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Background and aims: The ever-increasing demand of fresh water from irrigated agriculture and the water scarcity condition that characterizes the Mediterranean region, encourages the adoption of efficient water saving strategies. In this study, the electrical resistivity imaging (ERI) technique was applied for characterizing the mass exchange mechanisms affecting the continuous soil-plant system of heterogeneous micro-irrigated orchards. Methods: Time-lapse ERI surveys were carried out in a multi-variety and mixed-age orange orchard located in Eastern Sicily (insular Italy). The time-lapse ERI monitoring was coupled with the use of independent soil water content (SWC) measurements. Results and conclusions: A clear relationship between the soil electrical resistivity (ER) and the measured SWC changes was identified in the soil under the mixed-age orchard (with an overall coefficient of determination value of 0.63). Specifically, this study highlights the dependency of SWC dynamics as function of tree age. Overall, an increase in ER was obtained in correspondence to the soil domain where the younger trees were located (< = 3 years). This behaviour was inferred to result from the higher soil evaporation process active at these locations, due to less vegetation cover of the younger trees and, consequently to their lesser root extension in comparison to the mature trees (> = 8 years). On the other hand, in mature trees, characterized by denser root biomass, there were more evident decreasing patterns of ER (i.e., greater changes in SWC), due to greater transpiration rates that caused lower initial SWC under these conditions in comparison to the younger trees. [ABSTRACT FROM AUTHOR]

In Italy, the restrictive approach for treated wastewater reuse in agriculture has led to some difficulties in promoting this practice. In order to assess the health risk associated with the use of wastewater in agriculture, an experiment was conducted in an open field near the constructed wetland (CW) system of San Michele di Ganzaria (Eastern Sicily), during the irrigation seasons 2004-2009. In particular the impact on tomato crops of drip and sub-drip irrigation with treated municipal wastewater, as well as effects of wastewater reuse on the irrigation system, main production features, hydrological soil behaviour, and microbial soil and products contamination were investigated. Notwithstanding the fact that globally CW effluents did not match microbiological standards for wastewater reuse of Italian legislation, the median infection risk (function of the recommended tolerable additional disease burden of 10-6 DALY (disability-adjusted life year) loss per person per year) suggested by the 2006 World Health Organization Guidelines for rotavirus, Campylobacter and Ctyptosporidium for lettuce irrigation under unrestricted irrigation scenario was achieved. [ABSTRACT FROM AUTHOR]

The effect of four different irrigation levels on the marketable yield and economic return of summer-growth lettuce was evaluated during 2005 and 2006 in Eastern Sicily, Italy. The viability of deficit irrigation was evaluated by estimating optimum applied water levels. Actual evapotranspiration (ETa) was estimated by combining pan evaporation measures and the Penman–Monteith approach (ET0-PM). The highest marketable yield of lettuce was recorded for plots receiving 100% ET0-PM. For deficit irrigated plots, reductions in crop production were ascribed to a decrease in lettuce weight. Crop coefficients equal to 1 determined maximum crop production values. Crop water use efficiency was maximum at a 100% ET0-PM level of water applied, corresponding to yield of 0.3 t ha-1 mm-1. Irrigation water use efficiency reached its maximum at a 40% ET0-PM level, with values of 0.54 and 0.44 t ha-1 mm-1 during 2005 and 2006, respectively. Water applied and marketable yield of lettuce showed a significant quadratic relationship. Cost functions had a quadratic form during 2005 and a linear form during 2006. In the land-limiting condition the optimal economic levels fit the agronomic ones well. In the water-limiting condition, ranges of water deficit of 15–44% and 74–94% were as profitable as full irrigation, thus contributing to appreciable water savings. [ABSTRACT FROM AUTHOR]

Abstract: Satellite remote sensed data on canopy biophysical properties, ground data and agro-meteorological information were combined to estimate evapotranspiration (ET) fluxes of orange orchards using a modified Penman–Monteith equation. The study was carried out during the irrigation season 2004 in an irrigation district, cover for about 95% with orange groves, of 1550ha located in eastern Sicily (Italy). The spatial pattern in ET-fluxes have been analysed using IKONOS high-resolution satellite and hyper-spectral ground data acquired and processed for the study-area. The remote estimates of ET-fluxes varied between 1.3 and 5.7mm/day, with a daily average value of about 4.2mm, showing a good agreement with crop ET values determined as residual of soil water balance of selected ground control sites. Crop coefficient estimates ranged between 0.22 and 1.08 showing positive correlations with percentages of ground cover (C g) increasing from 30 to 80% ground shading and with LAI values. By comparing ET estimates with water volumes supplied in each sub-district of the study-area, the performance indicator “IP” was evaluated, allowing to rank the conditions of un-fulfilment of crop water requirements by public and private water distribution systems. Generally, out of 29 sub-districts, 14 had “IP” values less than 50%, revealing a sub-optimal water supply for the study-area. [Copyright &y& Elsevier]

An integrated Rough Set approach is proposed and implemented to discover the historical operating rules of a Sicilian irrigation purpose reservoir. Operating rules are derived by expressing monthly releases from the reservoir as functions of stored volume, inflow and release during a 35-years period. This is accomplished through the Rough Set approach as implemented in the Rose package and the use of some indices able to recognize and further screen out the effective rules used in water supply reservoir management. This approach represents a new mathematical tool quite different to classical fuzzy rule-based systems in the decision rules induction. Results show that the integrated Rough Set approach allows to individuate with acceptable reliability the real criteria used for the system management. [ABSTRACT FROM AUTHOR]