El nostre llegat agrícola

Llavors tradicionals de l'horta nor

Balance de macronutrientes y materia orgánica en el suelo de agrosistemas hortícolas con manejo integrado y ecológico.

RESUMEN La intensificación de la producción agrícola en los últimos cuarenta años ha provocado un notable aumento de la cantidad de alimento producido, a costa de provocar un elevado coste medio ambiental. Como problemas comunes asociados a las prácticas agrarias implantadas con el modelo actual de agricultura intensiva se encuentran la eutrofización y pérdidas de biodiversidad, lixiviación de nitratos y contaminación de las aguas subterráneas, degradación de la estructura del suelo, enfermedades incontroladas y contaminación por pesticidas, etc. Además, este modelo de producción generalmente genera desequilibrios nutricionales, lo cual no es sostenible a largo plazo. Por ello, es conveniente adaptar la agronomía a unas prácticas que sean compatibles con el uso sostenible de los recursos naturales. Como respuesta a esta necesidad de formas más sostenibles de producción agrícola ha surgido la agricultura ecológica y más recientemente, la producción integrada. El principal objetivo de estos modelos de producción es desarrollar sistemas agrícolas que sean más sostenibles en términos agronómicos, ambientales y económicos, así como asegurar la producción de alimentos de elevada calidad de forma respetuosa con el medio ambiente. El presente trabajo está enmarcado en el seno de un proyecto europeo denominado VEGINECO, cuyo propósito es el desarrollo, ensayo, evaluación y comparación de prototipos agrarios de hortícolas basados en técnicas de manejo de producción integrada y ecológica. El objetivo fundamental de este estudio ha sido el cálculo de los balances simplificados de nutrientes y de materia orgánica a lo largo de una rotación de cultivos hortícolas en sistemas de producción integrada y ecológica durante tres años, con la finalidad de aportar una información útil que permita ajustar el abonado a las necesidades nutritivas reales de los cultivos, evitando así los excesos que se suelen cometer en la agricultura intensiva, que suponen un gasto innecesario para el agricultor y que son una importante fuente de contaminación ambiental. Por ello, se ha evaluado la idoneidad de los balances de nutrientes (N, P, K y Mg) y de materia orgánica para su empleo como indicadores de sostenibilidad de los agrosistemas y posibles herramientas para el cálculo de la fertilización. A su vez, se ha comparado la evolución de éstos balances teóricos con la de los contenidos de nutrientes asimilables en el suelo, con el fin de comprobar si existe una relación directa entre ellos. Este estudio podrá servir de orientación para futuras reconversiones a sistemas de agricultura más sostenibles, ya que con el rendimiento de la cosecha obtenida también incluido en el presente trabajo, además de evaluar el efecto del manejo sobre la producción, se podrá tener una idea aproximada de la cuantía de las extracciones de nutrientes que ocasionan los cultivos en diferentes zonas de la Comunidad Valenciana, permitiendo así cuantificar las necesidades de fertilización de los cultivos hortícolas en estos sistemas de producción integrada y ecológica. ____________________________________________________________________________________________________The intensification of agricultural production over the last forty years has strongly increased the amount of food obtained, although it has also had as a consequence a high environmental cost. Eutrophication and biodiversity losses, nitrate leaching and groundwater pollution, degradation of soil structure, uncontrolled diseases and pesticides contamination are common problems associated with conventional cropping systems. For this reason, it is important to consider the convenience of using management practices compatibles with the sustainable use of resources. Two more sustainable ways of production are organic farming and more recently integrated production organic. This work was included in the large-scale EU project VEGINECO, which focused on research into horticultural systems to develop, test, evaluate and compare prototypes of integrated and ecological vegetable farming systems. The main objective of this study was to calculate simplify macronutrients (N, P, K, Mg) and organic matter balances for integrated and organic systems during three years in a crop rotation. These results could give an important information to improve fertilization programmes, adjusting the inputs to the real nutrient requirements and avoiding the common surpluses in intensive agriculture. Furthermore, these additionally inputs increase unnecessary costs to the farmers and they are an important focus of environmental pollution. For this reason, it has been consider the convenience of using nutrient balances as environmental indicators and as tools for nutrient management. Additionally, these theoretic balances were compared to the evolution of available nutrient reserves in soil systems to prove if there is any direct relation between them. This study could be very useful to get further information about patterns of respectful agriculture, due to with the results of crop production included in this experience, moreover we can evaluate the effects of the management in production, we can determinate the absorption of nutrients on some species of vegetables in different areas of Valencian Community, as advisory criteria for the nutrient necessities in crops in integrated and organic systems

