturas e políticas adecuadas para promover a sustentabilidade a longo prazo. VIII Con todo, a innovación non se basea só no descubrimento, senón tamén na cooperación e na aprendizaxe interactiva, que implica a optimización da posta en común e da explotación dos diversos recursos dunha asociación multiactor. Neste proceso participan universidades e centros de investigación que xeran a base de coñecemento para innovacións tecnolóxicas que apoien sistemas agrícolas verdadeiramente sostibles, e responsables políticos que traducen estas innovacións en normativas que os agricultores poden adoptar facilmente aumentando a conciencia dos agricultores sobre as prácticas sostibles. Polo tanto, os agricultores deben ter acceso a unha información abundante e neutral difundida mediante datos fiables e orientacións técnicas adaptadas ás condicións locais para cumprir cos requisitos ambientais e sociais apoiados pola Política Agraria Común (PAC). Polo tanto, a transición da idea ou necesidade inicial á adopción de tecnoloxías eficaces ten que ser apoiada por políticas e institucións baseadas na innovación, difundindo innovacións e coñecementos para sustentar o crecemento prestando atención aos procesos de aprendizaxe e facilitando a imitación das tecnoloxías e diminuír as diferenzas de produtividade entre as rexións a partir dunha sociedade informada que integra constantemente os avances científicos de diversas disciplinas de investigación. Non obstante, ante os desafíos globais como o cambio climático, a escaseza de recursos e a inseguridade alimentaria, hai unha necesidade crecente de enfoques máis coordinados e innovadores. A UE ten unha longa historia de apoio á innovación agrícola e forestal a través de diversas políticas e iniciativas. Neste sentido, a UE está a promover o desenvolvemento da sustentabilidade mediante a implementación da Asociación Europea de Innovación Agrícola (AEI-AGRI), o establecemento da Asociación Europea de Agroecoloxía Horizonte Europa e a integración do coñecemento e o desenvolvemento da innovación como clave para a Política Agraria Común Post 2020. O Pacto Verde Europeo e a Estratexia da Granxa á Mesa, así como o décimo obxectivo da Política Agrícola Común (PAC) 2023-2027 recoñecen a importancia dos sistemas de coñecemento e innovación. A iniciativa AEI-AGRI creouse co obxectivo de fomentar a innovación na agricultura, a silvicultura e o desenvolvemento rural e de crear sinerxías entre os diferentes programas políticos tanto a nivel da UE como dos Estados membros, fomentando o diálogo e a colaboración entre agricultores, silvicultores, asesores, investigadores e calquera outro actor relevante implicado no Sistema de Coñecemento e Innovación Agraria (AKIS) . Para mellorar o traballo en rede e reforzar os AKIS da UE, a CE fusionou o AEI-AGRI coa Rede Europea para o Desenvolvemento Rural (REDR) na Rede da UE da PAC, que ten como obxectivo optimizar o fluxo de información sobre a agricultura e a política rural dentro da UE e apoiar a transición cara a un sector agrícola europeo sostible, resiliente e moderno, impulsando e dirixindo todos os aspectos da aplicación da Política Agrícola Común da UE. A versión máis recente da PAC para o período 2023-2027 baséase nos propios plans estratéxicos dos Estados membros enmarcados en 10 obxectivos fundamentais para axudar a cada Estado membro a axustar mellor as intervencións políticas ás súas condicións e necesidades locais. As actividades do AEI-AGRI sitúanse entre as redes de desenvolvemento rural (2º pilar da PAC) e os anteriores programas de investigación Horizonte 2020 e os novos Horizonte Europa da UE. Financian proxectos destinados a impulsar a innovación agrícola e abordar os retos aos que se enfrontan agricultores e silvicultores a través da PAC nos que investigadores e partes interesadas traballan xuntos para desenvolver solucións prácticas, apoiadas activamente polo AEI-AGRI, en forma de Redes Temáticas (RT) (Accións Coordinadas de Apoio) e Proxectos Multiactor (PMA) (Accións de Investigación e Innovación). O AEI-AGRI tamén inclúe os Grupos Operativos (GO), que teñen ámbito nacional, están financiados por IX varios tipos de Programas de Desenvolvemento Rural (PDR) do Pilar I da PAC anterior e actual e fomentan a innovación a nivel de explotacións en toda Europa. Desde o lado da investigación, os PMA da AEI-AGRI pretenden fomentar a investigación e a innovación a través da co-creación realizada por diferentes tipos de actores, incluíndo agricultores e investigadores de diferentes niveis (local, rexional ou nacional). Para promover a agricultura e a silvicultura sostibles, a UE inviste anualmente en proxectos a través dos seus programas Horizon co fin de desenvolver e/ou compartir de forma colaborativa solucións innovadoras que sigan o enfoque multiactor. Un tipo de proxectos financiados polo Horizonte 2020 son as Redes Temáticas (RT), que son un tipo particular de proxectos multiactor que recollen coñecementos existentes e mellores prácticas sobre un tema determinado para facelo dispoñible en formatos facilmente comprensibles para os usuarios finais, como os agricultores, silvicultores, asesores e outros. Estas redes cobren unha ampla gama de temas, desde prácticas agrícolas sostibles e agricultura de precisión ata xestión forestal e bioeconomía. O obxectivo principal das Redes Temáticas é recoller, compartir e difundir coñecementos orientados á práctica sobre un tema específico da agricultura ou a silvicultura, proporcionando unha plataforma para que os interesados intercambien mellores prácticas, compartan resultados de investigación e desenvolvan proxectos conxuntos para abordar desafíos comúns. Ao reunir diversas perspectivas e coñecementos, as RT contribúen ao desenvolvemento e implementación de solucións innovadoras que poidan mellorar a competitividade e a sustentabilidade dos sectores agrícola e forestal da UE. As RT conseguen isto transformando o coñecemento en materiais facilmente comprensibles para os seus usuarios finais: agricultores/silvicultores, responsables políticos e facilitadores como asesores ou formadores. O ecosistema actual, composto por todas as bases de coñecemento sobre innovación desenvolvidas nas RT, debería permitir sacar o máximo proveito dos investimentos en innovación. Por outra banda, os Grupos Operativos (GO), que antes estaban financiados polos Programas de Desenvolvemento Rural (PDR) e actualmente a través dos Plans Estratéxicos nacionais da PAC desenvolvidos en cada Estado membro, pretenden reunir a múltiples actores como agricultores, investigadores, asesores, empresas, grupos ecoloxistas, grupos de interese de consumidores ou outras ONG para avanzar na innovación nos sectores agrícola e forestal abordando un problema ou oportunidade específica a escala local, rexional ou nacional. Estes proxectos multiactores están obrigados a producir resumos de prácticas curtos para esbozar os seus plans e as principais conclusións. Os resumos de prácticas son definidos pola Comisión Europea como recomendacións e solucións breves e informativas e créanse seguindo un formato común para traducir o coñecemento xerado por proxectos multiactor, Redes Temáticas e Grupos Operativos en material facilmente comprensible para os usuarios finais. Os resumos de prácticas aumentan a difusión dos proxectos e o intercambio de coñecemento ao longo do ciclo de vida do proxecto, proporcionando resultados útiles que facilitan a captación de coñecemento por parte dos agricultores e produtores. Porén, a evidencia é que gran parte do coñecemento útil xerado nas RT non chega aos destinatarios previstos, principalmente os que non están directamente implicados na súa creación. Como resultado, un número importante de solucións innovadoras recollidas polas RT nunca se poñen en práctica, o que reduce considerablemente o efecto previsto das RT e provoca unha fragmentación do panorama de innovación agrícola e forestal da UE . Ademais, organizacións e persoas de toda a UE e dos países asociados poden participar nos proxectos AEI-AGRI e Horizonte 2020, creando un ecosistema colaborativo que enriqueza a creación de coñecemento naqueles campos que precisan solucións ou melloras e X que son directamente aplicables polos usuarios finais. Non obstante, a participación pode estar distribuída de forma desigual, cunha tendencia xeral de correlación entre o nivel de desenvolvemento e a capacidade de captación de fondos e proxectos. Os vínculos entre as iniciativas tampouco están claros, polo que se precisa un desenvolvemento de conexións sistemáticas para mellorar as sinerxías no panorama AEI-AGRI para evitar a duplicación de esforzos e a perda de oportunidades de colaboración. Por iso, as Redes Temáticas do Horizonte 2020 poñen a disposición dos usuarios finais coñecementos e boas prácticas agrícolas e forestais listas para ser implementadas e baseadas na investigación. O estudo deste tipo de proxectos multiactor permite coñecer cales son os temas que se tratan en maior número, posibilitando un maior intercambio de coñecemento entre agricultores, investigadores e asesores para favorecer o uso de prácticas máis sostibles, eficaces e competitivas. O alcance das Redes Temáticas analizouse para coñecer cales son os seus principais temas e destinatarios en termos de usos do solo e localización e os tipos de explotación, traballadores e xestión involucrados, co fin de coñecer cales son os temas preferidos polos investigadores e os menos tratados e, por tanto, cunha maior necesidade de investigación e implementación de innovación. Ademais, avaliouse a participación dos diferentes países nas RT, xa sexa como coordinadores ou como socios, así como os materiais producidos e as súas fontes de información e a forma en que estableceron sinerxias con outras iniciativas. Os nosos descubrimentos revelan que as RT dirixíronse principalmente ás terras de cultivo, que precisan de máis innovación e a todo tipo de tipoloxías de explotacións relevantes (pequenas/grandes, explotacións familiares/cooperativas, convencionais/ecolóxicas). Non obstante, débese prestar máis atención ás prácticas sostibles vinculadas ás cadeas de valor/bioeconomía/economía circular e tamén a diferentes tipos de usos do solo como ao agroforestal e as relacionadas con zonas menos favorecidas ou terras marxinais. A participación entre os países da UE foi desigual, principalmente debido ás diferenzas na proporción de terra destinada aos diferentes tipos de cultivo, na investigación, desenvolvemento e transferencia e no desenvolvemento e transferencia da innovación. O mantemento e o aumento dos documentos de innovación pode aumentar a sustentabilidade nos sistemas agrícolas e forestais, así como as redes de innovación entre os actores e o fomento da implicación dos agricultores nos proxectos. A relación entre investigadores e profesionais pode ser promovida polos vínculos entre as RT co GO e as RRN. A participación de actores relevantes podería promover a difusión de medidas de innovación, facilitando a transferencia de coñecementos mediante unha comunicación efectiva para chegar a unha audiencia máis ampla e maior. Un exemplo deste tipo de prácticas sostibles son os sistemas agroforestais. Os sistemas agroforestais son recoñecidos como un enfoque integrado para o uso sostible da terra pola incorporación de árbores ou arbustos en terras de cultivo ou pastos nunha mesma superficie e en interacción. Estes sistemas son unha boa ferramenta para o secuestro de carbono mediante a absorción do dióxido de carbono que se atopa na atmosfera e a súa fixación no solo, constituíndo un elemento clave para acadar os obxectivos marcados polo protocolo de Kioto en 2005, contribuíndo a mitigar os efectos do cambio climático. . Os sistemas agroforestais son eficaces sumidoiros de C cando se deseñan e xestionan adecuadamente, xa que poden contribuír aos depósitos de C por encima e por baixo do chan cun maior potencial para secuestrar C que os pastos ou cultivos extensivos que crecen en condicións ecolóxicas similares. Ademais, as árbores conteñen moito máis carbono por unidade de superficie que outros tipos de vexetación, porque achegan materia orgánica ao XI solo, tanto en forma de follaxe e residuos na superficie como de raíces mortas e exudados nas profundidades do chan, o que aumenta as existencias do carbono orgánico do solo (COS). Dado que o COS controla a fertilidade do solo, pódese usar como un indicador da saúde do solo. Un aumento nas reservas do COS diminúe os riscos de erosión do chan e contaminación de fontes difusas e mellora a calidade da auga. Non obstante, os cambios nas reservas e a dinámica do COS poden modificar a transferencia de C a outros compartimentos ambientais, como a hidrosfera e a atmosfera, sendo unha xestión adecuada do solo importante para mitigar o cambio climático, como a que promoven os sistemas agroforestais como sinala a Estratexia da Granxa á Mesa e a Nova Estratexia Forestal da UE para 2030. Más do 80% do carbono terrestre está supostamente no chan, o que o converte na maior reserva terrestre de carbono orgánico, principalmente porque o chan é o destino final da gran maioría do C fotosintético fixado nos ecosistemas terrestres, capturando aproximadamente o 20% do carbono emitido anualmente á atmosfera como resultado das actividades humanas. Por tanto, pequenos cambios nas reservas de COS poden afectar significativamente as concentracións de dióxido de carbono atmosférico e a xestión do COS podería desempeñar un papel importante na mitigación do cambio climático. O C almacénase no solo ligado a diferentes fraccións do tamaño do solo, cun tempo medio de residencia en cada fracción que varía de 1 a 10 anos en macroagregados (250-2.000 µm), de 1 a 25 anos en microagregados (53-250 µm) e de 100 a 1.000 anos en fraccións limo + arxila (<53 µm), aínda que o secuestro depende do manexo da terra, factores edáficos e climáticos e a cantidade e calidade dos insumos vexetais e microbianos. As árbores cultivadas nun sistema silvopastoral contribúen á maior parte do COS asociado ás fraccións finas de limo + arxila ata 1 m de profundidade e as raíces profundas poden actuar como un sumidoiro de C máis confiable e a máis longo prazo a pesar de renovarse máis lentamente e ter unha densidade menor que as raíces pouco profundas. As nogueiras, de raíces pivotantes e profundas, foron amplamente utilizados en sistemas agroforestais, principalmente en sistemas silvoarables, debido ao seu interese económico baseado na produción de froitos para consumo humano e a súa madeira de fácil mecanización. Esta especie de árbore responde con alta plasticidade á heteroxeneidade das condicións do chan promovida pola competencia con cultivos intercalados, o que obriga ás raíces das árbores a explorar e alcanzar capas máis profundas e, por tanto, aumentar o potencial secuestro de C nas capas profundas do chan. A adición de lodos de depuradora procedentes de depuradoras de augas, un dos principais residuos das comunidades urbanas, constitúe unha fonte de elementos nutrientes, especialmente N e P, así como de materia orgánica, ao mesmo tempo que mellora as calidades do solo. O uso de lodos de depuradora como fertilizante mellora o crecemento da vexetación e o secuestro de carbono, o que é de especial relevancia en Galicia (noroeste de España) debido á baixa fertilidade do solo como consecuencia do aumento da acidez, que reduce a produtividade dos pastos e as árbores, ao mesmo tempo que encaixa no concepto de economía circular como un proceso de reciclaxe de residuos e achégalle un valor engadido. A fertilización con lodos de depuradora en sistemas agroforestais promove a mineralización de C e os depósitos de N inorgánico, o que conduce a unha maior dispoñibilidade de nutrientes para as plantas e unha maior produtividade dos cultivos, reducindo a competencia entre cultivos agrícolas e árbores, e facendo que os sistemas sexan máis viables e sostibles economicamente debido á redución dos custos anuais dos fertilizantes inorgánicos, engadido ao feito de que a presenza de árbores nas terras de cultivo mellora o estado de nutrientes do solo e reduce a necesidade de insumos externos de fertilizantes. XVIII sewage sludge fertilization lasts for few years, being advisable to carry out periodic treatments to promote pasture and tree growth at the same time waste materials are recycled. 