Italian networking of public experimental sites working on Organic Farming: an experience of networking in research

Research in organic farming, especially with an agro-ecological approach, is strictly linked to local conditions and interactions among several variables. The paper will present an example of a process developed in the Italian context to integrate and harmonize research in organic farming from different research stations, with different local conditions. Collecting similar and comparable data from different research stations participating in the network can have an interesting impact in results of organic farming experiments, due to high number and variability of data. ARSIA Toscana, with the aim of creating an Italian National Network of public experimental stations working in organic farming, involved FIRAB as a facilitator of the participatory process. The proposed process follows two parallel paths: individual questionnaire to single experimental sites to know the specific activities in place on organic farming and a series of meetings with direct involvement and exchange among researchers and policy makers from different regions to comment results of the questionnaire and future development of organic research in public experimental stations. The main outcome of the process has been the choice of a specific transversal topic to build the network: the development of synthetic agro-environmental indicators

Effect of homegarden and parkland agroforestry practices in Ethiopia on selected soil properties

Ethiopian agricultural lands are fragile due to inherent unfavourable soil properties, over-exploitation, mismanagement (deforestation, over-grazing and inappropriate land use systems) and harsh weather conditions. These factors are worsened by changing climatic conditions, leading to significant problems in terms of soil erosion and loss of soil fertility. The consequences of such processes can be detected at the economic (agricultural production is currently being jeopardized) and biological (risks of biodiversity loss and habitat fragmentation) levels. However, the use of tree/shrub species in various agroforestry practices can increase soil nutrient supply through nitrogen fixation, improve soil structure, reduce soil erosion and nutrient losses. A study was carried out in the Amhara region, Ethiopia to evaluate the effect of homegarden and parkland agroforestry practices on selected soil chemical properties. Soil samples were taken from 20x20m square plots established in homegarden agroforestry and adjacent agricultural land without trees (control). In parkland agroforestry practice, two dominant tree species in each of the five villages were chosen. Soil samples were taken from the tree at the midpoint of the canopy projection, at 0-15 and 15-30 cm depths. The collected soil samples were air-dried, homogenized and passed through a 2 mm sieve for subsequent soil chemical analysis. The results indicated that all soil chemical properties except total nitrogen were significantly (P ≤ 0.05) affected by the agroforestry practices. Higher soil organic carbon, organic matter, available phosphorus, and exchangeable potassium were found in the homegarden agroforestry practice, while the lowest values were recorded in without-tree fields (control). All soil chemical properties except soil pH decreased as the soil depth increased. Higher value of organic carbon, available phosphorus, and exchangeable potassium were found in the homegarden agroforestry likely because of a higher proportion of deep-rooted tree/shrub species and species belonging to the legume functional group. Therefore, the homegarden agroforestry practice can be used as an ecologically friendly and sustainable alternative to maintaining soil fertility

Health Hazard From Endogenous Gas Emissions In Alban Hills (Rome, Italy)

The quiescent volcano of Alban Hills, near Rome, is characterized by strong emission of endogenous gas (mostly CO2 with minor H2S) from zones where excavation removed the superficial impervious cover. These gases –denser than air- accumulate in morphological depressions and many lethal accidents to animals and also to one person have occurred in the last years. At Cava dei Selci and Solforata sites, the CO2 flux has been estimated to 95 and 200 tons/day respectively from 0,6 and 5 hectares. Dangerous accidental gas blowouts also occurred from boreholes that reached gas pressurized shallow aquifers. In order to evaluate the gas hazard, several geochemical surveys were performed to estimate the CO2 and H2S soil flux and air concentration. In the urbanized area of Vigna Fiorita, dangerous indoor conditions were found with [CO2] up to 10 % and [H2S] up to 30 ppm and lethal indoor [CO2] (up to 22%) persisted within a non-ventilated house. Results will help in suggesting appropriate prevention measures to be adopted by residents. An important discovery was found measuring CO2 and H2S air concentration (by TDL at 30 cm from the ground). In periods of very low or no wind (generally in night-time) lethal concentrations were reached by H2S (up to 400 ppm), whereas [CO2] remained at tolerable values. These data indicate that the many animal deaths occurred in these years and previously attributed to CO2 where instead caused by H2S and a specific study on the health effects of this gas on man and on different animal species is presently under progress. Alban Hills test site provides useful methodological indications on how to assess the insidious hazard associated to soil gas release in inhabited zones of quiescent or recent volcanoes