Trawling-induced daily sediment resuspension in the flanks of La Fonera Canyon

VIII Congreso Geológico de España (Oviedo, 2012). -- 4 pages, 3 figures[ES] El impacto de la pesca de arrastre en los fondos marinos y sus recursos naturales ha adquirido creciente relevancia durante las últimas décadas. Sin embargo, su posible contribución a la dinámica sedimentaria contemporánea permanece poco estudiada. Una línea equipada con sensores de turbidez fue fondeada a 1000 metros de profundidad en un tributario del flanco norte del Cañón de la Fonera (=Palamós), el cual es explotado por una flota de arrastre a profundidades entre 400 y 800 m. Durante días y horas de trabajo únicamente, se detectaron plumas de turbidez de un espesor mínimo de 100 metros, con concentraciones de sólidos en suspensión hasta 200 mg l-1 cerca del fondo, 1-2 órdenes de magnitud superiores a los valores medidos en días sin actividad pesquera. Estos incrementos de turbidez observados a distancia de los caladeros están asociados a flujos de gravedad generados por las pesadas artes de arrastre. Los resultados muestran que la pesca industrial de arrastre puede modificar dramáticamente los patrones naturales de resuspension y transporte de sedimento en márgenes continentales, principalmente en fondos de elevada pendiente como los flancos de cañones submarinos[EN] The offshore displacement of commercial bottom trawling has raised concerns on the impacts of this activity over the deep-sea physical environment, but the issue still remains largely unaddressed. A focussed study to address the alteration of natural sediment fluxes by trawling activities was conducted at the northern flank of the La Fonera Canyon (northwestern Mediterranean), where a bottom trawling fishery is active at depths from 400 to 800 m. A moored line equipped with turbidimeters at several heights over the seafloor was deployed at 1000 m depth to document the downslope effects of trawling on water turbidity. During working days and working hours of the trawling fleet, plumes of resuspended sediment extending to at least 100 m above the bottom were observed, with near-bottom suspended sediment concentrations up to 200 mg l-1. In the absence of trawling, turbidity dropped back to background levels ~2 mg l-1. These results highlight that, in steep environments such as the flanks of submarine canyons, the effects of bottom trawling on sediment resuspension and water turbidity can propagate to larger and deeper areas than the fishing grounds and dramatically change the natural patterns and rates of resuspension and advection of sedimentsEl proyecto HERMIONE fue financiado por la Comisión Europea (FP7 Grant agreement no: 226354). J. Martín se benefició de una beca FPI (MEC) y un contrato del programa JAE-DOC (CSIC)Peer reviewe

Phosphomonosterase and dehydrogenase activities in a horticulture soil under integrated and organic management

The effect of integrated and organic management on the levels of dehydrogenase and alkalyne phosphomonosterase (EC 3.1.3.1) activities was determined in a horticultural soil during a four year crop rotation, finding no statistically-significant differences. Since soil tillage and fertilization were similar, the absence of effects suggests that the well-reasoned use of small rates of agrochemicals in the integrated management for weed and pest control may have negligible effects on soil microbiological activity

Variability of Shelf Growth Patterns along the Iberian Mediterranean Margin: Sediment Supply and Tectonic Influences

Clinoform depositional features along the Iberian Mediterranean margin are investigated in this study, with the aim of establishing the causes of their varied shapes and other characteristics. We have analyzed the broad-scale margin physiography and seismic stratigraphic patterns based on high-resolution bathymetric data and previously interpreted seismic data. In addition, we have evaluated regional supply conditions and the uplift-subsidence regime of the different shelf sectors. The upper Quaternary record is strongly dominated by shelf-margin regressive wedges affected by the prevailing 100 ka cyclicity. However, the margins exhibit considerable lateral variability, as the result of the balance between the amount of sediment supply and the uplift-subsidence relationship. Three major shelf sectors with distinct morpho-sedimentary features have been defined. The relatively narrow northern shelves (Roses, La Planassa and Barcelona) are supplied by discrete river outlets that collectively constitute a linear source and are mainly affected by tectonic tilting. The wide middle shelves (Ebro Shelf, the Gulf of Valencia, and the Northern Arc) receive the sediment supply from the large Ebro River and other medium rivers. Although the tectonic regime changes laterally (strong subsidence in the north and uplift in the south), shelf growth is maintained by lateral advection of sediments. The southern shelves (the Southern Arc and the northern Alboran Shelf) are very abrupt and narrow because of the uplifting Betic Cordillera, and the torrential fluvial regimes that determine a very efficient sediment by-pass toward the deep basin. Submarine canyons deeply incised in the continental margin constitute a key physiographic feature that may enhance the transport of sediment to the deep sea or individualize shelf sectors with specific sedimentation patterns, as occurs in the Catalan margin.This research was funded by the Spanish Ministry of Economy, Industry and Competitiveness projects CGL2011-30302-C02-02, CGL2015-74216-JIN, CTM2015-65142-R and CTM2017-88237-P

