1,721,031 research outputs found
Abundance and biodiversity of soil microarthropods as influenced by different types of organic manure in a long-term field experiment in Central Spain
No full text8 pages, figures, and tables statistics.We studied the effects of long-term organic and mineral fertilization on soil microarthropods and soil chemical parameters in a
field experiment under semi-arid conditions in Central Spain. Two different regimes of organic manuring, i.e. farmyard manure
applied once in 3 years versus annual manuring with crop residues were compared. Soil carbon and nitrogen contents were
increased markedly by farmyard manure, whereas straw and green manure had no significant effect. In contrast, the abundance of
soil microarthropods was increased by annual application of straw and green manure, but not by farmyard manure last applied 2.5
years before sampling.We conclude that in the field experiment under study the abundance of soil microarthropods was influenced
by the immediate food supply rather than by soil chemical parameters, such as carbon and nitrogen content or the pH. Biodiversity
of soil microarthropods, as estimated by the Shannon index, was not affected significantly by straw and green manure. Obviously,
other management practices, especially tillage, are limiting the species composition of soil microarthropods and thereby
overshadow possible effects of fertilization on diversity.We are grateful to Dr. Elke Schulz (Centre for
Environmental Research, Leipzig-Halle) for doing the
soil chemical analysis and to the staff of ‘‘La Higueruela’’
experimental station for supporting us during our field
work. The first author was supported by the German
Academic Exchange Service (code D/01/02687).Peer reviewe
Microbial activity in a sandy arable soil is governed by the fertilization regime
No full textKeywords: soil microbial biomass / soil basal respiration activity / dehydrogenase activity / cellulase activity / organic manuring / nitrogen fertilization / long-term field experiment. - The aim of this study was to compare the influence of two different long-term organic fertilization regimes at an arable site on a nutrient-poor, sandy soil with respect to soilmicrobial biomass contents and microbial activities. The investigation was performed on a long-term experimental arable field site, located in the semi-continental climate of Central Europe (IOSDV, Berlin-Dahlem, Germany). Soil microbial biomass and dehydrogenase activity were most clearly increased by combined straw and green manure treatment. In comparison, farmyard manure had a weaker effect, explained by less frequent applications and different quality of organic materials incorporated into soil. The mineral N-fertilization did not significantly effect microbial biomass content or dehydrogenase activity of the soil under study. The cellulase activity was increased markedly by straw and green manure treatment, but was increased only slightly by mineral fertilization. Organic manuring with plant residues had a stronger impact on soil microbial activity as compared to different soil sampling dates. We conclude that soil microbial activity was governed most clearly by the fertilization regime under the conditions of the investigated field experiment. Furthermore, manuring with plant residues has the most beneficial effects on soil quality among the investigated types of fertilisation
Abundance and biodiversity of soil microarthropods as influenced by different types of organic manure in a long-term field experiment in Central Spain
No full textMicrobial activity in a sandy arable soil is governed by the fertilization regime
No full textKeywords: soil microbial biomass / soil basal respiration activity / dehydrogenase activity / cellulase activity / organic manuring / nitrogen fertilization / long-term field experiment. - The aim of this study was to compare the influence of two different long-term organic fertilization regimes at an arable site on a nutrient-poor, sandy soil with respect to soilmicrobial biomass contents and microbial activities. The investigation was performed on a long-term experimental arable field site, located in the semi-continental climate of Central Europe (IOSDV, Berlin-Dahlem, Germany). Soil microbial biomass and dehydrogenase activity were most clearly increased by combined straw and green manure treatment. In comparison, farmyard manure had a weaker effect, explained by less frequent applications and different quality of organic materials incorporated into soil. The mineral N-fertilization did not significantly effect microbial biomass content or dehydrogenase activity of the soil under study. The cellulase activity was increased markedly by straw and green manure treatment, but was increased only slightly by mineral fertilization. Organic manuring with plant residues had a stronger impact on soil microbial activity as compared to different soil sampling dates. We conclude that soil microbial activity was governed most clearly by the fertilization regime under the conditions of the investigated field experiment. Furthermore, manuring with plant residues has the most beneficial effects on soil quality among the investigated types of fertilisation
Chloride Changes Soil–Plant Water Relations in Potato (Solanum tuberosum L.)
No full textThere is evidence that chloride (Cl―) can lead to both an improved hydration and water use efficiency in plants due to its osmotic properties. The potato crop is widely assumed to be sensitive to Cl―. This is based on studies which found tuber yield or tuber starch reductions following a Cl― fertilization. However, there are also contradictory reports which could not find any detrimental effect of Cl― fertilization on potato plant development. As potato is inefficient in the use of water, we aimed to test if it is possible to improve the hydration status of potato without reducing tuber yield and dry matter by means of Cl― fertilization. We conducted a pot experiment with four different Cl― doses and investigated soil–plant water relations, biomass, tuber yield and dry matter development. Our findings deliver an indication that the potato crop is much less sensitive to Cl― than previously assumed and, more importantly, that a Cl― supply can indeed improve the potato shoot water status. This happened without impairing tuber yield and dry matter. Since potato is very sensitive to drought stress, we assume that Cl― fertilization is a promising measure to improve the drought resilience of potato
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
- …
