1,721,124 research outputs found
Influenza dell'irradianza e dell'azoto sul contenuto di azoto e anioni inorganici nella rucola (Eruca sativa Miller)
No full textImpiego dell'infiltrometro a tensione: determinazione della conducibilità idraulica e stima della porosità del suolo
No full textAzoto, temperatura, irradianza e contenuto dei principali anioni e cationi in foglie di cima di rapa
No full textComparing physical quality of tilled and no-tilled soils in an almondorchard in southern Italy
No full textNo-tillage (NT) is an alternative way of reducing costs and lessening the burden of working the land, but in essence it is a method of sustainable land use in dryland cropping systems. The physical quality of the soil is the fundamental factor that defines the sustainability of agro-ecosystems, and its evaluation can be obtained using both capacitive and dynamic indicators. The main objectives of this study were: i) to assess the physical quality of the soil in an almond orchard where long-term different soil tillage systems and weed control methods, such as NT with chemical control and surface tillage (ST), were used; and ii) to compare the indicators under consideration with the proposed reference values, using the information gathered to evaluate the effects of NT and ST. The following physical properties were determined: bulk density, air capacity, macroporosity, plant available water capacity, relative field capacity, Dexter’s index, field saturated hydraulic conductivity, as well as the location (modal, median, and mean pore diameter) and shape (standard deviation, skewness, and kurtosis) parameters which corresponded to the equivalent pore size distribution functions. Our results showed that the physical soil indicators adopted were sufficiently sensitive to identify tillage-induced changes and then to quantify the physical quality of rigid to moderately expansive agricultural soils. After thirty years of NT, a set of capacitive indicators, along with measurements of hydraulic conductivity, used in conjunction with an optimal pore volume distribution and the water release curve, unanimously classified the quality of the studied soil as optimal or near optimal
Variability of soil hydraulic conductivity and Gardner's alpha for different soils of south Italy
No full textTemporal changes of soil physical quality under two residue management systems
No full textAlthough crop residue management is known to affect near-surface soil physical quality, little is known about the temporal variability of these indicators over short time intervals. This study evaluates the temporal changes of nine indicators of soil physical quality. These are organic carbon content, structural stability index, bulk density, macroporosity, air capacity, relative field capacity, plant available water capacity, Dexter’s S-index and saturated hydraulic conductivity. A second set of soil physical indicators, based on the distribution of soil pore volume, was also evaluated. The indicators were determined in three different times during the growing cycle of winter durum wheat cultivated within a long-term field research carrying out in Southern Italy and comparing two types of
crop residue management, that is, burning (B) and soil incorporation (I). Only the bulk density changed over time for both treatments, although the air capacity also changed for the incorporation of wheat residues. Residual effects of the autumnal soil tillage and soil compaction were a common source of variability, irrespective of which treatment was used. Based on the existing guidelines for evaluating the physical quality of these agricultural soils, optimal or near-optimal values were detected in about half of the cases under consideration. This suggests that both B and I create sufficiently good conditions for crop growth during the crop cycle. The comparison between observed and optimal soil pore distribution function was always poor. The pore volume distributions howed lower densities of small pores and relatively higher densities of large pores than the proposed optimal distribution. This study also suggests that the considered optimal or references curves probably cannot be applied successfully to a wide range of agricultural soils
The water deficit and aridity indexes in the Capitanata plain calculated by statistical downscaling
No full textThis work describes the results obtained by the statistical downscaling
technique for the assessment of changes in precipitation (P),
potential evaporation (PE). In turn P and PE are used for computing
two indexes of water availability, namely the index of water deficit
(WDI) and the aridity index (AI). The analysis is carried out for the
Capitanata plain (South-East of Italy) and the A2 scenario of the IPCC
Assessment Report 4 (AR4). The large-scale temperature at the
1000hPa level and sea level pressure fields are used as predictors. The
local precipitation and potential evaporation time series are used as
predictands. The statistical downscaling technique used is based on
Canonical Correlation Analysis. A validation procedure of the model is
performed and the same technique is used for climatic projections of
P, PE and consequently WDI and AI. Climate analysis and projections at
this local space scale is an important issue not only for current water
management and planning, but also for improving the irrigation efficiency
considering future climate change scenarios
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
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