Evolution of marine gravel dunes on the open shelf under multi-directional currents conditions

On inner continental shelves, a variety of coarse grained bedforms, such as gravel dunes, are shaped by hydrodynamic and morphodynamic processes. The formation and evolution of bedforms reflect a balance between seabed and coastal morphology, sediment type and availability, and regional hydrodynamics. Yet, observing bedform evolution directly in the marine environment is rare, mostly due to the lack of repeat seafloor mapping surveys. In this study we use repeat bathymetry from 3 surveys over 4 years from the western Cook Strait/Te Moana-o-Raukawakawa region, New Zealand/Aotearoa. We integrate seabed morphology characterisation with sediment classification and regional hydrodynamic modelling, to investigate the evolution of gravel dunes under multi-directional current conditions. The repeat seafloor mapping reveals morphological changes to plan-view dune geometry and bifurcation of crestlines, with maximum observed vertical changes up to 3 m at water depths between 60 and 80 m. However, no dune migration was detected. Our hydrodynamic model shows that the most prominent morphological changes over the gravel dunes are spatially correlated with eddy formation, and high multi-directional near-bottom currents, reaching maximum speeds of ∼4 m s−1 and bottom stress of >25 N m−2 in each tidal cycle. We demonstrate that the average hydrodynamic conditions in this region are capable of mobilising coarse-grained sediment (i.e., sand to gravel), indicating that the observed morphological changes over multi-year time scales are a result of continuous remobilisation by currents, rather than extreme or storm events. Our findings demonstrate the highly dynamic nature of the seabed in Cook Strait, and the need for regular, repeat mapping surveys to ensure up-to-date seabed morphology information

Actividades enzimáticas en suelos después de distintas modalidades de gestión de la paja de arroz

Severe problems are caused by site burning of rice straw in Valencia, the third largest Spanish city. Removal, incorporation or composting are being tested as alternatives to burning, and the changes they produce in selected soil biological properties have been studied in two field trials. One compares removal, burning and incorporation the straw, and a second evaluates the application of straw-derived compost for rice production. No statistically-significant effects on the measured indicators of biological activity were found in either experiment, indicating that management-induced changes are small. Unexpectedly, burning did not affect negatively enzyme activities or microbial biomass contents since there were no differences between treatments, or usual levels were recovered in a few months. The changes induced by straw removal or incorporation were also not statistically significant. When straw-derived compost applications were assayed, dehydrogenase activity was slightly variable and apparently unaffected by N and compost rates or compost/mineral N combinations, but phosphomonosterase activity seems to increase parallel to compost to mineral N ratioLa quema de la paja de arroz en Valencia, tercera ciudad española, está causando severos problemas. Diversas prácticas de manejo como la retirada, la incorporación al suelo o el compostaje de la misma están siendo ensayadas como alternativas a la quema. Para el estudio de los cambios que estas prácticas generan en algunas propiedades biológicas de los suelos se han realizado dos ensayos en parcelas experimentales. El primer ensayo compara la retirada, quema e incorporación de la paja, como distintas formas de manejo de la misma, y el segundo ensayo evalua el efecto de la aplicación de un compost de paja de arroz en el suelo del arrozal. No se encontraron diferencias estadísticamente significativas en las medidas de actividad biológica en ninguno de los dos ensayos, indicando que la modalidad de manejo de la paja tan solo induce pequeños cambios en el suelo. Sorprendentemente, la quema no afectó a las actividades enzimáticas ni a la biomasa microbiana del suelo, ya que no se observaron diferencias entre tratamientos, o puede que se recuperaran los niveles usuales en pocos meses. Asimismo, en el ensayo de la aplicación del compost de la paja de arroz, se observó una ligera variación en la actividad deshidrogenasa, pero aparentemente no le afectaron ni la dosis de compost aplicada ni la combinación conjunta de fertilización mineral y fertilización orgánica. Sin embargo, la actividad fosfomonoesterasa pareció incrementar de forma paralela con las dosis aplicación de compost/fertilización mineralS