1. INTRODUCTION 1.1. AGRICULTURAL AND FOREST INNOVATION 1.1.1. Importance of innovation In Europe, significant ecosystems are being lost or degraded as a result of the anthropogenic activity, with climate change being one of the most important pressures that lead to this situation (European Commission, 2021a, 2015a). Currently, 33% of the EU land is in a moderate to highly degraded state due to different processes of modification of soil conditions such as erosion, salinization, compaction, acidification, chemical contamination, deforestation and global warming (FAO, 2015). Moreover, greater losses of soils productive capacity could seriously harm food production and its security, increase volatility in food prices and lead millions of people around the world to hunger and poverty (FAO, 2015). One of the main contributors to climate change is current agricultural practices (IPCC, 2018) that have been carried out during the last century. These practices are unsustainable either because of the high resources consumption and the large emissions of the main greenhouse gases: carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) (Paustian et al., 2016), representing 10% of the European emissions. At the same time, agricultural producers are also affected by climate change that increases average maximum temperatures, extreme weather events frequency and the intraand interannual weather variability (Cradock-Henry et al., 2020). Moreover, these scenarios affect soils as a particularly vulnerable resource, whose functions are essential indicators of land productivity (European Commission, 2012a). However, soil degradation and climate change impacts can be reverted if sustainable land use based on scientific knowledge and the use of proven and evidence-based technologies and approaches is employed (FAO, 2015). The European Green Deal aims at transforming the EU into a fair and prosperous society, with a modern, resource-efficient and competitive economy where there are no net emissions of greenhouse gases in 2050 and where economic growth is decoupled from resource use. At the same time, the Green Deal contributes to the implementation of the United Nation’s 2030 Agenda and the Sustainable Development Goals (European Commission, 2019a) objectives aiming to eradicate poverty, protect the planet and ensure prosperity for all within a new sustainable development agenda (United Nations, 2017) for the 2015-2030 horizon. At the heart of the European Green Deal, the Farm to Fork Strategy will strengthen its efforts to tackle climate change, protect the environment and preserve biodiversity (European Commission, 2019a). The Farm to Fork Strategy puts Sustainable Development Goals in force by including all food chain actors to make the best use of nature-based, technological, digital, and space-based solutions to enhance ecosystem services delivery, increase climate resilience and reduce and optimize the use of resources (European Commission, 2020a). The transition towards a more sustainable production model is facilitated through innovation, defined by FAO (2020) as the process by which individuals or organizations put products, processes or forms of organization to use for the first time in a specific context with the aim of increasing efficiency, competitiveness and resilience to solve a problem, covering the entire agricultural, forestry or livestock production cycle and the entire value chain. Thus, innovation promotes the adoption of environmentally friendly agricultural and forestry practices based on the available knowledge obtained from the research but also based on already existing farming practices. In other words, innovation is the introduction of something new that returns an economic, social or environmental benefit for rural practice (EIP-AGRI, 2020a). However, long time is usually needed for practices to be adopted by farmers, mainly DARÍO ARIAS MARTÍNEZ 2 due to the lack of adequate extension and scientific services to transfer knowledge, being farmers who receive insufficient, obsolete, irrelevant and/or incorrect information (Concu et al., 2020; European Commission, 2012a). Fostering innovation also needs to create networks of interpersonal contacts among farmers and different types of actors to promote mutual learning and decision-making as they are considered the main sources of knowledge (Skaalsveen et al., 2020). According to Concu et al. (2020), there are several causes explaining the low adoption rates of innovation in agriculture. These can be organized into three main topics: 1. Policy-related barriers, such as lack of political commitment, little horizontal and/or vertical cooperation and an inadequate interface between science and policymaking, 2. Barriers related to farmers' perceptions, attitudes and beliefs about an innovation or conservation practice, 3. Technical and economic barriers that limit the rate of adoption of conservation practices. At a European level, the European Innovation Partnership for Agricultural productivity and Sustainability (EIP-AGRI) brings together all actors in agricultural and forestry innovation (farmers, advisors, researchers, companies, NGOs and others) to establish a broad network of European innovation to foster climate friendly practices across Europe. 1.1.2. The agricultural European Innovation Partnership (EIP-AGRI) In 2012 the European Commission created the European Innovation Partnership for Agricultural productivity and Sustainability (EIP-AGRI) to contribute to the European Union ‘Europe 2020’ strategy for smart, sustainable and inclusive growth (EIP-AGRI, 2020b), working to establish a link between science and the application of innovative approaches in practice and focusing not only on primary production but also on interactions between the supply chain and the consumer (European Commission, 2012a). Within the EIP-AGRI there are two types of policies that complement each other and finance projects with innovative ideas: the Rural Development Plans (RDPs) and the research and innovation programs of the ‘Horizon 2020’ program. These differ among other aspects in the territorial scope. On the one hand, RDPs finance Operational Groups, which are normally applied in a specific region or country and are based on a project where multiple actors interact. Operational Groups deal with a problem or opportunity that can lead to an innovation and contribute to achieving the established objectives, making use of different types of knowledge in an interactive way. They are made up of those key actors who are in the best position to achieve the project's objectives (farmers, researchers, consultants, companies, environmental groups, NGOs, etc.), share implementation experiences and disseminate the results on a large scale (EIP-AGRI, 2020c). Horizon 2020 was the largest source of funding for research and innovation in the European Union (€75 billion over a seven-year programme), only surpassed by the current Horizon Europe (€95.5 billion also for a seven year programme). The Horizon Europe objective was to create solutions to the problems currently encountered by farmers and foresters, dedicating 35 % of the funding to research related to climate, including adaptation, and addressing areas of knowledge with deficiencies (European Environment Agency, 2017) to boost smart, sustainable and inclusive growth by increasing excellence in the science base, promoting competitiveness and industrial leadership, and tackling societal challenges (European Commission, 2012b). This line of financing subsidizes a type of projects in which researchers and farmers, among other types of actors, find solutions together. They are called INTRODUCTION 3 Multi-actor Projects. Within these there is a particular type of projects, the Thematic Networks, in which the greatest effort is put into collecting and sharing knowledge and good practices that are ready to be put into practice and made all this knowledge accessible in formats that are easily understandable by end-users (farmers, foresters, advisers and others) (EIP-AGRI, 2020d, 2020e). Under Horizon 2020, 34 Thematic Networks were financed, for which a total of 68 million Euros were allocated, most of them focused on agricultural techniques. 1.2. INNOVATIVE SOIL MANAGEMENT PRACTICES Agroforestry practices and circular economy, including the use of sewage sludge, have become one of the most relevant innovations promoted by the European Union in the last years due to the linkage of agroforestry and the inputs of organic wastes to the sustainable land management, its carbon sequestration capacity while mitigating climate change and adapting agricultural products to the variable weather conditions that the understory (crops, grasslands) have to face (Augère-Granier, 2020; Mosquera-Losada et al., 2017b). Moreover, agroforestry is a complex land use management that needs research and innovation development associated with both their woody and agricultural component (Mosquera-Losada et al., 2018) in addition to the use of sewage sludge or biosolids, that has to be carefully evaluated due to the harmful impact heavy metals can cause (Mosquera-Losada et al., 2017a). 1.2.1. Agroforestry practices Agroforestry is, according to Mosquera-Losada et al. (2016) and the EIP-AGRI focus group (EIP-AGRI, 2016a), “the integration of woody vegetation in at least two vertical layers on land, with the bottom layer providing an agricultural product such crops or forage/pasture which may be consumed by animals. The distribution of the woody vegetation can be uneven or evenly distributed and the woody component can deliver an agronomic product (fruit, forage) and some other ecosystem services”. It is a type of climate smart agriculture and the European Union encourages its employment by subsidizing 80% of the amount of eligible investments for its implementation through the Regulation (EU) No 1305/2013 of the European Parliament and of the Council of 17 December 2013, on support for rural development by the European Agricultural Fund for Rural Development (EAFRD) and repealing Council Regulation (EC) No 1698/2005 (European Union, 2013a). Likewise, FAO also encourages its use since, when properly designed and implemented, agroforestry combines best silvicultural and agricultural practices, resulting in a more sustainable use of the territory (FAO, 2013) increasing biodiversity and ecosystem service provision when compared to traditional agriculture and forestry (Torralba et al., 2016). According to Mosquera-Losada et al. (2017), agroforestry systems meet at least 9 of the 17 United Nations (UN) Sustainable Development Goals (SDGs) to a greater or lesser extent: - 2. Zero hunger - 3. Good health and well-being - 6. Clean water and sanitation - 7. Affordable and clean energy - 8. Decent work and economic growth - 11. Sustainable cities and communities - 12. Responsible consumption and production - 13. Climate action - 15. Life on land DARÍO ARIAS MARTÍNEZ 4 The most common agroforestry practices in Europe are silvopasture, homegardens or kitchen gardens, riparian buffer strips, silvoarable and forest farming (Mosquera-Losada et al., 2016). Silvopastoral systems, defined as any agroforestry practice that includes trees with the production of forage and animals (FAO, 2013; Mosquera-Losada et al., 2009), are the type of agroforestry practice occupying the largest area in the European Union (17.78 million hectares, representing 4.1% of European territory) (Mosquera-Losada et al., 2016). 1.2.2. Soil carbon sequestration in silvopastoral systems There is an increasing knowledge of the dependence of food security, sustainability, climate change, greenhouse gas emissions, the provision of ecosystem services and carbon sequestration on soil. Moreover, the soil plays a key role in mitigating climate change, since it constitutes the largest terrestrial deposit of carbon, containing more carbon than all aboveground biomass and, therefore, regulating emissions of carbon dioxide and other greenhouse gases (European Commission, 2012a; FAO, 2015; Paustian et al., 2016), as soils together with the water bodies store a quarter of the man-made CO2 emissions (European Commission, 2015a). It is currently estimated that the Earth's surface layer, ranging from the surface to a depth of 1 m, stores approximately 1500 Pg of C and around 2400 Pg of C to a depth of 2 m (Batjes, 1996; Paustian et al., 2016; Rumpel et al., 2020). Therefore, variations in this deposit could have global consequences since the Soil Organic Carbon (SOC) is affected by climate change and at the same time variations in the SOC have an impact on climate change (European Environment Agency, 2017). Thus, the reduction of 1 Pg of carbon in the soil is equivalent to an increase of 0.47 ppm of CO2 in the atmosphere (Lal, 2013), acquiring this way the soil the role of environmental health indicator (Nair et al., 2010). The soil carbon sequestration rate depends on numerous factors, such as the texture of the soil, the characteristics of the edaphic profile, the climate, the plant species and their management, varying in agricultural soils from 0 to 150 kg C per ha and year in warm and dry regions and from 100 to 1000 kg C per ha and year in humid and cool climates (Lal, 2005, 2004). The variation in the carbon stored in the soil also depends on the use of the soil, thus variations in the management of the soil or in its coverage will lead to differences both at above and underground levels. Several studies have compared different land uses in the carbon storage capacity of the soil (Haile et al., 2010, 2008; Howlett et al., 2011b; Rodríguez-Murillo, 2001) concluding that, although with different results, land uses that include some type of permanent vegetation, as happens in agroforestry systems, accumulate more carbon in the underground layer under the same environmental conditions, possibly due to the greater contribution of organic matter and the subsequent root decomposition. Among all agroforestry practices types, silvopastoral systems store more carbon in the soil than the others and this is retained for a longer time (Baah-Acheamfour et al., 2014; Feliciano et al., 2018) although it depends on variables such as soil texture, climate and existing vegetation. 