1,720,961 research outputs found
Evaluation of almond shells as cover material and minor component of substrates for young plants
No full textAlmond trees are grown in southern Italy, mainly in Sicily and Apulia. It is estimated that every year no less than 100,000 m3 of almond shells (AS), the ligneous material forming the thick endocarp or husk of almond fruit, incur as byproduct which is mainly used for domestic or greenhouse heating. Sometimes almond shells are used in mixtures with other organic materials to prepare green compost. This study investigates the physical and chemical features of crushed AS and their behavior when used in vegetable nurseries. High air content, low shrinkage, low water retention, moderate swelling capacity, low EC, sub-acid pH and an appreciable lignin content are some of the observed peculiarities. Trials were carried out using a granulometry fraction of 1-2 mm, in order to evaluate the suitability as cover material for plugs, and as minor component (5% v/v) in substrates for vegetable seedlings. Data from cultivation trials showed encouraging results when AS were used as covering material. In comparison with vermiculite, AS influenced foliage growth in many cases reducing plant height, improving seedling compactness, dry matter and final quality. Moreover, an improvement in seedling quality was observed when AS were added to peat based substrates. Likewise, when used as a cover material, seedlings look more compact, and showed a higher dry matter and chlorophyll content compared to the control
Effects of two nitrogen enriched biochars on barley grown on peat : preliminary observations
No full textThe ability of biochar to sorb ammonium is well known, with different mechanisms being postulated. In this study the possibility to use ammonium loaded biochars in growing media, in comparison to other sorbents like natural zeolites was exploited. A spruce biochar and a poplar biochar, obtained by high temperature pyro-gasification, and a natural zeolite (chabazite) were loaded with ammonium by soaking in 0.5M ammonium sulphate. An incubation test and a plant growth trial were performed on the ammonium-enriched materials added to a peat based growing media, compared with (NH4)2SO4. The peat was able to quickly retain the ammonium added with both mineral fertiliser and biochars. The loaded biochars do not act as slow release N carriers; nevertheless, they promote plant nitrogen uptake. The zeolite strongly retained ammonium throughout the experiment leaving an amount of soluble nitrogen lower than plant requirements
Ammonium nutrition as a strategy for cadmium mobilisation in the rhizosphere of sunflower
No full textAmmonium nutrition of higher plants results in rhizosphere acidification due to proton excretion by root
cells. The acidification induced by ammonium-fed plants can be exploited to promote a localised metal
mobilisation in neutral to alkaline polluted soils and therefore to improve phytoextraction. The effects of
ammonium uptake by sunflower (Helianthus annuus L.) plants on the external medium pH, aerial and root
growth and tolerance to soluble Cd were studied in hydroponic culture. The ammonium-fed sunflowers
induced a strong acidification of the solution and, compared to the nitrate-fed sunflowers, a small modification
in mineral nutrition and a different Cd partitioning between root and shoot. Moreover, ammonium
nutrition was found to induce a great mobilisation of a sparingly soluble form of cadmium (CdCO3). A pot
experiment studied the ability of different ammonium-based fertilisers (ammonium sulphate, ammonium
thiosulphate, urea) to modify bulk and rhizo-soil pH, compared to the effect of calcium nitrate and to the
unfertilised soil. Furthermore, in order to promote the persistence of ammonium in soil, a combined
treatment of ammonium sulphate and DMPP, a nitrification inhibitor, was tested. Soil pH was strongly
modified by chemical and biological processes involved in fertiliser transformations. In particular, due to
nitrification, all ammonium-based treatments showed a bulk soil acidification of over 1.5 pH units and a
relative increase in rhizo-soil pH as a consequence of nitrate uptake. The treatment with DMPP showed an
opposite trend with a lower pH in rhizo-soil than in bulk soil. The ability of ammonium-fed plants to
mobilise heavy metals from the non-labile pool was studied in another pot experiment using three soils with
different properties and at different degree and type of heavy metal contamination. Whatever the soil, the
metal concentrations in shoots were higher in plants fed with ammonium (ammonium sulphate plus DMPP
treatment). Our results support the hypothesis that ammonium nutrition with nitrification inhibitors is a
viable strategy to improve heavy metals phytoextraction while protecting bulk soil from acidification and
presumably from metal leaching
Impact of glucose on microbial community of a soil containing pyrite cinders : role of bacteria in arsenic mobilization under submerged condition