Space-for-time substitution and the evolution of submarine canyons in a passive, progradational margin

European Geosciences Union General Assembly 2013, 7-12 April, Vienna, Austria.-- 1 page40% of submarine canyons worldwide are located in passive margins, where they constitute preferential conduits of sediment and biodiversity hotspots. Recent studies have presented evidence that submarine canyons incising passive, progradational margins can co-evolve with the adjacent continental slope during long-term margin construction. The stages of submarine canyon initiation and their development into a mature canyon-channel system are still poorly constrained, however, which is problematic when attempting to reconstruct the development of passive continental margins. In this study we analyse multibeam echosounder and seismic reflection data from the southern Ebro margin (western Mediterranean Sea) to document the stages through which a first-order gully develops into a mature, shelf-breaching canyon and, finally, into a canyon-channel system. This morphological evolution allows the application of a space-for-time substitution approach. Initial gully growth on the continental slope takes place via incision and downslope elongation, with limited upslope head retreat. Gravity flows are the main driver of canyon evolution, whereas slope failures are the main agent of erosion; they control the extent of valley widening, promote tributary development, and their influence becomes more significant with time. Breaching of the continental shelf by a canyon results in higher water/sediment loads that enhance canyon development, particularly in the upper reaches. Connection of the canyon head with a paleo-river changes evolution dynamics significantly, promoting development of a channel and formation of depositional landforms. Morphometric analyses demonstrate that canyons develop into geometrically self-similar systems that approach steady-state and higher drainage efficiency. Canyon activity in the southern Ebro margin is pulsating and enhanced during sea level lowstands. Rapid sedimentation by extension of the palaeo-Millars River into the outermost shelf and upper slope is inferred as the source of gravity flows driving canyon evolution. Canyon morphology is shown to be maintained over the course of more than one fall and rise in sea-level. Our model of canyon evolution is applicable to other passive margins (e.g. Argentine continental margin)Peer Reviewe

Space-for-time substitution and the evolution of submarine canyons in a passive, progradational margin

40% of submarine canyons worldwide are located in passive margins, where they constitute preferential conduits of sediment and biodiversity hotspots. Recent studies have presented evidence that submarine canyons incising passive, progradational margins can co-evolve with the adjacent continental slope during long-term margin construction. The stages of submarine canyon initiation and their development into a mature canyon-channel system are still poorly constrained, however, which is problematic when attempting to reconstruct the development of passive continental margins.peer-reviewe

Large sediment waves over the Gulf of Roses upper continental slope (NW Mediterranean)

Large sediment waves have been observed over the Gulf of Roses (GoR) continental slope (NW Mediterranean), developed between similar to 200 and similar to 400 m water depth. Geometric parameters computed from the acquired swath bathymetry revealed mean wave lengths of similar to 2000 m, and maximum wave heights of similar to 60 m. Single-channel reflection seismic profiles provided information on the sediment wave internal structure and the Quaternary stratigraphic architecture of the GoR outer shelf and slope. Seven main seismic units could be identified, with continuous development of sediment waves over the outer continental shelf and upper slope, showing differences in wave height and length. The seismic units are differentiated by erosional surfaces that can be followed from the outer shelf down the slope, and which have been correlated with Pleistocene eustatic oscillations. Sediment cores were collected over the sediment wave crests and troughs, and grain size distribution and sediment accumulation rates were analysed. Results show a dominant fraction of fine sediments, allowing classifying the observed bedforms as mud waves. Calculated sediment accumulation rates ranged between 0.08 and 0.18 cm/y, with no clear sedimentation pattern (e.g. differential sediment deposition rates) observed between wave crests and troughs. Nevertheless, the presence of thick surface mixed layers and the increase of the sand fraction in the upper sections of the cores indicate that the surface sediments are affected by bottom trawling activities, since the area is highly impacted by this human activity. The sediment waves observed over the GoR slope are most likely to be formed by bottom currents generated by overflows of dense water originated in the Gulf of Lions shelf, which cascade downslope in an oblique angle with respect the main bathymetric contours. This study offers new insights on the role of dense shelf water cascading processes and associated off-shelf sediment transport reshaping the morphology of the open-slope regions