1.2.3. Circular economy and the use of sewage sludge waste To reduce waste environmental impact and get advantage from a residue that may increase carbon sequestration in the soil it is important to understand how waste inputs can increase soil organic matter while causing minimal disturbances in the soil. According to Lal (2004), there are several recommended management practices that lead to carbon sequestration in the soil, such as mulching, conservation tillage, agroforestry and crop INTRODUCTION 5 diversification, cover crops and integrated management of nutrients, including the use of manure, compost, biosolids or sewage sludge , improved grazing and forest management. Biosolids can come from different sources. One of them is the sewage sludge, defined by European (EU, 1986) and Spanish legislation (BOE, 1990) as “residual sludge, whether treated or untreated, from urban waste water treatment plants”. This type of waste becomes especially relevant since 1991, when the European Union, in its Council Directive of 21 May 1991 concerning urban waste water treatment (91/271/CEE), establishes the deadline of December 31 2005 for all urban agglomerations to have collecting systems for urban wastewater to progressively suppress the evacuation of sludge to surface waters to guarantee environmental protection and promote the recycling of sludge produced this way (EU, 1991). Up to 138 million tons of biological wastes with high added value are produced annually in the European Union to be used as raw material for other production processes and of which up to 40% are deposited in landfills (European Commission, 2018a). Thus, the use of biosolids from sewage treatment plants constitutes at the same time a mechanism for reusing a resource that would otherwise be stored in landfills or incinerated, with the consequent detrimental effect on the environment. Moreover, the use of sewage sludge can be considered as a very useful resource for soil and crops due to its high content of organic matter and fertilizer elements the biosolid has. One of the ways in which these residues can be reused is through their application as fertilizers in agriculture, provided that three conditions are met: i) that they are stabilized to reduce their fermentation power and the health problems of their use; ii) that the sludge and soils to be applied do not exceed the concentrations of heavy metals established by legislation and iii) that the quantities applied per hectare and year do not exceed the established limit values for incorporation of heavy metals (BOE, 1990; EU, 1986). The use of the sewage as fertilizer has given rise to several debates, dating back to 1986 with the last regulation approved at EU level. A draft regulation regarding sewage sludge use in agriculture was published in 2000, however it was not approved by the member states due to the high heavy metal use restrictions. Moreover, the regulation of biofertilizers launched by the European Commission in 2019 (European Union, 2019) does not include specifically the sewage sludge, due to the lack of consensus of the EU Member States. This is indicative of the need of innovations development based on research but also in local knowledge. This PhD develops an innovation largely needed in Europe due to the association of the production of sewage sludge to the waste produced in the municipalities larger than 2.000 inhabitants. However, in the USA there is a consolidated legal regulation that not only allows the use of sewage sludge as fertilizer but explains how it should be used taking into account the levels of heavy metals as well as the content of nitrogen and the rate of mineralization associated with the different stabilization processes of the sewage sludge: compost, anaerobic and aerobic. However, one of the main concerns on the use of sewage sludge is the large amount of humidity it has, which has been solved in some areas by the dehydration through thermal drying processes. The use of sewage sludge as a fertilizer in agriculture constitutes a viable alternative to the use of mineral fertilizers (Mosquera-Losada et al., 2019), whose use increased 2.9 % in 2020 compared with 2019 and 8.3 % compared with the level in 2010 in the EU (Eurostat, 2022a), that causes large emissions of greenhouse gases associated with the climate change. The use of sewage sludge also matches with the adoption of a circular economy, in which the value of products, materials and resources are kept in the economy for as long as possible and in which the generation of waste is minimized (European Commission, 2015b) and with the bioeconomy by reducing the environmental footprint. Furthermore, the use of sewage sludge DARÍO ARIAS MARTÍNEZ 6 as fertilizer meet targets 12.4 and 12.5 of the Sustainable Development Goals related to waste management and generation (United Nations, 2017). Within the European Union, the circular economy is one of the main elements of the European Green Deal to achieve a sustainable economy and to become the first climateneutral continent (European Commission, 2019a). To this end, an Action Plan for the circular economy was signed in March 2020, which, among other measures, aims to ensure that less waste is produced and transformed into high-quality secondary resources (European Commission, 2020b). Likewise, the EIP-AGRI also collaborates with the promotion of the circular economy by sharing innovative technologies and practices for its implementation by farmers (EIP-AGRI, 2020f), thus favouring research and innovation. 2. OBJECTIVES The overall objective of this doctoral thesis is to evaluate the agricultural and forestry innovations across the EU by analysing the EU Thematic Networks and to assess the effect of the innovative use of sewage sludge in walnut silvopastoral systems. These two general objectives will be treated in detail in the three following chapters, dedicating two of them to innovation issues and the last one to the innovative use of sewage sludge as part of the EU circular economy, with these particular aims: 1. To analyse the scope of Thematic Networks, in order to elucidate the main topics and targets in terms of land use and location, and the types of exploitation, workers and management involved, to know what are the preferred topics by researchers and those less analysed, and therefore with a higher need for innovation research and implementation. 2. To evaluate the EU networking as a result of the participation of coordinators or partners from different countries in EU funded Thematic Networks, the materials produced and their sources of knowledge, and the way in which TNs established synergies with other initiatives to know the origin, foster future networking and increase the availability of knowledge. 3. To develop a sewage sludge use innovation by investigating the effect of the use of different types of sewage sludge (anaerobic, composted, and pelletised) on chemical (pH) and physical properties of the soil as well as on total and fractionated soil carbon storage, tree growth and pasture production when compared with control treatments (no fertilisation and mineral fertilisation) in a silvopastoral system established under Juglans regia L. in order to evaluate its real storage capacity in the soil, providing a circular economy approach by innovatively revaluing urban waste. 3. THE EIP-AGRI THEMATIC NETWORKS: FOSTERING INNOVATION IN EUROPE 3.1. ABSTRACT The Agricultural European Innovation Partnership (EIP-AGRI), currently named CAP Network, was developed in the middle of the last decade to foster the promotion and adoption of innovations in agriculture and forestry. EU realized that the high level agricultural research results were actually not implemented at field level, which means a deep divide between research and practice. The development of multi-actor approach projects, in which different actors share, collaborate and co-create to find innovative solutions and best practices, contribute to the development and future implementation and adoption of innovations due to the integration of relevant actors. More specifically, European Horizon 2020 funded Thematic Networks (TNs) gather existing knowledge and best practices on agriculture and forestry to make them available in easily and understandable formats for end-users, including advisors, farmers and foresters. The analysis of 28 Horizon 2020 TNs in this study aims at understanding how is the innovation deployment associated with the main EU land uses, implementation areas, farming types, and specific management tackled by the EU Thematic Networks to further propose future topics that are receiving little attention. The analysis was conducted after interviewing and surveying TN coordinators and partners, with previously validated questions. Major findings indicate that TNs mainly tackle arable lands, include all farming types and most of them have a focus on rural areas, addressing the bioeconomy topic by linking rural, peri-urban and urban areas. The analysis of multi-actor approach projects, as TNs, can help to provide insights on how to expand agricultural innovation, identifying areas of study and practices less represented and promoting them in future TNs. 3.2. INTRODUCTION Innovation development in agriculture is one of the most useful ways to move forward in the implementation of the last research findings at real field scale and therefore at farm level (Feo et al., 2022b). Agriculture and forestry research has made important advances to foster sustainability in the last decades. However, most farmers are still not using updated methodologies in the field, relying on the intensive farming practices promoted in the European Union (EU) during the last century as a result of the green revolution. These practices are unsustainable due to the lack of proper advice and the required infrastructure to modernize farming systems (Sial et al., 2021). FAO (2020) describes innovation as a process whereby individuals or organizations bring new or existing products, processes or ways of organization into use for the first time in a specific context, to increase effectiveness, competitiveness, and resilience to overcome a specific challenge. Agricultural innovation is defined by the Global Forum for Rural Advisory Services as a network of organizations, enterprises, and individuals focused on bringing new products, new processes, and new forms of organizations into social and economic use, together with the institutions and policies that affect their innovative behavior and performance (Hall et al., 2006). This interactive system is made of individuals and organizations that demand and supply knowledge, as well as the policies and mechanisms that affect the way different agents interact to share, access, and exchange knowledge (Sulaiman, 2015). Moreover, FAO (2020) DARÍO ARIAS MARTÍNEZ 16 exclusively with part-time farmers. Regarding gender, 45.5% of the TNs dealt with both men and women, and 54.5% reported that they specifically addressed women as a target group (Fig. 6). Fig. 6. Percentage of TNs focusing on full time/part time (above) and gender (below). 3.4.4. Farm management Most farming systems tackled by TNs were linked to conventional (72.7 %), followed by organic farming (63.3 %), while less relevance was given to other types of farming systems, such as precision, mixed, conservation and low-input farming systems (Fig. 7). Most TNs were focused on one or two topics (mainly conventional and organic farming) followed by a small proportion that dealt simultaneously with three or more types of farming systems. 30.0% 0.0% 70.0% 70.0% 0% 20% 40% 60% 80% 100% Full time Part time Thematic Network (%) Working time Both Alone 54.5% 0.0% 45.5% 45.5% 0% 20% 40% 60% 80% 100% Women Men Thematic Network (%) Gender involvement Both Alone THE EIP-AGRI THEMATIC NETWORKS 17 Fig. 7. Types of farming systems (above) and number of farming system types simultaneously tackled by the different TNs (Precision farming, Mixed farming, Conservation agri, Low input, Organic, Conventional) (below). 3.5. DISCUSSION All types of agricultural land uses declared by the EC as eligible to CAP direct payments (European Parliament and European Council, 2021) were already included in the development of TN innovation approved between 2015 and 2018. However, TNs focused more on intensively managed farmlands (arable and permanent crops) than on those with a lower degree of intensification (permanent grasslands). In this context, it is important to be aware that grassland occupies more than 50 % of the EU’s utilized agricultural area land and it is the land type with the highest proportion of biodiversity in Europe (Osoro et al., 2016). Similarly, the focus groups organized by the EIP-AGRI (2020b) had less representation of grazing systems and therefore of permanent grasslands. Both, arable lands (Fonderflick et al., 2020) and permanent crops (Van Der Meer et al., 2020) are those types of lands receiving the highest proportion of herbicides, pesticides and fertilizers across Europe and therefore with the greatest need to develop innovations to increase the sustainability of agriculture in Europe. Permanent grasslands, which are also eligible for direct payments and can be linked to animal production, have received less attention maybe due to the declining use of grazing as part of livestock farming systems (Schils et al., 2019), making livestock production usually linked to indoor systems and therefore being less sustainable. Moreover, most TNs focused on a single type of land use (either arable crops, permanent grasslands, forestry or permanent crops), which limits the optimization of the efficiency of the mixed farming systems at the farm and landscape scale (EIP-AGRI, 2017). Agroforestry and forestry -which are activities mostly financed by the Pillar II of the CAP and therefore receive payments based on the fulfillment of certain types of farming practices, but not on direct payments-, were less relevant for the 72.7% 63.6% 36.4% 31.8% 31.8% 31.8% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% Conventional Organic Low input Conservation Agri Mixed Farming Precision Farming Thematic Network (%) Farming system types 31.8% 31.8% 4.5% 13.6% 4.5% 13.6% 0% 10% 20% 30% 40% 1 2 3 4 5 6 Thematic Network (%) Number of farming systems DARÍO ARIAS MARTÍNEZ 18 TNs. The latter are mainly related to the farming techniques currently used by intensive foodbased systems and therefore those types of land use on European farms that need more innovation to become more sustainable and, at the same time, ensure farmer’s income. Therefore, it can be concluded that TNs focused on those highly demanding issues