1,720,973 research outputs found
Feasibility of SRC Species for Growing in Mediterranean Conditions
No full textThe suitability of poplar (Populus × canadensis Moench.—genotype ‘Neva’), black locust (Robinia pseudoacacia L.), and eucalyptus (Eucalyptus bridgesiana R. Baker) growing in short rotation coppice (SRC) system in a Mediterranean area (southern Italy), and under two management regimes, was evaluated in terms of survival, biomass yield, biomass quality, and soil fertility. The high management regime (H treatment) consisted of high plant density (6667 trees ha−1) and a 2-year harvesting cycle; the low management regime (L treatment) consisted of low plant density (1667 trees ha−1) and a 4-year harvesting cycle. The dry biomass production was 36, 13, and 9 t dry matter (dm) ha−1 in the H treatment and 25, 14, and 7 t dm ha−1 in the L treatment for eucalyptus, black locust, and poplar, respectively. The analysis of the biomass showed a superior quality for the black locust feedstock because of its low moisture and ash percentages, high heating value (HHV), and low alkali metal concentrations, although, from an environmental point of view, the high N (12.3 g kg−1) and S (0.7 g kg−1) biomass concentrations would increase the pollutant emissions generated by combustion. Eucalyptus showed a high HHV, especially for the H treatment (18.70 MJ kg−1). Its high concentrations of K (4 g kg−1) and Mg (0.8 g kg−1) could provoke slagging and fouling in combustion equipment, and the high concentrations of S and N, if leaves are considered in the harvested biomass, indicate the low quality of its feedstock. No specific poplar feedstock stood out, although it had a good HHV (19.02 MJ kg−1). The soil fertility was not affected negatively after the 4-year SRC cycle, while S content in soil showed a tendency to increase in the case of black locust cultivation
Posidonia residues can be used as organic mulch and soil amendment for lettuce and tomato production
No full textInternational audienceThere is a need for sustainable fertilizers because common mineral fertilizers are increasingly costly and often induce water and air pollution. For instance, seagrass compost could be used as fertilizer in the coastal areas of the Mediterranean, thus also solving the issue of beached residues. Here, we studied organic fertilization by application of seagrass-based compost in a tomato and lettuce crop succession. Composts were made of posidonia and yard wastes at 1/4 w/w fresh weight ratio. Compost was applied at two concentrations: 10 and 20 Mg ha−1 fresh weight. Fresh leaves of posidonia were also tested directly as organic mulch in plots treated with conventional fertilizers. A control treatment involved mineral fertilization without mulching soil. Herbicide applications were performed in non-mulched plots immediately before transplanting of tomato and lettuce for controlling the weeds, while mulched treatments did not receive any herbicide application. Results show that 20 Mg ha−1 of posidonia-based compost is equivalent to the inorganic fertilization because the nutritional status and yield of tomato and lettuce were statistically similar. No phytotoxicity symptoms were observed in any of the tomato and lettuce plants mulched with posidonia. The same growth rate was observed for tomato and lettuce growing under conventional management practices: mineral fertilizer and herbicide applications. Overall, our findings show that seagrass-based compost is a promising, sustainable fertilizer for tomato and lettuce
Increasing the effective use of water in green asparagus through deficit irrigation strategies
No full textA six-year study was carried out to assess the effects of deficit (DI) and regulated deficit irrigation (RDI) strategies on yield and water use efficiency of two hybrids of asparagus (Asparagus officinalis L., hybrids Grande and Italo), in a typical semi-arid Mediterranean environment of Southern Italy. The experimental setup consisted of full irrigation (IRR; restoration of 100% of the crop evapotranspiration ET c ), DI (restoration of 50% of ET c from the first fern flush until the end of the growing season) and two RDI (1: no irrigation supply from the first fern flush, crop development stage more sensitive to water stress, until end of the growing season, RDI 1 ; 2: no irrigation supply from the second fern flush until the end of the growing season, RDI 2 ) treatments. The relationships between yield and water regimes in the multi-year dataset were analyzed using linear mixed effect models (LMM) taking into account residual autocorrelation and comparing different variance-covariance structures. Irrigation treatments affected significantly the asparagus productivity. The six-year average yield was highest under IRR treatment (6.4 t ha −1 ) and lowest under RDI 1 treatment (4.4 t ha −1 ). In comparison with IRR treatment, DI reduced ET c by 20% and yield by 13% (6-season average). Six-year average yields were similar in DI and RDI 2 treatments (5.6 and 5.4 t ha −1 , respectively). Asparagus yield varied with hybrid. Italo hybrid showed higher yield performances (5.6 t ha −1 ) respect to Grande (5.3 t ha −1 ). The soil water deficit tolerance, assessed through the “yield response factor” (Ky of the marketable yield), was 0.61 and this value indicates that asparagus is mildly negatively affected by sub-optimal irrigation regimes. On the contrary, irrigation water use efficiency (WUE I ) was clearly affected by the experimental treatment. WUE I was higher (2.8 kg m −3 ) if asparagus experiences the soil water shortage during the first fern flush (RDI 1 ). Operatively, full irrigation maximizes asparagus marketable yield, while reduced irrigation volume (DI or RDI 2 treatments) seems a promising strategy, since it allowed reducing on average the irrigation volume supplies by 34% with asparagus marketable yield loss by 13%
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Economic evaluation of hydrological ecosystem services in Mediterranean river basins applied to a case study in southern Italy
Get PDFLand use affects the eco-hydrological processes with consequences on extreme events such as floods and droughts. Changes in land use affect terrestrial ecosystems and their hydrological services. Spatial planning integrates the water resources governance in order to achieve the objectives of the water and floods European directives. The objective of this paper is the study of hydrological ecosystem services through the quantification of water resources, pollutant loads, land retention capacity and soil erosion. This evaluation allows assignment of an economic value to the ecosystemic services, and then the programming of compensatory actions to climatic or anthropogenic alterations. By assigning an economic value to natural resources (water and soil) and hydraulic system, the authors quantified the hydrological services provided by ecosystems of catchments using climate, hydrological and land use parameters. The proposed methodology to the basin "Bonis" (Calabria Region, Italy) has been applied. The authors have formulated three scenarios: variation between cultivated and forest areas, insertion of impermeable areas and alteration of the vegetation vigor. The simulations prove that the variations of the state of forest areas has a considerable influence on the quantity of water, and then on the economic value provided. Small economic changes occur in the introduction of reduced impermeable areas. A 50% rise of agricultural areas to the detriment of forest areas, increases soil erosion and reduces the storage capacity of the water. The proposed methodology can be a guideline for land planning choices
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