1,721,013 research outputs found
Soil quality indicators as influenced by no-till, conventional tillage and nitrogen fertilization after 3 years of continuous barley in the Po valley (Italy)
No full textLa scelta varietale per l'erba medica in collina
No full textLa sperimentazione collegiale condotta in due ambienti dell’Appennino reggiano, in Oltrepò Pavese e sui fianchi della Valsugana, dimostra l’importanza di una appropriata scelta varietale anche per le zone collinari al fine di ottenere un medicaio produttivo e longev
The influence of no-till, conventional tillage and nitrogen fertilization on physico-chemical and biological indicators after three years of monoculture barley
Full text linkAn experimental trial was carried out over three years at Cavacurta (Po valley, Italy) on continuous barley. The soil was a coarse-loamy over sandy, mixed, mesic Fluventic Ustochrept. The experimental design was a split-plot with four replicates; the main factor was the soil management system (conventional tillage, CT, and no-tillage, NT), while the secondary factor was the nitrogen fertilization (N0 = 0, N1 = 50 and N2 = 90 kg N ha-1 year-1). At the end of the third year soil samples were taken in all plots at four depths (0-5, 5-10, 10-15 and 15-20 cm). For these samples, pH, organic matter, total N, available P and cation exchange capacity were determined. On the contrary, water aggregate stability was determined for a single layer (0-20 cm depth), excluding the N1 level of fertilization. The biological indicator, QBS-ar index, was studied only in the layer 0-10 cm. Statistical analysis shows that no-till positively
influenced all the indices except for CEC and QBS-ar. N fertilization had significant effects on CEC only; in the
upper layer, the value in N2 subplots was of approx. 1 cmol+ kg-1 higher than in N0 and N1 subplots. There was no
significant interaction for any of the indices. As regards only the 0-20 cm layer, the most important results are as
follows. The organic matter content in NT plots was significantly higher than in CT plots (32.6 vs 29.8 g kg-1), as
was the total N (2.11 vs 1.97 g kg-1). No-till also had a very clear effect on the Olsen-P (12.3 vs 9.3 mg kg-1). The
most remarkable result was found for the water aggregate stability: for NT plots the value was 246% higher than
for CT plots (34.3 vs 9.9%). As regards the microarthropod community, the value of the QBS-ar index was between 90 and 126, a typical range for soil under barley
Driving crop yield, soil organic C pools, and soil biodiversity with selected winter cover crops under no-till
No full textNo-till (NT) and cover crops (CCs) have been repeatedly recommended for building-up resilience of agro-ecosystems, enhancing soil biodiversity, and steering efficient nutrients cycling and yield. Yet, the overall impact of CCs on soil properties and dynamics during transition may highly change depending on CC species and interactions with field condition. In the present 3-yr field study, we (i) examined how selected CCs (i.e. rye [Secale cereale L.]; phacelia [Phacelia tanacetifolia Benth.] + white mustard [Sinapis alba L.]; Italian ryegrass [Lolium multiflorum Lam.] + crimson clover [Trifolium incarnatum L.] + Persian clover [Trifolium resupinatum L.]; hairy vetch [Vicia villosa Roth] + crimson clover) affect yield performance in a crop sequence of maize (Zea mays L.), soybean (Glycine max L. Merr.), and maize under NT, and (ii) assessed the effects of CCs on inputs to the soil (i.e. biomass, carbon [C], and nitrogen [N]), soil organic C (SOC) and pools, as well as microarthropods and earthworms abundance and diversity. Grain yield during the initial 2-yr period was on average reduced with CCs by 1–23% in maize, and 1–33% in soybean. This effect was less evident with CC residues having low C:N ratio (< 20; i.e. hairy vetch + crimson clover) and erect habitus after termination (i.e. rye). Thereafter, CCs had no effect on maize yield the third year. Soil organic C and pools indicated that (i) the effect of our CC treatments over a 3-yr application is limited to the topmost 5 cm of soil, and (ii) the biomass input with CC residue and its C:N ratio are crucial for boosting soil C cycling. This was also the case for earthworm-related indicators, while arthropods mainly responded to different CCs in terms of evenness. Yet, our results on soil fauna showed that different groups or species need different time for showing effects, thus suggesting that responses may be fully effective in a >3-yr term. We concluded that CC mixtures that allow the best compromise between the high amount of residue and the low residue C:N ratio should be preferred for: (i) reducing possible detrimental effects on grain yield of maize and soybean, and (ii) enhancing soil C cycling and biodiversity. Therefore, selecting appropriate CC species in mixtures represents the main challenge at the field level for pursuing both objectives in the shortest timeframe. Within all options in summer crop sequences, here we reported that mixtures including leguminous cover crops might be primarily considered
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
Slug monitoring and impacts on the ground beetle community in the frame of sustainable pest control in conventional and conservation agroecosystems