Seismic location improvements from an OBS/H temporary network in Southern Tyrrhenian Sea

We present the first investigation performed on the seismicity of Southern Tyrrhenian Sea, off-shore Sicily with the contribution of data from broad-band ocean bottom seismometers and hydrophones (OBS/H). Offshore data were recorded during the TYrrhenian Deep sea Experiment (TYDE) from December 2000 to May 2001 in the Southern Tyrrhenian Sea. Hypocenter locations of a cluster of 53 seismic events occurred in March 2001 in north-eastern Sicily were estimated by the integration of land (permanent network) and offshore (temporary network) data and compared with locations estimated from land data only. The scatter of the cluster was evaluated by dispersion parameters. The off-shore data significantly reduced the scatter of the swarm hypocenters also restricting the depth range of the cluster. Moreover, space trends of the event distribution originally shown by the land data were only partially confirmed by the land-sea joint data. In order to assess the efficiency in terms of hypocenter mislocations in the subject area, of a land-sea integrated network with respect to a land-based network, we performed simulations by assuming a grid distribution of earthquakes and a recent local 3D velocity model, computing synthetic arrival times of body waves to the stations of both network configurations (integrated and land-based) perturbing the computed times and relocating earthquakes by inversion. The results of the synthetic tests demonstrated that the presence of sea bottom stations in the Tyrrhenian basin can reduce the mislocations of large magnitude and/or superficial earthquakes in the southernmost Calabria and Messina Strait and of low magnitude and/or deep earthquakes in north-eastern Sicily. The major accuracy of synthetic earthquake locations obtained including OBS/H data provides an additional support to the interpretation of the cluster occurred in March 2001 and to the opportunity of long-term installation of an off-shore network like TYDE in the study region

Wide band gap materials as a new tuning strategy for dye doped cholesteric liquid crystals laser

A new tuning strategy for mirror-less liquid crystals laser is presented. A three layer cell is prepared with two cholesteric layers sandwiching a layer containing an isotropic mixture of a photoluminescent dye. One of the chiral layers contains a wide band gap material while the second layer consists of a series of small band gap materials. Through the combination of these two layers, a set of mirrors that can selectively reflect different wavelengths is obtained. A different laser wavelength is emitted from different regions of the cell under the pumping beam irradiation. (C) 2009 Optical Society of Americ

Receiver Function Analysis at Stromboli Volcano (Italy)

This study focuses on constraining the crust and upper mantle discontinuities at Stromboli volcano by applying the receiver function (RF) analysis. This technique utilizes the waveforms of P-SV conversions generated by discontinuities to infer the structure beneath the seismic stations. RFs have been obtained by deconvolving the vertical component of teleseismic P-wave records from the corresponding rotate horizontal components applying the Multi-Taper Spectral Correlation technique. For this study the seismograms of about 125 teleseismic earthquakes (M greater than 6.0), recorded between 2004 and 2006 at 13 broad-band seismic stations deployed by the INGV, have been considered. A preliminar characterization of the structure beneath the stations has been inferred from the stacking of teleseismic Ps converted waves and multiply converted waves at the seismic interface. The analysis, at frequency of 1 and 2 Hz, show a horizontal seismic discontinuity at an average depth of about 17 km and a Vp/Vs ratio lower than 1.73. This discontinuity explains the positive pulses about 1.9 s and 7.5 s after the direct P arrival. These pulses can be interpreted as Ps and PpPs converted phases, respectively. The depth of this discontinuity is in agreement with the Moho-depth obtained in independent studies