that lead the transition towards land use sustainability. On the other hand, most of the topics addressed by the TNs were linked to lowlands and highlands, despite the fact that mountain areas represent 36 % of the EU area (Drexler et al., 2016). Moreover, it has been noticed that less-favored and marginal lands, as highlands, need more innovation to increase their potential to supply food for the growing European population. All TNs focused on rural areas due to their focus on EIP-AGRI sectors, but more than 25 % of TNs linked their activity also to urban and periurban areas. The connection between rural areas with periurban areas ensures the sustainability and circularity of the European bioeconomy, which will promote the modernization of the primary production systems, environment protection and enhance biodiversity (European Commission, 2018b) through the development of short value chains. Furthermore, in 2012, 51.3 % of the EU’s land area was classified as predominantly rural, giving home to 22.2 % of the European population and providing food, raw materials, environmental goods and jobs (Eurostat, 2017a). These rural areas should support short value chains in Europe to increase sustainable farming systems thanks to the higher share of added value received by farmers, strengthening local economies, reducing the carbon footprint when the food is distributed while sustaining the viability of small companies (Markuszewska et al., 2012). This became particularly important from the rise of the COVID-19 pandemic. This study also found that EU-funded TNs considered both small and large farms that represent 70 % and 15 % of European farms, respectively (Eurostat, 2016), and also those related to both transitional farming systems (such as organic farming) with a share of 7.5 % of European farms (European Commission, 2019b) and conventional farming systems. TNs also took into account the management unit, as they targeted family farms, cooperatives or collective farms. In general, farm size type and management were well addressed by most TNs, which is a key point for European agriculture to move towards more sustainable farming systems. The organizational basis of the farms in Europe was also adequately addressed by most TNs, as they took into account all these types of farm organization, including family farming, which represents 95.2 % of farms in the EU (Eurostat, 2020a) and cooperative farming, which currently involves around 21,769 cooperatives with over 6 million of members (COPA-COGECA, 2014), in addition to collective farming. Similarly, TNs adequately considered work-time and gender, as they all targeted full-time farmers, who are key to family farms (Davidova and Thomson, 2014) and women specifically, who currently manage 30 % of European farms (Franić and Kovačićek, 2019). On the opposite side, in this study we found several knowledge gaps that were not addressed by the TNs. These included sustainable land use practices that combine perennial woody plants (trees and/or shrubs) with agricultural production -i.e. agroforestry-, less favored areas (mountain areas that host most of Europe‘s biodiversity), and value chain and bioeconomy development as a way to integrate the food system aligned with the land management and the agricultural and urban areas connections. Agroforestry practices were under-evaluated in most TNs, although they can be implemented in any of the land cover types (permanent grassland, permanent crops, arable crops and forestry). Note that agroforestry practices are recognized by the Intergovernmental Panel on Climate Change (IPCC, 2018) as one of the most important tools to mitigate and adapt farming systems to THE EIP-AGRI THEMATIC NETWORKS 19 climate change. Moreover, fostering land use innovation systems such as agroecology and/or agroforestry should be linked to an adequate development of supply chains as a way to ensure income and recognize the initial effort needed to carry out sustainable practices (MosqueraLosada and Prabhu, 2019), being a clear gap found in our analysis. Finally, the sustainable farm transition should be understood as a whole, considering the adequate development of business models and business plans that foster the sale of food, and sustainably produced raw material. It should be also based on the transformation of products to increase added value following the principles of bioeconomy and circular economy. Attending to the European Commission (2018), the bioeconomy should be based on three key aspects such as the development of new technologies and processes for the bioeconomy, markets and competitiveness in the bioeconomy sectors in addition to driving policy makers and stakeholders to collaborate more closely; while the circular economy is based on principles linked to waste and pollution design, keeping products and materials in use and regenerating natural systems. Unfortunately, none of the TNs specifically dealt with these issues, but some of them addressed certain aspects of bioeconomy and circular economy in some of the innovations developed. 3.5.1. Policy implications There is a clear link between the TNs funded under the Horizon 2020 programme and the communications released by the European Union related to climate, nature, and agriculture and forestry. All TNs match with the commitment of the European Commission of tackling climate and environmental-related challenges and the priority set by the European Green Deal of putting people first, paying attention to the regions, industries and workers who will face the greatest challenges, by promoting active public participation (European Commission, 2019a). The research and innovation made by TNs translate scientific findings into viable solutions and actions that can help mitigate the effects of climate change, connecting people from diverse backgrounds, and therefore playing an essential role in developing and promoting the use of the solutions needed to reach the EU´s climate ambition set in the European Climate Pact (European Commission, 2020d). The results obtained have revealed the areas where sustainable practices are more necessary, either by their low representation in agricultural systems or by their need of innovation due to the impact these activities pose. Farmers in these areas need to change the way they produce to make a better use of the solutions found to adapt their farming systems to climate change, increase climate resilience, reduce and optimize the use of inputs, while avoiding the loss of biodiversity, which subsequently results in reduced crop yields (European Commission, 2021b, 2020a). This transition towards a sustainable system will change the economic fabric of many EU regions and their patterns of interactions (European Commission, 2020a), resulting in the creation of new or specialized jobs. TNs also match with six of the ten key policy objectives of the CAP 2023-27, which seeks to ensure a sustainable future for European farmers, provide more targeted support to smaller farms, and allow greater flexibility for EU countries to adapt measures to local conditions (European Commission, 2021c):  to increase competitiveness;  to improve the position of farmers in the food chain;  climate change action;  environmental care;  to preserve landscapes and biodiversity;  fostering knowledge and innovation DARÍO ARIAS MARTÍNEZ 20 The job initiated by the Horizon 2020 has been continued by the Horizon Europe, which has funded initiatives that seek to combine societal pull and technology push to set relevant solutions that implement the Green Deal at the same time they engage local communities to set a more sustainable future (European Commission, 2019a). 3.6. CONCLUSIONS TNs, considered as crucial for fostering agricultural innovation in Europe, mainly targeted the farms that needed more innovation (arable lands) and all kinds of relevant farm typologies (small/large, family farms/cooperatives, conventional/organic). However, more attention should be paid to sustainable practices linked to value chains/bioeconomy/circular economy and also different types of land use such as agroforestry and those related to less favored areas or marginal lands. 4. THEMATIC NETWORKS DATA ORIGIN AND THEIR SYNERGIES WITH OTHER EIP-AGRI INITIATIVES 4.1. ABSTRACT The management of land use within the framework of the Common Agricultural Policy (CAP) is crucial for sustainable agricultural practices and rural development in the European Union. The CAP serves as a foundational policy tool for regulating land use, aiming to support modern, market-oriented farming and foster innovation in the agricultural sector. Innovation and knowledge exchange are vital components for optimizing land use practices, as they facilitate the dissemination of best practices, sustainable techniques, and cutting-edge research findings. Collaboration among stakeholders, including policymakers, researchers, and farmers, is essential to ensure the effective implementation of land use policies and to drive continuous improvements in agricultural practices. Robust research initiatives underpin these efforts, providing the evidence base for informed decision-making and the development of sustainable land use strategies within the CAP framework by producing updated innovation documents and by keeping large innovation networks among actors in order to increase innovation spread and reach a higher number of end-users, especially in less represented countries or areas. 4.2. INTRODUCTION Innovation in all economic sectors constitutes a source of knowledge for the development and improvement of new technologies and methodologies, representing one of the determining factors of growth in the long term (Peñate-Valentín, 2020). In most cases it comes from research, which is normally supported by public funding, that allows transforming ideas into knowledge suitable to emerge as technologies (Tait, 2001) applicable in many different fields. However, the transition from the initial idea or necessity to the adoption of effective technologies has to be supported by policies and institutions, spreading innovations and know-how in order to underpin growth and decrease productivity differences among the regions (Čechura et al., 2014). From the environmental point of view, research and innovation in agricultural and forestry sectors is essential to prevent biodiversity loss and the effects of climate change, contributing to the evolution of farming systems tailored to specific needs (Tait, 2001). This is especially relevant for primary producers, who have a particular need for objective, tailored advisory services on sustainable management choices (European Commission, 2020a) in order to adapt their production systems to be more sustainable in the face of changing climate and soil conditions. Policies should also be based on innovation, paying major attention to learning processes and facilitating the imitation of technologies (Baráth and Fertő, 2017) and based on an informed society which constantly integrates scientific advances from various research disciplines (Tait, 2001). However, as stated by Fieldsend et al. (2020), innovation rests not only on discovery but also on cooperation and interactive learning, entailing the optimization of the sharing and exploitation of the diverse resources of a multi-actor partnership. This process involves universities and research centers that generate the knowledge base for technological innovations that support truly sustainable farming systems (Doornbos, 2001), and policy makers that translate these innovations into regulations that farmers can easily adopt by DARÍO ARIAS MARTÍNEZ 22 increasing farmers’ awareness of sustainable practices (Dessart et al., 2019). Therefore, farmers need to have access to abundant and neutral information disseminated by reliable data and technical guidance adapted to local conditions (Shinohara, 2001) to comply with environmental and social requirements supported by the Common Agricultural Policy (CAP). The current 2023-2027 CAP relies on Member States' own strategic plans framed by the 10 key CAP objectives in order to help each Member State better adjust policy interventions to their local conditions and needs (European Commission, 2021c), while maximizing the ecosystem services provision from agriculture. To support the implementation and evaluation of the CAP Strategic Plans and boost innovation in the sector, the European Commission launched the European CAP Network that aims to optimize the flow of information about agriculture and rural policy within the EU and to support the transition to a sustainable, resilient, and modern European agricultural sector (European Commission, 2022a). It brings together stakeholders from the European Network for Rural Development and EIP-AGRI to drive and steer all aspects of the implementation of the EU Common Agricultural Policy (European Commission, 2023c). Several EU regulations encourage the adoption of sustainable agricultural practices as the EU Biodiversity Strategy for 2030 (European Commission, 2021b) and the Farm to Fork Strategy (European Commission, 2020a), that promotes an effective Agricultural Knowledge and Innovation Systems (AKIS) that involves all food chain actors. In this regard, the European Innovation Partnership for Agricultural Productivity and Sustainability (EIP-AGRI) was set with the aim of fostering innovation in agriculture, forestry and rural development and to create synergies between different policy programmes both at the EU and Member State level (Fieldsend et al., 2021). The EIP-AGRI and Horizon 2020 have collaborated to fund projects aimed at boosting agricultural innovation and addressing challenges faced by farmers and foresters through the CAP. Horizon 2020, with a budget of around 3.7 billion Euros for 2014-2020, focused on creating solutions for current issues in agriculture, forestry, marine, maritime, and inland water research, and the bioeconomy. The EIP-AGRI (EIP-AGRI, 2019) supports different types of projects in which researchers and stakeholders work together to develop practical solutions, actively supported by the Horizon Europe, as multi-actor projects (CSA, RIAs and IAs), and by the CAP,which funds multi-actor projects associated with the Operational Groups. Among all projects financed by Horizon 2020, Thematic Networks (TNs) are a particular type of multi-actor projects which collect existing knowledge and best practices on a given theme to make it available in easily understandable formats for end-users such as farmers, foresters, advisors and others (EIP-AGRI, 2020e). Operational Groups (OG), which were formerly funded by Rural Development Programmes (RDP) and currently through the national CAP Strategic Plans developed in each Member State, are intended to bring together multiple actors such as farmers, researchers, advisors, businesses, environmental groups, consumer interest groups or other NGOs to advance innovation in the agricultural and forestry sectors (EIP-AGRI, 2020j) by tackling a specific challenge or opportunity on a