Full text linkIn conservation agriculture, slugs are considered significant pests and their monitoring is a key option in the integrated pest management framework. Together with molluscicide applications, predators such as ground beetles can offer a tool for slug control in the field. Through the evaluation of slug and ground beetle monitoring strategies, this work compared their presence in conventional and conservation agricultural plots. The invasive Deroceras invadens was the dominant slug species to occur in all sampling periods. Among Carabidae, Poecilus cupreus and Pterostichus melas were the most abundant species, and Bembidion spp., Brachinus spp., and Harpalus spp. were also common. Beer-baited pitfall traps, whatever their alcoholic content, caught more slugs and ground beetles than wooden boards used as shelters. Slugs were more abundant in conventional plots than in conservation plots, possibly due to the lower presence of natural enemies such as ground beetles. Despite possible impacts on Carabidae, beer-baited pitfall traps should be considered a useful tool for slug monitoring and for the planning of molluscicide applications. Soil management such as minimum-or no-tillage and the presence of cover crops are important elements influencing both slug and ground beetle presence, possibly playing a key role in the maintenance of natural enemy populations
CO2 sequestration from Italian cultivated land: opportunities, challemnges and risks
No full textManagement of agricultural soils may determine soil carbon emission to the atmosphere (source) or soil carbon sequestration (sink). Conventional agriculture is tillage-based (TA) in industrialised as well as developing countries and relies, as a key procedure for seedbed preparation, on mechanical soil tillage with no organic mulch cover. Generally, it seems to speed up the loss of Soil Organic Matter (SOM), by increasing its mineralization and through soil loss by erosion. In addition, soil tillage is a high energy-consuming operation that uses large amounts of fossil fuel per hectare in mechanised systems. In contrast to tillage-based systems, Conservation Agriculture (CA) is considered to be an agro-ecological approach to resource-conserving agricultural production that requires compliance with three linked practical principles, namely: i) minimum mechanical soil disturbance (with no-till and direct seeding); ii) maintenance of permanent organic soil cover (with crops, cover crops and/or crop residues); and iii) species diversification through crop rotations and associations (involving annual and/or perennial crops including tree and pasture crops) Corsi et al. (2012). CA facilitates good agronomy, such as timely operations, and improves overall land husbandry for rained and irrigated production and is complemented by other good practices, such as the use of quality seeds and integrated pest management (Pisante et al., 2012).There is evidence that, in the medium term, the most effective way for adaptation to climate change is represented by a rational management of the biosphere and in particular of the agricultural sector: by the adoption of specific agricultural practices. Agriculture is potentially able to reduce its emission with minor costs with respect to other activities, to increase carbon sequestration and reduce greenhouse gas emissions. In fact, agricultural activities play a fundamental role in soil carbon sequestration and reduction of emissions, mainly because of the high stock capacity of this element associated with long retention time in the soil. The cultivated land (arable and tree crops) occupy 28% of the Italian territory, for a total of 10.9 million ha which can stock massive reserves of carbon by putting in place agronomic measures and/or agro-ecological infrastructure useful to reduce the amount of CO2 in the atmosphere. The net balance of the two processes on an annual basis can result in positive net flows (emissions) or negative (sequestration). However, the aggregated balance sheet of carbon for agricultural soils is subject to significant uncertainties with estimates that can vary greatly depending on the method and data sources. The average European values, for example, range from losses of -0.17 ± 0.33 Mg C ha-1 y-1 (emissions), when calculated from data in the inventory of agricultural soils (available for 33% of the European cultivated land) to values of accumulation of 0.15 ± 0.15, or loss of -0.08 Mg C ha-1 y-1 when calculated with simulation models. It is estimated that in Italy over the past 70 years, the intensification of agricultural activities has caused a net loss of soil organic carbon by 39% compared to the initial content. The extent of actual SOC sequestration achieved on Italian cultivated land will crucially depend on future policies which could contemplate the inclusion of agriculture in an emissions trading scheme, either as a covered sector, or as an offset provider. It is important to face some research questions mainly aimed at removing this barrier to inclusion of soil carbon in emissions trading. Complementary measures, such as research, development and technology transfer to improve the extension to improve adoption of existing techniques or direct financing to accelerate the adoption of conservation farming systems, should be carried out
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