The release of phosphorus from heavily fertilized soils to dilute electrolytes: effect of soil properties

Soils heavily fertilized with P can contribute to the enrichment of P in surface runoff and can accelerate the eutrophication of streams and lakes. To describe this enrichment, information is needed on the capacity and rate of P release was characterized from soils. in Thus, 12 we carried out laboratory studies in which the release of P to a dilute electrolyte (0.002 M CaCl 2) widely different, heavily fertilized European soils. We studied: a) long-term P release under ’static’ conditions (in soil suspensions allowed to settle and left undisturbed for long periods); and b) short-term P release under ’turbulent’ conditions (rapidly stirred suspensions). The relationships between the amount of P released under static conditions and the solution/soil ratio (W) and time differed widely among soils. These differences were the probable result of differences in the content of the relatively soluble metal phosphates (capable of buffering P solution in the 10-6105M concentration range) and in the P adsorption capacity of the soils. The ratio between P released at 340 d for W = 10 000 and P exchanged isotopically at 1 d was generally > 2 in soils rich in soluble phosphates and with a high degree of surface saturation with P, while it was < 1 in soils with low surface saturation with P (acid soils with high P adsorption capacity). In soils rich in organic matter, the amounts of dissolved organic P and molybdate-reactive P released were comparable. Under turbulent conditions, the amount of P released after 2 h of soil-electrolyte contact ranged between 7 and 27 % of the P released at 340 d under static conditions. This stresses the importance that surface runoff and initial stream transport have in loading surface waters with P. The release of P under turbulent conditions was slower in acid sandy soils, where poorly crystalline Fe and Al oxides were the most important P adsorbents.Sols surfertilisés : libération de phosphore dans des électrolytes dilués. Les eaux de ruissellement prove- nant de sols surfertilisés peuvent conduire à l’eutrophisation des rivières et des lacs. Il est alors nécessaire de disposer de méthodes permettant de prévoir les vitesses de libération des phosphates à partir des particules de terre. Des études ont été entreprises au laboratoire avec douze sols européens surfertilisés mais de caractéristiques physico-chimiques très différentiées. La mise en solution du phosphore a été étudiée dans des solutions de CaCl 20,002 M en faisant varier le rapport solution-sol, W, de 10 à 10 000. Ces études ont été conduites dans deux directions: a) libération sur le long terme (340 j) et en conditions statiques; b) libération sur le court terme (2 h) et en conditions turbulentes. La quantité de P passée en solution en conditions statiques croît avec W et le temps de contact entre le sol et les solutions. La libération de P est fonction du contenu de phosphates solubles et de la capacité de rétention du P par les sols. Les quantités de P passées en solution pour W = 10 000 et durant 340 j sont élevées pour les sols pour lesquels la quantité de phosphore soluble et le degré de saturation sont élevés; elles sont faibles lorsque le degré de saturation du sol par les phosphates est peu élevé. Cette dernière situation est celle des sols acides à teneur élevée en matière organique; de plus, dans ces sols une fraction significative du phosphore passant en solution est sous forme organique. Dans les conditions turbulentes, les quantités de phosphore transférées dans la phase liquide en 2 h varient de 7 % à 27 % des quantités transférées à 340 j en conditions statiques. En conséquence la participation du phosphore durant la phase de transfert en surface vers les cours d’eau peut contribuer significativement à l’augmentation de la concentration du phosphore dans les eaux. La mise en solution du phosphore dans les conditions turbulentes semble plus lente dans les sols dont la rétention des phosphates serait contrôlée par des oxydes métalliques mal cristallisés

Claves de éxito para un reconocimiento eficaz

Sencillos, asequibles desde un punto de vista económico y, sobre todo, altamente rentables en términos de motivación, compromiso, productividad, etc. Los sistemas de reconocimiento empiezan a abrirse camino como una herramienta de gestión del talento, aunque sea todavía de manera informal en buena parte de las organizaciones

Controversy between curriculum design and curriculum development of online "highly specialized" education in the field of construction

Nowadays, on a global level, the Higher Education System has a complex and broad horizon of curricular tools to use in the teaching and learning process. In addition to these new educational instruments, full of possibilities, we face specific socio-economic conditions that affect in a significantly way the Curriculum Development in certain knowledge areas (areas traditionally built on a methodology based on a physical presence of students in the classroom). Some areas such as Restoration, Rehabilitation or Construction Pathologies, and the construction sector in general, require very defined and particular knowledge that only a small number of experts claim as specialized training. All these aspects condition the teaching methodology performed in a physical classroom at a university campus (the only option used until recent years) and made us consider the integration of online teaching in these areas too. The present work shows the teaching methodology used for the development of two online courses, where we offer distance learning for "highly specialized" formation in the Edification area (an area where traditionally there was only classroom training). At the beginning, both courses were designed by classroom training, but got a really small number of applications due to the specialized topic proposed. Later, we proposed a "Curriculum Redesign" of the contents, offering an online modality, which implied a significant demand both within and outside the university area. A notable feature of this educational experience is the great spectrum opened for attendees of both courses in the online version. This situation improved significantly the "Curriculum Development" for the student and implied an interesting new proposal on the offered contents and materials (what would have been really difficult to get in a face to face classroom). In conclusion, the absence of certain types of specialized contents in the academic university curricula makes essential to raise new methodologies to save the gap in this area through additional training courses as those analyzed in this paper. Thus, our experience opens a debate on the appropriateness of implementing online training in relation to the face to face training in constructive content subjects and, especially, presents a new scheme, not without controversy, for the curriculum design