local, regional or national scale (EIP-AGRI, 2017b). These multi-actor projects are required to produce short Practice Abstracts (PA) to outline their plans and main findings (EIP-AGRI, 2019). PAs are defined by the European Commission as short, informative recommendations and solutions (EIP-AGRI, 2016b) and are created following a common format to translate the knowledge generated by multi-actor projects, Thematic Networks, and Operational Groups into easily understandable material for end-users. PAs increase the dissemination of the projects and the knowledge exchange THEMATIC NETWORKS DATA ORIGIN AND SYNERGIES 23 throughout the project’s life-cycle, providing usable results that facilitates knowledge uptake by farmers and producers (EIP-AGRI, 2017b). Organizations and individuals from and across the EU and associated countries can participate in EIP-AGRI and Horizon 2020 projects, creating a collaborative ecosystem that enriches knowledge creation in those fields that need solutions or improvements and that are directly applicable by end-users (EIP-AGRI, 2020d). However, participation may be unevenly distributed, with a general trend of correlation between the level of development and the capacity to attract funds and projects (Varela-Vázquez et al., 2019) and the links among initiatives are not clear, needing a development of systematic connections to enhance the synergies within the EIP-AGRI landscape (Mosquera-Losada et al., 2020). Within the Horizon 2020 EURAKNOS2 project, an analysis of the funded TNs was performed in order to evaluate the participation of EU and non-EU countries, their output production, and their ability to establish synergies among them and with other EIP-AGRI initiatives such as Operational Groups (OGs). It also created “the network to connect all thematic networks” to explore the feasibility of creating a modular database of useful findings from various thematic networks to strengthen the EU agricultural knowledge base (EURAKNOS, 2019) by making an evaluation of past and running TNs and other EIP-AGRI highly related activities (linked multi-actor approach H2020 projects and relevant OGs as case studies). The objective of this paper is to evaluate the participation of the different countries in TNs, either as coordinators or as partners, the materials they have produced and their sources of knowledge, and the way in which they established synergies with other initiatives to know the origin, foster future relationships and increase the availability of knowledge across the EU. 4.3. MATERIAL AND METHODS Within the EURAKNOS project, which intended to foster the best practices exchange among farmers, researchers and advisors from different sectors and member states, four different tasks were carried out between January 2019 and March 2021: 1) An assay using Geographical Information System (GIS) tools to illustrate graphically the countries taking part in TNs; 2) A database compilation with all the materials produced by TNs and OGs; 3) An oral questionnaire answered by TN partners, and 4) A written survey sent to TN partners. All TNs funded from 2015 (34) were considered for study between January and March 2019, but as six TNs were at an early stage of development and did not have a dedicated webpage or it had not available information stored, only 28 TNs were finally analyzed (Table 3). The degree of completion of each TN was calculated at the moment this study was performed (January 2019) by considering the months elapsed with respect to the total duration of each project, expressed as a percentage. 2 Project funded from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 817863. https://euraknos.eu/ DARÍO ARIAS MARTÍNEZ 24 Table 3. Thematic Networks considered in this study and their degree of completion represented by colors and percentages. H2020 THEMATIC NETWORK Degree of completion H2020 THEMATIC NETWORK Degree of completion H2020 THEMATIC NETWORK Degree of completion AGRI-SPIN 100 % 4D4F 97 % NEWBIE 39 % SMART-AKIS 100 % SheepNet 78 % PANACEA 39 % AGRIFORVALOR 100 % SKIN 78 % OKNeT Ecofeed 39 % OK-Net-Arable 100 % CERERE 75 % INNOSETA 25 % FERTINNOWA 100 % EU Pig 73 % best4soil 14 % WINETWORK 100 % AFINET 72 % Nutriman 14 % HENNOVATION 100 % Inno4Grass 72 % Suwanu 8 % EuroDairy 100 % INCREDIBLE 48 % legumes translated 8 % HNV-LINK 97 % ENABLING 39 % Disarm 6 % EUFRUIT 97 % TNs were classified according to the land use types set by the European Commission and that are eligible to receive CAP direct payments (European Union, 2013b), i.e. arable crops, permanent crops, permanent grassland as well as forestry, although some of them were not included in any of these categories and some others were included in more than one type. Once TNs were selected, and with the purpose of illustrating graphically the participation of the countries involved in TNs, six maps were elaborated, representing the number of projects coordinated by country, the number of associates per country participating in projects and one map per each of the land use categories considered depicting the number of institutions taking part in projects related to them by country. Maps were created using the QGIS software, version 3.26.3 (QGIS.org, 2023), differentiating between EU-283 countries and non-EU countries. A database with all the outputs produced by TNs and OGs and publicly available on their websites and CORDIS (Community Research and Development Information Service) was 3 When this study was performed United Kingdom was an EU Member State. THEMATIC NETWORKS DATA ORIGIN AND SYNERGIES 25 compiled by the end of July 2019. Each material was identified with the TN or OG of origin, title, internet link to the document, content (differentiating between Technology if ICT tools were involved and Best practice if practices were involved) and format of the document, following the structure of the Table 4, containing the most relevant information of each document generated. Each data was categorized under the arable crop, permanent crop, and permanent grassland sectors based on the CAP eligibility land use (Regulation 1307/2013), and forestry. Some of them could be allocated to more than one specific category and others were not allocated to any specific category. Each document or material description included the most relevant keywords that gave a significant meaning by a single word or short phrase. The final database comprised 5064 rows plus 690 additional practice abstract links, however only 3776 files had a valid internet link and were further analyzed. Table 4. Material database structure and options. TN name Title of material Internet link Content Format EIP-AGRI sector Keywords - Technology - Best practice - Text - Excel - Video - Infographics - Arable crop - Permanent crop - Permanent grassland - Forestry The methodology for the analysis of the information gathered in this database was carried out by counting the keywords in each related EIP-AGRI sector, which allowed the creation of word clouds displaying the most frequently used terms in different sizes and colors based on the frequencies, providing a graphical representation that allowed to form a quick and intuitive sense of the documents produced in an easy way, sharing high-level data without information overload (DePaolo and Wilkinson, 2014). Only English words or phrases were taken into consideration in order to homogenize the results. Additionally, an oral survey and a written online questionnaire were created to gather supplementary information following the Delphi methodology in order to get the consensual opinion of a group of experts by means of several questionnaires validated in three steps and alternated with opinion feedback (Dalkey and Helmer, 1963). The first step was performing a draft questionnaire which was discussed and circulated among EURAKNOS project partners. Then the list of questions was validated by TN coordinators participating in the project consortium (SMART AKIS, Hennovation, OK-net Arable, Inno4Grass, and AFINET) and redrafted afterwards, differentiating between the questions kept for the oral interviews and those questions to be included in the written questionnaire. Oral interviews were performed either personally or virtually by different EURAKNOS partners. Questions (Table 5) were related to data production issues and the connections with other EIP-AGRI initiatives. The answers were rated according to a Likert scale (Strongly agree, Agree, Neither agree nor disagree, Disagree, Strongly disagree, and Not able to answer). Members from all the TNs investigated were contacted, however only 25 TNs´ partners were finally interviewed. DARÍO ARIAS MARTÍNEZ 32 The percentage of all format types of the outputs produced by the TNs can be seen in Fig. 15. More than 50 % of the TNs produced eight types of outputs with a range between two and fourteen. Practice abstracts, factsheets, press releases, research articles (scientific papers), reviews and technical articles were the most produced outputs by the different TNs as over 65 % of the TNs included them as part of their outputs. Most of the TNs produced outputs were written documents even though over 40 % produced audiovisual materials such as videos and only 20 % of them delivered podcasts. Other types of materials included policy briefs, educational materials, webinars and social media publications. Fig. 15. Type of formats of the materials produced by the Thematic Networks. Regarding the results obtained from the questionnaires, the first question of the oral interview was related to the time and effort each TN dedicated to produce different outputs to communicate and disseminate their work. From this question, it was observed that 84 % of the interviewed TNs dedicate a higher effort to produce best practice guides, followed closely by practice abstracts and videos (80 %), and factsheets (76 %). Less than 50 % of the TNs work in the production of other communication and dissemination materials such as research articles, pictures, booklets, press releases, handbooks, podcasts and other type of materials as policy briefs, educational materials and webinars. Each TN responsible was asked to categorize the data they produced according to Farm description or Practice depending on their main purpose. Out of the TNs interviewed, 88 % classified their output as practice, 64 % as farm description and 56 % as both farm description and practice. TN outputs were created based mainly on previous existing documents from researchers and advisors, and also complemented with their expertise in 23 and 21 of the TNs interviewed, respectively. Farmer´s experience was also taken into consideration in 19 TNs, as well as other sources of information such as industries, stakeholders, policy makers and technology developers in 12 TNs. Literature review, followed by interactive activities such as workshops and interviews were key to develop the information needed to fulfill the innovations described in those TNs implemented by the EIP-AGRI during the four years of the H2020 call included in this study. Other activities that include innovation partnership groups, technology reviews and case studies were also taken into account. Benchmarking to get ideas applicable to a certain topic was less representative (Fig. 16). THEMATIC NETWORKS DATA ORIGIN AND SYNERGIES 33 Fig. 16. Activities performed to gather information for the Thematic Networks. Table 6 shows the validated multi-actor definition of the main outputs produced by TNs. Definitions were proposed following the literature review of the different types of documents found in the TN web pages along with their target groups, which were validated in the Budapest workshop. DARÍO ARIAS MARTÍNEZ 34 Table 6. Definitions of the main outputs produced by the Thematic Networks (TNs) and main target groups. Output Definition Communication / Dissemination Main Target group(s) Press release Official statement delivered to members of the news media for the purpose of providing information, an official statement or making an announcement. To maximize the impact it could be linked to the provision of a solution of a huge society problem. Communication General Public Leaflet A type of small magazine that contains pictures and information about the project. Communication General Public Podcast Digital audio content distributed over the internet. Communication General Public Infographic A representation of information in a graphic format designed to make the data easily understandable at a glance. Communication General Public Newsletter A bulletin issued periodically to the members of the project. Communication General Public Practice abstract A short document that highlights a practice and useful innovation. Dissemination Farmers and researchers Factsheet One single printed sheet with a concise presentation of information in a format which emphasizes key points concisely, usually using tables, bullet points, and/or headings, and printed on a single printed page. They are sometimes a summary of a longer document. Dissemination Farmers and researchers Research paper, Review Paper published in scientific journals indexed in the WoS or any other scientific database as a direct result (Research papers) or as a compilation of results from other papers. Dissemination Researchers Report A document coming from the project that highlights the most important results from a specific project. Dissemination Researchers Technical article A document that describes the nature, state of the art, progress, or results of a technical process. Therefore usually associated to best practices. Dissemination Farmers Guideline A document that describes a process or the know-how of an innovation. Dissemination Farmers Video A film detailing an innovation in images. Dissemination Farmers Handbook A book giving information such as facts on a particular subject or instructions for operating a machine. Dissemination All type of stakeholders THEMATIC NETWORKS DATA ORIGIN AND SYNERGIES 35 Fig. 17 shows the organization schemata of the different documents related to communication and dissemination, differentiating by colors the main target group they are aiming at. Communication materials are created to reach the general public, while dissemination materials are focused on different end-users as researchers, farmers, and policy makers. Fig. 17. Documents produced for Communication and Dissemination within TNs. The different colors of the materials indicate the target group specified in the small box in the left and the materials indicated in bold are those produced in higher amount. 