No full textArsenic transformation and mobilization in a pyrite cinder-polluted soil were studied under submerged conditions both in the presence and absence of glucose. The presence of the carbon source enhanced bacterial activity and a reduction in the redox potential, resulting in release of higher amounts of arsenic iron and manganese in the aqueous phase. Since arsenic solubilization was not concomitant to that of iron, desorption rather than dissolution was found to be the main mechanism controlling its release from pyrite cinders. Arsenate was reduced to arsenite whose presence increased during the time course of the experiment. Denaturing gradient gel electrophoresis analysis of 16S rRNA genes of the total bacterial community revealed that the addition of glucose stimulated uncultivable populations of Flavobacterium and Paenibacillus. The isolation technique enabled the characterisation of nineteen arsenic-resistant bacteria, mostly related to the facultative aerobic genera Bacillus, Paenibacillus, Staphylococcus and to Rhodococcus and Micromonospora. Most of them contained putative arsenate reductase and/or arsenite efflux pump as indicated by the presence of ArsC and/or ArsB genes. Four strains showed the ability to reduce arsenate by an intracellular detoxification mechanism, and one strain was able to oxidize arsenite, indicating that bacteria with the ability to oxidize or reduce arsenic are ubiquitous in soils. The findings confirm that bacterial activity was responsible for the arsenic reduction causing the solubilization of the metalloid from pyrite cinders to aqueous phases. Reducing conditions, such as those present in flooded soils in the presence of readily utilizable carbon sources could induce arsenic mobilization
Changes in volume (quantity) by mixing components : trials on a small-scale and on a full-scale (factory)
No full textAddition of minerals to organic components often cause changes in the final volume of a growing medium (increases or more frequently decreases), especially in case of mixing components with particles of different sizes and bulk densities. An experimental study was conducted, comprised of a small-scale trial in laboratory and a full-scale trial in five growing media companies. In the lab trial two mixtures (peat/pumice and peat/compost in different ratios) were prepared in a concrete mixer, and measured and theoretical volumes (EN 12580) were compared. In the full-scale, changes in volumes of an expected 80:20 vol:vol mixture of peat and pumice were studied after blending and packaging. In the lab, trial mixture volumes decreased linearly with increasing doses of pumice (up to 15% of reduction); on the contrary compost had a minimal effect on the final volumes. Reductions in volume were observed also in the full-scale trial, especially after packaging and the extent could be related with the highest dosages of pumice and with the addition of water during processing. During bags storage on pallets further drops of volume were noticed. The small-scale procedure can be predictive of the reduction of volume of the binary mixtures tested in plants
Applicabilità della spettroscopia NIR per la caratterizzazione analitica delle torbe
No full textIn questo lavoro si riportano i risultati dell’applicazione della spettroscopia NIR per la determinazione di caratteristiche chimiche e fisiche di torbe impiegate nella costituzione di substrati colturali. Su 64 campioni di torbe raccolti presso tre produttori di substrati sono state effettuate le principali determinazioni analitiche (pH, conducibilità, carbonio e azoto totali, fibre: neutro-deterse, acido-deterse, lignina acido-detersa, acqua facilmente disponibile, densità apparente e porosità totale) e sono stati acquisiti i relativi spettri NIR. Dati analitici e dati spettroscopici sono stati correlati attraverso regressione PLS (Partial Least Square) per ottenere i modelli di calibrazione relativi ai singoli parametri. Le calibrazioni relative a C e N totali, NDF, ADL, porosità e densità apparente possono essere considerate soddisfacenti, mentre per i restanti parametri necessitano di essere meglio sviluppate
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
First investigation on nematofauna in well rotted manure
No full textBeneficial effects of manure on soil and crop yield have been largely demonstrated, because of its high organic matter content. Moreover, manure increased biological activity and diversity of soil microorganisms, which in turn can lead to minimize crop damage from soil borne pathogens. Reports on the success of application of manure in order to reduce root lesion nematodes in different crop systems are numerous.
Moreover it is largely showed that the addiction of manure into soil lead to a gradual increase of opportunistic nematodes in response to an increase in microbial activity.
However, there are few studies on characterization of nematode communities on well rotted cow manure and the majority of the studies are focused on vertebrates parasitic nematodes. We thus decided to study the nematode community of manure, excluding vertebrates parasitic nematodes, in order to give further information about the effect of the manure on nematode communities. Samples were collected from a well rotted cow manure used in a field trial.
The mean number of nematodes/100 g of manure was 305. Only 5 genera were recorded, belonging to 3 families. Because of manure composition, only enriched-oportunistis and saprophytic nematodes were found. In fact, omnivores/saprophytic nematodes were the dominant trophic group (51.9%), and bacterial feeders nematodes were subdominant (47.8%). Fungal feeders were recorded in a very low percentage (0.3%) and plant feeders were not detected. The majority of bacterial feeders belonged to Rhabditidae, and Diplogasteridae was dominant between omnivores/saprophytic. The most abundant genera recorded was Diplogasteroides; on the contrary, Butlerius had the lowest percentage (0.1%). The genera composition was extremely reduced and therefore the biodiversity was low as confirmed by MI (1.00) and H’ (0.38).
The data suggest that manure could affect nematofauna not only improving bacterial activity but also introducing nematode genera. That could have effects on the nematofauna biodiversity and soil quality and it could be strategic in managing soil extremely compromized or depleted. Further studies are necessary to assess the ability of nematodes from the manure to fit into new soil ecosystem
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
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