Teaching-learning process of historical heritage: a Journey as a beginning, path and end

The implantation of new university degrees within the European Higher Education Area implies the need of innovative methodologies in teaching and learning to improve the skills and competencies of students and to answer the growing needs that society continuously demands to heritage management experts. The present work shows an application of the teaching methodology proposed during the international workshop entitled “I International Planning Preservation Workshop. Learning from Al Andalus”, which included the participation of the University of Alicante and Granada, Università Politecnico di Milano and Hunter College City University of New York; where we tried to dissolve traditional boundaries derived of interuniversity cooperation programs. The main objective of the workshop was to discuss and debate the role of urban Historical Centers within the Global Heritage by the integrated work through multidisciplinary teams and the creation of a permanent international working group between these universities to both teach and research. The methodology of this workshop was very participatory and considered the idea of a new learning process generated by "a journey experience." A trip from global to local (from the big city to the small village) but also a trip from the local (historical) part of a big city to the global dimension of contemporary historical villages identified by the students through a system of exhibition panels in affinity groups, specific projects proposed by lecturers and teachers or the generation of publications in various areas (texts, photographs, videos, etc.). So, the participation of the students in this multidisciplinary meeting has enhanced their capacity for self-criticism in several disciplines and has promoted their ability to perform learning and research strategies in an autonomous way. As a result, it has been established a permanent international work structure for the development of projects of the Historical City. This relationship has generated the publication of several books whose contents have reflected the conclusions developed in the workshop and several teaching proposals shared between those institutions. All these aspects have generated a new way of understanding the teaching process through a journey, in order to study the representative role of university in the historical heritage and to make students (from planning, heritage management, architecture, geography, sociology, history or engineering areas) be compromised on searching strategies for sustainable development in the Contemporary City

Factors determining Zn availability and uptake by plants in soils developed under Mediterranean climate

Zinc deficiency is an extended agronomic problem, particularly in staple food crops such as cereals. The availability of Zn to plants is ruled by soil properties, biological factors in the rhizosphere, and interaction with other nutrients. These factors may constrain the predictive value of Zn availability indices. This work aimed at assessing the soil factors that affect the absorption of Zn by plants and improving the predictive value of conventional indices. To this end, an experiment was performed using durum wheat (Triticum durum L.) grown on a set of soils developed under Mediterranean climate. In calcareous soils, Zn uptake by plants decreased with increased clay content and Olsen P (POlsen), meanwhile in non-calcareous soils it decreased with increased crystalline Fe oxides content. Biological factors such as microbial activity and organic anion exudation in the rhizosphere contribute to Zn uptake by plants. No relationship was found between Zn uptake by plants and the DTPA extractable Zn (ZnDTPA). Pyrophosphate extractable Zn (ZnPyro) was only related to Zn uptake by plants in calcareous soils (R2 = 0.29; P < 0.01). The best estimation of Zn uptake by plants in calcareous soils was obtained with a model involving ZnPyro/POlsen ratio and clay content (R2 = 0.57; P < 0.001). In non-calcareous soils, Zn uptake by plants was accurately estimated with a model involving Fe bound to crystalline oxides and rhizospheric oxalate (81% of the variance explained). Results reveal the need of discriminating soils according to its carbonate content and the use of soil properties related to Zn adsorption capacity, such as clay and Fe oxide content, and Olsen P for accurate estimation of Zn uptake by plants

Effect of Zn binding to phytate and humic substances on its uptake by wheat (Triticum durum L.) as affected by carbonates and Fe oxides

Although complexation with soil organic matter may improve zinc (Zn) bioavailability to plants, the effect of Zn sorbent surface on the use of complexed Zn by plants remains unknown. The objective of this research was to elucidate how Zn complexation with humic substances (HS) and phytate affects the uptake of Zn by wheat plants depending on the main sorbent surface in growth media, i.e., carbonates and Fe oxides. To this end, two pot experiments were performed, one using Fe oxide-coated siliceous as the siliceous growth medium sand and the other using a mixture of calcareous sand and siliceous sand as the calcareous growth medium. Each experiment involved three Zn sources, Zn-HS complex, Zn phytate, and ZnSO4. All sources were applied with surface irrigation at two Zn rates (0.25 and 2 mg kg−1 growth medium). The Zn-HS complex significantly increased Zn uptake by plants in both media, relative to the other two Zn sources, but no significant difference was observed between Zn phytate and ZnSO4. In the calcareous medium, Zn-HS complex and Zn phytate resulted in significantly higher dry biomass yields of wheat than ZnSO4. In the siliceous medium, spike and shoot dry biomass yields with Zn-HS complex at the low rate and Zn phytate at both rates were not significantly different from those with ZnSO4 at the high rate. After harvest, approximately 50% of the Zn applied as Zn-HS complex remained extractable by diethylenetriaminepentaacetic acid (DTPA), while this proportion was less than 20% for the other Zn sources. Thus, Zn-HS complex and Zn phytate are sources of available Zn for plants, and they are more effective than ZnSO4 in increasing plant growth, particularly when carbonates are the main Zn sorbent surface