4.4.4. EIP-AGRI synergies When the different TN responsible partners were asked if their TN would be able to make strong connections to other initiatives in the EIP-AGRI landscape, most of them agreed that they were, at the moment of the survey and previously, able to make them. From those TNs answering the question, the percentage of the ability to make connections was in all cases above 50 %, except Multi-actor H2020 Innovation Actions (IA) and for other categories not contemplated in the options given, specifying innovation networks and farmer and stakeholder groups as answers (Fig. 18). Nevertheless, 6.7 % of the TNs answered that they were not able to make a connection to any other initiative due to their initial stage and another 6.7 % would only collaborate with another initiative (data not shown). DARÍO ARIAS MARTÍNEZ 36 Fig. 18. TNs ability to make connections with other EIP-AGRI initiatives. OG: Operational Group, TN: Thematic Network, NRN: National Rural Network, FG: Focus Group, RIA: Research and Innovation Action, CSA: Coordination and Support Action, IA: Innovation Action. When asked how synergies were established, most respondents answered that most of them were based on common consortium partners involved in the TN, which acted as a link to participate in other initiatives. One of the persons surveyed responded that the synergies with many other initiatives were established on events by keeping a former relationship and on the website by attracting the interest of other participants. Among the main reasons for establishing these linkages, many respondents pointed out their use for future projects, and its usefulness to transfer knowledge to end-users and benefit from the exchange of ideas and the cross fertilization. Fig. 19 shows the correlation among the different TN outputs, their classification and sources of information (green boxes) and the EIP-AGRI landscape initiatives (blue boxes). Only positive correlations are shown, with the significance level indicated inside the arrows. Infographics were correlated with National Rural Networks, and Handbooks with National Rural Networks, Multi-Actor H2020 IA, and Multi-Actor H2020 CSA. These types of EIPAGRI initiatives were connected among themselves, and more specifically, Multi-Actor H2020 IA was connected with Multi-Actor H2020 RIA, which was correlated with Farm outputs. Handbooks were also correlated with the total number of group connections. Moreover, Practice Outputs were correlated with the total number of group connections, and Data from Advisors with Operational Groups. THEMATIC NETWORKS DATA ORIGIN AND SYNERGIES 37 Fig. 19. Synergies among outputs and EIP-AGRI initiatives. 4.5. DISCUSSION The different representation of land uses in TNs matches the EU land occupation in 2016, when 62 % of the land used for agricultural production was dedicated to arable land mainly for crops for human and animal consumption productions, 31.2 % was allocated to permanent grasslands to provide fodder and forage for animals and 5.5 % was used for permanent crops such as fruit, olives and grape production (Eurostat, 2020b). The participation in TNs was unevenly distributed across Europe, specially concentrating in western countries, due to the correlation existing between their size and the number of participations and the preference for participants with geographical and cultural proximities (European Commission, 2022b). These countries hold important research infrastructures, large organizations and universities (Wanzenböck and Scherngell, 2013) and are close to the area covered by the ‘blue banana’, with high population density, high added value productions and high traffic (Brunet, 2002). However, the share of EU funding going to eastern countries slowly increased from the previous Framework Programme (FP7) to the Horizon 2020 (European Commission, 2022c) because of a higher openness of EU-15 countries to EU-13 participants4 (European Commission, 2022b). The lower presence of eastern countries is related to the fact that the share of agricultural cover (predominant topics of the TNs) is lower than the forested areas (Eurostat, 2020b). Countries from the central and eastern part of Europe are less represented because of their low research, development and innovation performance (Juhász and Vásáry, 2017) as well as their lower innovation development and transfer, which makes them at the same time more suitable to participate in multi-actor projects in order to adapt these approach schemes and advance in the development of innovation (Mosquera-Losada et al., 2020). Many institutions were involved in more than one TN consortium as, for example, members from Belgium, Ireland, The Netherlands and Denmark, which participated in more than eight TNs. These are normally large academic and research institutions with diverse departments that specialize in different topics and with a long history on project participation that gives them more trust (Fieldsend et al., 2020), normally taking up the responsibility of writing project proposals (Feo et al., 2022b), and placed in countries where the agricultural 4 EU-13 Member States are meant as Bulgaria; Croatia; Cyprus; Czech Republic; Estonia; Hungary; Latvia; Lithuania; Malta; Poland; Romania; Slovakia; and Slovenia, whereas EU-15 countries are the other 15 Member States of the European Union (European Commission, 2022c). DARÍO ARIAS MARTÍNEZ 38 sector is more productive compared to eastern countries (Baráth and Fertő, 2017), where producers have poorer performance and are not able to catch up with the developments of the sector leaders, and therefore lagging behind (Čechura et al., 2014). The lower representation of eastern and southern countries in arable crops is due to a lower extension services development. The most remarkable case is Romania, where this type of agricultural production occupies more than the half of the Utilized Agricultural Area (Eurostat, 2023). Permanent crops had the lowest representation in TNs, although this low representation was more notorious in Greece, which was the third European country with the largest area dedicated to permanent crops in 2021 (Eurostat, 2023), representing a 7.2 % of total EU production in 2019 (Eurostat, 2020b). Permanent grassland was again more represented in western countries, but in this case Austria and Greece are noteworthy because this type of agriculture is present in almost half of their agricultural area as well as Switzerland, where it is estimated to occupy about 72 % of the agricultural area (Eurostat, 2023). EU forests cover 46 % of the Union´s territory (European Parliament, 2020), nevertheless forestry was poorly represented in the TNs, although Finland, with a higher forest relevance, had a higher presence in this type of land use, letting Sweden underrepresented despite the fact that it held the largest EU forest area in 2020 (Eurostat, 2020b). The high presence of water-related keywords for Thematic Networks within arable crops category can be associated to the higher output production of a project specifically dedicated to fertigated crops than other projects under the same category at the date the TN analysis was performed. The common bond for the three elements evaluated under permanent crops was related to viticulture mainly because there was a TN dedicated exclusively to increasing the productivity and sustainability of the wine sector with a high production of materials and that had already ended its lifetime. For permanent grassland, the most relevant words for the three categories considered were related to cow production since the TN dealing with dairy farming had already finished when this study was carried out, despite doubling pig heads the number of bovine heads (142 million and 76 million, respectively) in 2021 (Eurostat, 2022b). Forestry keywords for TNs were mostly focused on non wooded forest products due to the project dedicated to this particular topic, which had a high output production, and the growing understanding of these types of products in the innovation potential for a bio-based economy (Sheppard et al., 2020). However, within each topic, Operational Groups and Practice Abstracts shared keywords concerning the main sector they were related to. Thus, in arable crops the common words were associated to organic production, since OGs aim at promoting agricultural innovation closer to nature and less contaminant. For permanent crops the pattern was wine and fruit production and for permanent grassland the keywords concerned animal farming, mainly cows and pigs. Finally, there was not a clear bond among the forestry categories because there was only one project working on this subject and it covered very different issues. The outputs not related to any of the CAP categories belonged to transversal projects or topics more related with sustainability global concept (Mosquera-Losada et al., 2020), which reflects the importance of innovation to support the competitiveness of farming systems and to improve their environmental performance (Tait, 2001). The high percentage of materials categorized under both practice and farm description was due to the practical sense of TNs and its multi-actor approach, which promotes the relation among researchers and practitioners with ‘complementary forms of knowledge’ (Fieldsend et al., 2020) to build solutions together, and more specifically due to the aim of Thematic Networks to share knowledge and results that are ready to be put into practice. This THEMATIC NETWORKS DATA ORIGIN AND SYNERGIES 39 close relationship was also evidenced by the data source for the creation of the outputs, coming mostly from farmers and researchers, since farmers accrue practical knowledge and researchers bring in the theoretical background (Fieldsend et al., 2020). Both farmers and researchers are, at the same time, the main target groups, since the majority of the materials produced aim at the dissemination of results in order to facilitate the adoption of innovations and were dedicated an according effort, as reflected by the higher production of practice abstracts and factsheets. However, communication materials such as videos, pictures, and press releases were devoted a significant effort in their production due to their ability to reach a wider audience, despite being videos available at a lower rate as also evidenced in the EURAKNOS project (EURAKNOS, 2020). The creation of innovative materials relied mostly on literature review due to the detailed level of research and information they present. However, workshops and interviews were very frequent activities attended to collect information because of the possibilities of co-creation and knowledge exchange among actors they pose, representing the most preferred part of a project by participants (Feo et al., 2022a). Synergies are considered as joint or coordinated efforts to achieve greater impact and efficiency and they can be attained through parallel projects that complement each other (European Commission, 2014), leading to a more likely application of innovations in the field (EIP-AGRI, 2020d). The common keywords between Operational Groups and Practice Abstracts from TNs reflect the openness to involve relevant groups operating in the EIP context (EIP-AGRI, 2020d) and the ability of the Thematic Networks to connect to other initiatives, revealing the suitability of connecting the needs of the European agriculture with the innovation strategies of successful sectors of European industry (Tait, 2001). Moreover, the promotion of practices that foster the dialogue between the consortium and other initiatives supports the co-innovation process through the dissemination and embedding of innovations and the obtainment of feedback (Fieldsend et al., 2020). However, the connections among EIP-AGRI initiatives are unevenly distributed across European countries, locating mainly in western and southern countries (Mosquera-Losada et al., 2020), which host the largest number of participants. Among all the types of initiatives considered in this study, OGs attained the highest ability to make connections with TNs, mostly because they are short projects that promote agricultural innovation, putting into practice innovative solutions by involving multiple actors and are obliged to disseminate their results (EIP-AGRI, 2020h), sharing the knowledge created and fostering the involvement of farmers and their collaboration in the innovation process (Mosquera-Losada et al., 2020). 4.6. CONCLUSIONS Results show an uneven participation among EU countries, mostly due to the differences in the share of land advocated to the different farming types, research development and transfer, and development of innovation and its transfer. The participation of countries with less representation should be encouraged so that they can be adequately advised to adopt last developments and improve their agricultural performance from a sustainability perspective (economic, environmental and social). The best way to increase sustainability in agricultural and forestry systems are the maintenance and increase of innovation documents, such as practice abstracts and factsheets, as well as holding and enlarging innovations networks among actors. Workshops should be particularly promoted in eastern countries in order to foster the involvement of farmers and their inclusion in projects and, thus, facilitating the knowledge exchange and innovation implementation. DARÍO ARIAS MARTÍNEZ 40 More links with OGs and NRNs should be created to promote the relation among researchers and practitioners. Relevant actors, such as policy makers, representatives of the agricultural sector, researchers, stakeholders and farmer associations should be engaged to support the dissemination of innovation measures, facilitating the knowledge transfer, and communication should be well oriented and more effective in order to reach a wider and higher audience. 5. EFFECT OF DIFFERENT FERTILIZATION TREATMENTS ON SOIL CARBON, PASTURE PRODUCTION AND TREE GROWTH IN A WALNUT SILVOPASTORAL SYSTEM 5.1. ABSTRACT The combination of trees and pasture in the same portion of land provides numerous benefits compared to just trees, pastures or crop growing under similar conditions, such as improved biodiversity, soil structure and nutrient excess absorption, among others. It also raises the carbon sequestration potential due to the increased input of organic matter to the soil from the woody layer, especially when canopy closes, providing higher litter input and tree shading that decreases the mineralization rate. The application of organic fertilizers could help to increase tree growth and pasture yields at the same time it constitutes a way of recycling wastes in the case of sewage sludge, providing huge amounts of nutrients and organic matter. Three differently stabilized sludges from water treatment plants were applied before the establishment of a walnut silvopastoral system and compared to mineral fertilization and no fertilization, increasing the initial soil pH, and consequently increasing the organic matter mineralization rate and the carbon concentration and storage in the whole soil as well as the pasture production at the beginning of the experiment. 