Tourism and hospitality sector electricity use: evidences from 12 EU countries

At the Paris Conference of the Parties (COP21) in 2015, 195 countries agreed to strengthen the global response to the threat of climate change. Along this line, the EU is committed to a 40% reduction in their domestic greenhouse gas emissions by 2030. This new target represents a significant progression beyond its existing 20% emission reduction commitment by 2020. Thus, greater efforts will be needed affecting all productive sectors in order to reduce CO2 emissions and energy consumption. In order to reach this ambitious target, new measures affecting all economic sectors would be needed. This paper focuses on the tourism sector. This aim of this study is to investigate the relationships between tourist overnight stays and the hospitality sector electricity consumption. These relationships are studied for 12 EU countries during the period 2005-2012, accordingly with the available data. With this aim, econometric panel data techniques are used in order to estimate an electricity consumption function for the hospitality sector which depends on tourism, income, price and climate variables. The Environmental Kuznets Curve hypothesis is also tested. An Energy-tourism Kuznets Curve would show that increasing earnings from tourism will bring about reduced electricity consumption from a threshold point, which could be related to the fact that more earnings could imply undertaking more energy efficiency measures

Calculation of threshold Olsen P values for fertilizer response from soil properties

Phosphorus (P), a non-renewable resource, needs to be used more efficiently in agriculture. This requires using soil P tests. However, the P test threshold values for fertilizer response depend on many soil properties, some of which may be useful to estimate these threshold values, others not. Therefore, we searched here which soil properties are useful to estimate P threshold values. We calculated the threshold values for Olsen P and 0.01 M CaCl2 extractable P of 18 representative agricultural soils of the Mediterranean region of Spain. For that, we performed a P starvation experiment in which wheat and sunflower were alternatively pot-cropped. Results show that Olsen P threshold values are negatively correlated to P buffer capacity (r of −0.74, P lower than 0.001), clay content (−0.82, 0.001), pH (−0.76, 0.001), and Fe oxide content (−0.55, 0.05). Multiple regression models involving clay, pH or soil organic C, and phosphatase activity or organic hydrolysable P accounted for as much as 87 % of the variance in calculated Olsen P threshold values. In particular, there is a major effect of organic P on Olsen P threshold values. Single models based on routinely measured soil properties such as clay content and pH made accurate predictions of Olsen P threshold values with r 2 of 0.81 and P lower than 0.001

Teaching Innovation in Order to Integrate Self-Learning and Self-Evaluation in the Webct Platform

El concepto de docencia universitaria tradicional se ha visto modificado por los principios definidos en el Espacio Europeo de Educación Superior. Un cambio metodológico que motiva el concepto de autoevaluación y promueve todas aquellas actividades académicas que faciliten el autoaprendizaje. En este escenario, es fundamental que los estudiantes adquieran nuevos hábitos autoformativos. Nuestro trabajo presenta un método de enseñanza-aprendizaje para que ésta pase a ser más activa y participativa. Este proyecto permite al alumno disponer de un conjunto de recursos, que favorecen la autoevaluación y autoformación, a la vez que facilita su trabajo personal y en equipo.In the European Higher Education Area (EHEA) the traditional teaching university concept has changed. EHEA has introduced a methodological change in order to motivate selfevaluation and to promote self learning academic activities. In this way students must acquire new self learning practices. Our work presents a method to make more active and participatory the teaching-learning process. This project provides students different tools in order to promote the self-learning and self-evaluation. A set of teaching resources are presented to facilitate both individual and collective students' work

A Precise Electrical Disturbance Generator for Neural Network Training with Real Level Output

Power Quality is defined as the study of the quality of electric power lines. The detection and classification of the different disturbances which cause power quality problems is a difficult task which requires a high level of engineering expertise. Thus, neural networks are usually a good choice for the detection and classification of these disturbances. This paper describes a powerful tool, developed by the Institute for Natural Resources and Agrobiology at the Scientific Research Council (CSIC) and the Electronic Technology Department at the University of Seville, which generates electrical patterns of disturbances for the training of neural networks for PQ tasks. This system has been expanded to other applications (as comparative test between PQ meters, or test of effects of power-line disturbances on equipment) through the addition of a specifically developed high fidelity power amplifier, which allows the generation of disturbed signals at real levels.Ministerio de Ciencia y Tecnología DPI2006-15467-C02-0