5.2. INTRODUCTION Agroforestry systems are recognized as an integrated approach for sustainable land use (Lorenz and Lal, 2014) due to the integration of trees or shrubs in croplands and pastures. They are effective C sinks when adequately designed and properly managed since they can contribute to C pools aboveand belowground with a higher potential to sequester C than open pastures or treeless field crops growing under similar ecological conditions (Nair, 2011; Zake et al., 2015). Moreover, trees hold much more carbon per unit of area than other types of vegetation (Houghton, 2007), due to their inputs of organic matter into the soil, both as leaf litter and residues in the surface and as dead roots and exudates deeper in the soil, enhancing soil organic carbon (SOC) stocks (Cardinael et al., 2015a). Since SOC is linked to soil fertility (Lacoste et al., 2016), it can be used as an indicator of soil health (Cong et al., 2017; Ferreiro-Domínguez et al., 2016b). Moreover, an increase in the SOC pool decreases risks of soil erosion and nonpoint-source pollution and improves water quality (Lal and Follet, 2009). Nevertheless, changes in SOC stocks and dynamics can modify C transfer to other environmental compartments, such as the hydrosphere and the atmosphere (Lacoste et al., 2016), being an adequate soil management important to mitigate climate change (Lal, 2004), such as that promoted by agroforestry systems as pointed out by the Farm to Fork Strategy and the New EU Forest Strategy for 2030 (European Commission, 2021a, 2020a). More than 80% of the terrestrial carbon is expected to be in the soil, making it the largest terrestrial pool of organic carbon (Balbontín et al., 2009; Batjes, 2014), mainly because soil is the final destination of the vast majority of photosynthetic C fixed in terrestrial ecosystems (Rodríguez-Murillo, 2001), capturing approximately 20% of the annual man-made carbon emitted to the atmosphere (European Commission, 2005). Thus, according to Lacoste et al. DARÍO ARIAS MARTÍNEZ 48 Fig. 21. Soil water pH under each fertilization treatment from 2014 to 2016. NF: no fertilization, MIN: mineral; ANA: anaerobic sludge; COM: composted sludge and PEL: pelletized sludge. Different letters indicate significant differences among treatments within the same year. Bars in each column indicate the standard error of the mean. 5.4.1.2. Soil aggregate fractions Table 9 shows that the proportion of macroaggregates (250–2000 μm) in the topsoil increased from the beginning until the end of the studied period. However, the percentage of microaggregates (53–250 μm) and the silt + clay (<53 μm) topsoil fractions were lower in 2016 than in 2014. Regarding the effect of the treatments, COM in 2015 and PEL in 2015 and 2016 increased the percentage of microaggregates compared with NF (p<0.01) (Fig. 22), respectively. However, the percentage of macroaggregates was significantly higher in COM than in NF and PEL in 2016 (p<0.01). Fig. 22. Percentage of macroaggregates (250–2000 μm), microaggregates (53–250 μm) and silt + clay (<53 μm) under each fertilization treatment from 2014 to 2016. NF: no fertilization, MIN: mineral; ANA: anaerobic sludge; COM: composted sludge and PEL: pelletized sludge. Different letters indicate significant differences among treatments within the same soil aggregate fraction and year and treatments are not significantly different if letters are not shown. Bars in each column indicate the standard error of the mean. 5.4.1.3. Total topsoil Carbon The C concentration (g kg-1) and the C storage (Mg ha-1) in the whole soil significantly decreased over the years (Table 9). PEL treatment reduced the concentration and storage of C in the whole soil compared with NF and COM in 2014 (p<0.01) (Fig. 23). EFFECT OF DIFFERENT FERTILIZATION TREATMENTS 49 Similarly, total soil carbon stock was significantly lower in the case of PEL than in COM and NF in 2014 and NF in 2015. a b Fig. 23. Carbon concentration (g C kg-1) (a) and carbon storage (Mg C ha-1) (b) in the whole soil under each fertilization treatment from 2014 to 2016. NF: no fertilization, MIN: mineral; ANA: anaerobic sludge; COM: composted sludge and PEL: pelletized sludge. Different letters indicate significant differences among treatments within the same year and treatments are not significantly different if letters are not shown. Bars in each column indicate the standard error of the mean. 5.4.1.4. Fractionated soil Carbon The C concentration and C stocks associated with the macroaggregates increased over the years (Table 9) when all treatments are considered. However, the C concentration in the microaggregates and the silt + clay fractions were lower in 2016 than in 2014. The concentration and stocks of C associated with the macroaggregates were higher in the COM treatment than in ANA and PEL (p<0.05) but without differences with NF and MIN. A positive effect of the COM treatment on the C concentration in the macroaggregates compared to NF and PEL treatments was also observed in 2016 (p<0.05). The carbon stocks in the macroaggregate fraction was higher in COM than in ANA and PEL in 2014 and in NF than in the rest of the treatments in 2015, while no differences were shown in 2016. (p<0.05). a ab ab a b 50 55 60 65 70 75 80 85 NF MIN ANA COM PEL NF MIN ANA COM PEL NF MIN ANA COM PEL 2014 2015 2016 g C kg-1 Years and Treatments Whole soil a ab ab a b a ab ab ab b 100 110 120 130 140 150 160 170 180 190 200 NF MIN ANA COM PEL NF MIN ANA COM PEL NF MIN ANA COM PEL 2014 2015 2016 Mg C ha-1 Years and Treatments Whole soil C storage DARÍO ARIAS MARTÍNEZ 50 Silt+clay carbon stocks were significantly reduced in PEL and ANA compared with NF in the last year of the experiment (Fig. 24). Fig. 24. Carbon concentration (g C kg-1) (a) and carbon storage (Mg C ha-1) (b) in the three soil aggregate fractions (macroaggregates: 250–2000 μm, microaggregates: 53–250 μm and silt + clay: < 53 μm) under each fertilization treatment from 2014 to 2016. NF: no fertilization, MIN: mineral; ANA: anaerobic sludge; COM: composted sludge and PEL: pelletized sludge. Different letters indicate significant differences among treatments within the same soil aggregate fraction and year and treatments are not significantly different if letters are not shown. Bars in each column indicate the standard error of the mean. 5.4.2. Tree height and diameter Tree height and basal diameter were significantly affected by the year (p<0.001), with a decrease in January 2015 due to the coppicing made in April 2014 which was compensated by a rapid increase in March 2016 (Fig. 25). Regarding the effect of the fertilization treatments, MIN and ANA showed a higher tree height than COM in December 2013 (p<0.01). However, at the end of the experiment (March 2016), tree height was higher in MIN and PEL treatments compared with NF and COM (p<0.05). The tree diameter was increased in ANA in 2015 and ANA and PEL in 2016 compared with NF (p<0.05). 1 2 ab ab b a b bab ab a b 10 20 30 40 NF MIN ANA COM PEL NF MIN ANA COM PEL NF MIN ANA COM PEL 2014 2015 2016 g C kg-1 Years and Treatments Macroaggregates (250-2000 µm) Microaggregates (53-250 µm) Silt + clay (<53 µm) a abc ab c a bc abbbbaab bab b 10 30 50 70 90 NF MIN ANA COM PEL NF MIN ANA COM PEL NF MIN ANA COM PEL 2014 2015 2016 Mg C ha-1 Years and Treatments Macroaggregates (250-2000 µm) Microaggregates (53-250 µm) Silt + clay (<53 µm) b EFFECT OF DIFFERENT FERTILIZATION TREATMENTS 51 Fig. 25. Tree height (m) (a) and basal diameter (cm) (b) under each fertilization treatment in April and December 2013, January 2015 and March 2016. NF: no fertilization, MIN: mineral; ANA: anaerobic sludge; COM: composted sludge and PEL: pelletized sludge. Different letters indicate significant differences among treatments within the same year and treatments are not significantly different if letters are not shown. Bars in each column indicate the standard error of the mean. 5.4.3. Pasture production Annual pasture production, expressed as Mg of dry matter ha-1, was higher in 2015 than in 2016 (2015: 16.08a, 2016: 11.78b the different superscript letters indicate significant differences between the years) (p<0.001). The fertilization treatments significantly modified the pasture production in April 2015 harvest (p<0.05) (Fig. 26). In April 2015, pasture production was higher in COM (a) and MIN (ab) treatments than in PEL (bc), ANA (c) and NF (c). 1 2 ab aabab baab ab b baab ba 0 0.5 1 1.5 2 NF MIN ANA COM PEL NF MIN ANA COM PEL NF MIN ANA COM PEL NF MIN ANA COM PEL April 2013 December 2013 January 2015 March 2016 m Years and Treatments Tree height a bab aab ab bab aab a 0 1 2 3 4 NF MIN ANA COM PEL NF MIN ANA COM PEL NF MIN ANA COM PEL NF MIN ANA COM PEL April 2013 December 2013 January 2015 March 2016 cm Years and Treatments Tree diameter b DARÍO ARIAS MARTÍNEZ 52 Fig. 26. Pasture production (Mg dry matter ha-1) under each fertilization treatment. NF: no fertilization, MIN: mineral; ANA: anaerobic sludge; COM: composted sludge and PEL: pelletized sludge. * Indicates that in that harvest there were significant differences between treatments. Different letters indicate significant differences among fertilizer treatments within the same harvest and treatments are not significantly different if letters are not shown. 5.5. DISCUSSION In this study, the application of different types of sewage sludge increased soil water pH over time probably because soil water pH at the beginning of the study was lower than the pH of the fertilizers applied and due to the application of Ca and other cations made with these residues (López-Díaz et al., 2007; USDA, 2011), which can have impacts on C sequestration (Morris et al., 2007). However, another silvopastoral study fertilized with anaerobically digested sludge established under poplar (Populus x canadensis Moench) (FerreiroDomínguez et al., 2016a) found that the soil acidity was increased over time probably because they applied lime, which increased pasture production and thus cation extraction. On the other hand, the application of COM was the treatment that most raised the water pH value, as was also found by Ferreiro-Domínguez et al. (2018), Mosquera‐Losada et al. (2016) and Rigueiro‐Rodríguez et al. (2010) in different silvopastoral systems fertilized with the same types of sewage sludge and mineral fertilizers, probably explained by the lower mineralization rate and composition (mainly Ca) compared to ANA and PEL, that increases the COM liming capacity (Mosquera-Losada et al., 2010) and caused a longer effect in the soil mainly due to the higher woody composition (López-Díaz et al., 2007; RigueiroRodríguez et al., 2007). The higher proportion of microaggregates over the other two soil fractions found in the study was due to the fact that in the study area there is no tillage, which enhances the formation of stable microaggregates within macroaggregates because of its slower turnover, allowing the stabilization and sequestration of C in the long term (Denef et al., 2007; Six et al., 2000), since this disturbances may accelerate the C mineralization rate (Agnelli et al., 2008; USDA, 2009). The increase on the percentage of macroaggregates at the end of the study period can be explained by the higher input of leaves as trees grow up, whose mineralization increases the formation of new aggregates (Six et al., 2000) and the downward displacement of fine soil particles made by tree roots (Ferreiro-Domínguez et al., 2022). The higher percentage of macroaggregates at the end of the study period (2016) under the COM treatment was due to its high dry content and its lower mineralization rate, which contrasts with the higher percentage of microaggregates under the PEL treatment because of its higher mineralization rate compared to COM (Mosquera-Losada et al., 2010). EFFECT OF DIFFERENT FERTILIZATION TREATMENTS 53 The improvement of soil water pH led to an increase of the soil organic matter mineralization rate (Rigueiro-Rodríguez et al., 2011) and, consequently, to a reduction of C concentration and C storage in the whole soil over the years favored by an increase in the annual mean temperature and precipitation compared to previous years, which improved the metabolic rate of decomposer microorganisms (Mosquera-Losada et al., 2011; US-EPA, 1994). Additionally, as tree-pasture competition increases, it reduces pasture production and the subsequent root production, reducing the amount of C concentration in the whole soil (Guo and Gifford, 2002). The higher C concentration and C storage in the whole soil under COM compared to the other treatments is due to the lower N content of this residue (Mosquera-Losada et al., 2010) that limits mineralization and which causes a lower decomposition by decomposer organisms although soil water pH under this treatment was close to neutrality (Mungai and Motavalli, 2006). However, the low C concentration and C storage in the whole soil under PEL compared with the other treatments can be explained by the intermediate N values and the soil water pH, which is close to neutrality and favors mineralization. The low dose of mineral fertilization applied kept a high level of C storage in microaggregates because the input of N to the soil made with the fertilization probably reduced the C/N ratio, increasing the mineralization of existing SOM (Mosquera-Losada et al., 2015). Carbon storage and carbon concentration were on average higher in microaggregates because, according to Cong et al. (2017), the mass and organic C of microaggregates play an important role in aggregation and C accumulation and, since physical protection is much greater within microaggregates than within macroaggregates (Cabanettes et al., 1998; Pulleman and Marinissen, 2004), microaggregates can represent the majority of the soil C sequestration potential (Singh et al., 2015). Higher C concentrations in microaggregates in our study differs with the findings of Howlett et al. (2011a) in a silvopastoral cork oak dehesa, who found that macroaggregates accreted most C due to greater C inputs. This difference is understandable because their study trees were 80 years old that provide a huge amount of fresh plant material, which acts as a nucleation for the formation of macroaggregates (Gioacchini et al., 2016), while our trees were planted in 2013 and cut at ground level in 2014, thus the input of organic matter to the ground is much lower. The lowest C concentration found in the Silt + clay fraction (<53 μm) is due to the low or no binding capacity of SOC of the free silt particles (John et al., 2005). The quick increase in tree height and diameter after the coppicing made in 2014 was probably due to the already well developed tree root system into the soil after cutting and because trees grown in agroforestry systems usually grow faster than the same trees grown in forest ecosystems because of their lower density and because they also benefit from crop fertilization (Cardinael et al., 2018). Tree and pasture growth depended on the effect that different fertilizer treatments created in the soil and the effect that this new soil environment had on tree and pasture interaction as shown in other tree species such as ash, birch or radiata pine (Rigueiro-Rodríguez et al., 2012; Rigueiro‐Rodríguez et al., 2010). Tree response to fertilizer inputs depends on tree age and species. Tree height response to treatments was earlier than tree diameter due to tree physiology that makes the tree growing first on height and later on diameter. Walnut trees showed a good response to fertilization as found with red oak or ash (Ferreiro-Domínguez et al., 2011; Rigueiro‐Rodríguez et al., 2010) but behave differently to species that have longer harvest periods such as douglas fir (Ferreiro-Domínguez et al., 2018). This is due to the high growth rate of fast and medium growing tree species that makes the tree having an initial high nutrient needs and demand. DARÍO ARIAS MARTÍNEZ 54 Tree height was higher under MIN treatment due to the additional applications made in 2015 and 2016. Nevertheless, tree diameter was higher under ANA treatment after the coppice made in 2014 because the proportion of available nitrogen is higher than the other sludges (Mosquera-Losada et al., 2010). The higher 2015 pasture harvest compared to that of 2016 is probably explained because, according to Mosquera-Losada et al. (1999), the optimal relation between rainfall and temperature of 0.2 mm of rain per each centigrade degree was accomplished in 2015 summer and autumn, while in 2016 it was only accomplished in two winter months. In any case, the pasture production of this study was similar to the pasture production estimated by FerreiroDomínguez et al. (2011) and Ferreiro-Domínguez et al. (2014) in a similar area. The earlier PEL and ANA effect on soil fertility caused by the increase in N and P improved pasture production at the beginning of the experiment as shown by FerreiroDomínguez et al. (2018) and Rigueiro‐Rodríguez et al. (2010), so no pasture production differences between these treatments and NF was found three years after application. However the COM long term effect caused an initial low pasture production compared to ANA and PEL, which benefited the tree growth, because COM has a higher input of nutrients due to its lower nitrogen content, which makes it necessary to apply a higher amount of sludge, but its rate of decomposition is slower since it is mixtured with woody materials (Mosquera-Losada et al., 2010). The higher 2015 pasture production compared to that of 2016 is probably explained because MIN treatment was applied also in 2015 and 2016 all over the study area regardless the initial treatments, improving the effects of the sewage sludge in 2015, while in 2016 the effects of the different sludges mostly disappeared. 5.6. CONCLUSION Organic amendments can increase soil pH, especially when initial values are low, fostering a higher organic matter mineralization rate and consequently decreasing the C concentration and C storage in the whole soil, although the different fertilization treatments applied affected differently the soil properties depending on their composition, especially on nitrogen, which affects the decomposition and mineralization level of the organic matter. The deposition of leaves from the overstorey and its mineralization, along with the absence of tillage, promoted the formation of macroaggregates and microaggregates within them, boosting long-term C storage, especially in macroaggregates as tree biomass increases, benefited also from the fertilization made on the pasture, and the resulting higher plant debris production. The effect of sewage sludge fertilization lasts for few years, so it is advisable to carry out periodic treatments to promote pasture and tree growth and at the same time to recycle waste materials. 6.DISCUSSION 6.1. INNOVATION According to data from the Land Use and Coverage Area frame Survey (LUCAS) the area dedicated in the European Union in 2015 to agriculture was 179,646,600 Mha (41.1 % of the EU28 total surface) and 142,369,300 Mha (32.6 % of the EU28 total surface) dedicated to forestry (Eurostat, 2017b). Farmers and foresters are the first stewards of the natural environment and depend directly on these natural resources since farming provides regular work for 22 million persons directly and commodities for additional 44 million people considering the food sector. Moreover, rural areas are home to 55 % of EU´s citizens (European Commission, 2017), so agriculture and forestry are of huge importance in the European Union. In addition, agriculture contributes significantly to climate change, accounting for 9 % of the Union´s greenhouse gas emissions (European Commission, 2012a), and is in return severely affected by it, challenging current agricultural and forestry practices and production. Therefore, the Common Agricultural Policy (CAP) should lead a transition towards a more sustainable agriculture, boosting the knowledge creation and sharing by the creation of the European Innovation Partnership for Agricultural Productivity and Sustainability (EIP-AGRI) and the current CAPNetwork. The EIP-AGRI partnership and the CAPNetwork allow a better use of research results, ensuring that knowledge is shared and implemented and supporting the proliferation of modern technologies (European Commission, 2017) through innovation creation and dissemination. Rogers (2003) defines an innovation as an idea, practice, or object that is perceived as new to an individual or other social unit of adoption. According to the OECD (2005) an innovation is ‘the implementation of a new or significantly improved product (good or service) or process, a new marketing method, or a new organizational method in business practices, workplace or external relations’. The process to develop an innovation consists of all the decisions, activities and their impacts that occur from recognition of a need, challenge or problem, through research, development and commercialization of an innovation, through diffusion and adoption of the innovation by users, to its consequences (Rogers, 2003) and it typically involves different actors as researchers, farmers, advisors, agribusiness, retailers, non-profit organisations, etc (Krause et al., 2018). In this sense, the Innovation Union initiative, which is part of the Europe 2020 strategy, states that investments in research and innovation drive long-term growth since the rate of return for publicly funded research and development is considered high, driving the creation of smart, sustainable and inclusive growth (European Union, 2013c). The acceptance of the innovation development in the previous CAP fostered by the EIP-AGRI has led to a set of targeted initiatives as Mission Clima or Mission Soil across the EU. Due to changes in climate conditions, growing world population and scarcity of resources, research and innovation have to increase the adaptive capacity of plants, animals and production systems to produce more and more sustainably. This can be achieved by diversification and specific adaptation, mixed farming systems and land use practices, adaptation of plants, animals and cropping systems to biotic and abiotic stress, conservation and use of biodiversity, as well as specific climate change mitigation and stress adaptation measures at farm, forest and landscape level (European Commission, 2012b). Thus, innovations are especially important for farmers, since they are challenged to reduce the environmental impact of farming while ensuring economic viability and without greater farm profitability ecological sustainability will become even more challenging (European DARÍO ARIAS MARTÍNEZ 56 Commission, 2012a; Krause et al., 2018). That is why the research agenda of the European Union should clearly reflect the needs and contributions of rural areas (European Commission, 2017), providing more information on the costs and benefits of adaptation, as well as on the risks and uncertainties, vulnerabilities at local level, and the availability of data for monitoring and evaluation purposes to further support adaptation in European countries (European Environment Agency, 2017). Environmental policies and the Common Agricultural Policy (CAP) impact agricultural production and the agricultural sector is committed to meet these and other policies concerning trade, biodiversity, climate change, development and food security (European Commission, 2012b) so a good knowledge communication is essential. Moreover, the interaction of the research made by the different countries is needed in order to get the integration of the European research and innovation, avoiding overlapping and duplication of research. This transnational cooperation has often been developed with the support of European funding instruments, such as the Horizon 2020 programme (European Environment Agency, 2017) included in the European Innovation Partnership (EIP) for «Agricultural productivity and sustainability» which fosters innovation leading to a different growth path to establish a competitive and sustainable production of food, feed, fibre, biomass and biomaterial (European Commission, 2012a). The investment in research and innovation is also giving more emphasis on principles of agroecology and supporting farming systems that make efficient use of ecosystems services (e.g. organic farming, mixed farming, agroforestry) in the agri-food sector (European Commission, 2018b). In order to encourage uniformity among policies, reduce duplication and improve the speed and spread of innovation it is essential to have well-informed interaction between research and innovation and environmental policies as well as with involved stakeholders (European Commission, 2012b). The co-creation of knowledge between researchers and practitioners in a partnership stimulates the creation and diffusion of dedicated and usable innovations best fitted to the foreseen users (Krause et al., 2018; Schils et al., 2019) since innovation is a process or processes of change that occur as a result of interactions between multiple actors (Fielke et al., 2018) and are the basis for initiatives like the Operational Groups. Stakeholders may belong to different backgrounds, including farmers, businesses, industry, advisory services and NGOs embedded in a mix that allows and encourages room for open and honest dialogue to develop a shared vision of the future (Fielke et al., 2018) and to broadcast innovations (Krause et al., 2018) to put them into practice. The EIP-AGRI and the CAPNetwork seek to carry out these synergies by promoting the exchange among partners from different policy fields, sectors, initiatives and projects to contribute to higher effectiveness of existing policy instruments (European Commission, 2012a) Nevertheless, there is a gap between the provision of research results and the application of innovative approaches to farming practice (European Commission, 2012a) that may cause a lack of implementation of innovative approaches since normally new approaches take too long to arrive to the ground, and the needs of practical farming are not communicated sufficiently to the scientific community. Krause et al. (2018) reported several gaps and deficits that remain in innovation systems, such as: insufficiently linked research to practice and limited practical innovations stimulated by scientific novelty innovations or low integration of farmers into innovation systems. These means that farmers´ needs are not sufficiently considered and up-scaled while European countries perceive lack of resources (e.g. time, money and equipment) and uncertainties as the most important barriers (European Environment Agency, 2017). The adaptation of these knowledge gaps is addressed by EU- DISCUSSION 57 funded research (in particular through Horizon 2020 and Horizon Europe), which stimulates research and innovation by multi-actor projects funding. In order to overcome the knowledge transfer gap is essential to disseminate the science outcomes effectively, which will, at the same time, foster collaboration and innovation since innovations are successful when they reach a broad acceptance and adoption (Krause et al., 2018). Communication and dissemination will be of use in explaining the wider societal relevance of science, building support for future research and innovation funding, ensuring uptake of results within the scientific community, and opening up potential business opportunities for novel products or services (Scherer et al., 2018) while helping to scale knowledge up (increasing support by policies and markets for the innovation) and out (increasing number of users) (Turner et al., 2016). The results from this PhD show that although Thematic Networks are fundamental for promoting innovation at EU level, countries participation is not balanced, mainly due to differences in the proportion of land dedicated to the different farming types, the effort in research development and transfer, and the development of innovation and its transfer to the population. However, arable lands, which need more innovation due to its wider extension, were the main target of TNs as well as most relevant farm typologies. In order to increase sustainability, practices linked to value chains, bioeconomy and circular economy should be treated more thorough and extensively, supported by the creation of innovation documents and the creation of actors networks, that allow spreading and uptaking innovative practices. Moreover, TNs links with Operational Groups and National Rural Networks would promote networks, engaging relevant actors in the dissemination of innovation measures and knowledge transfer, helped by effective and well oriented communication actions. 6.2. CARBON SEQUESTRATION IN SILVOPASTORAL SYSTEMS SOILS Agroforestry is an integrated land-use system that follows the management model of ‘land sharing’ (i.e., the spatial integration between nature management and food production) which fosters synergies between the functions of conservation and production (Louah et al., 2017). Agroforestry land use area in 2012 in the EU 27 was 19.77 million ha, which corresponded to about 4.57 % of the territorial area and 10.84 % of the utilized agricultural area, corresponding 17.77 million ha to silvopasture (4.1 % of the territorial area in the EU), being southern European countries, and particularly Spain, those with highest representation in this type of agroforestry although there is huge potential for further implementation (den Herder et al., 2017; Mosquera-Losada et al., 2018). Its implementation involves environmental, social and economic benefits as well as disadvantages such as loss in farm income, reduced labour productivity and an increase in complexity of work (García de Jalón et al., 2018). Among the environmental benefits are a better water retention due to the presence of deeper root systems, a reduction in nutrient leaching to ground water that helps to retrieve nitrates and other nutrients that have leached below the rooting zone of herbaceous plants, establishment of better conditions for beneficial insects with consequences for soil composition and diversity of plants in the system, a reduction in greenhouse gas production along with an improvement of human health and health of farmers and farm workers as it is not an intensive farming practice (Broom et al., 2013; Lynde, 2020). 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