The island of Sicily has a long standing tradition in citrus growing. We evaluated the sustainability of orange and lemon orchards, under organic and conventional farming, using an energy, environmental and economic analysis of the whole production cycle by using a life cycle assessment approach. These orchard systems differ only in terms of a few of the inputs used and the duration of the various agricultural operations. The quantity of energy consumption in the production cycle was calculated by multiplying the quantity of inputs used by the energy conversion factors drawn from the literature. The production costs were calculated considering all internal costs, including equipment, materials, wages, and costs of working capital. The performance of the two systems (organic and conventional), was compared over a period of fifty years. The results, based on unit surface area (ha) production, prove the stronger sustainability of the organic over the conventional system, both in terms of energy consumption and environmental impact, especially for lemons. The sustainability of organic systems is mainly due to the use of environmentally friendly crop inputs (fertilizers, not use of synthetic products, etc.). In terms of production costs, the conventional management systems were more expensive, and both systems were heavily influenced by wages. In terms of kg of final product, the organic production system showed better environmental and energy performances.

the first month of the season, when the water management between these two practices was different, indicated that K c and water use were lower in DS systems relative to WS systems when there was only one irrigation flush during this period, while two or three irrigation flushes resulted in similar values between the two systems.

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A micrometeorological approach based on the surface energy balance was adopted to estimate evapotranspiration fluxes and crop coefficient data from an irrigated cactus pear [Opuntia ficus-indica L. (Mill.)] orchard under Mediterranean climatic conditions. Highfrequency temperature readings were taken above the canopy top to get sensible heat flux values (H SR) using the surface renewal technique. These values were compared against eddy covariance sensible heat fluxes (H EC) for calibration. Latent heat flux (or evapotranspiration, ET) was obtained by solving the daily energy balance equation. Measurements of soil hydraulic components were integrated with the analysis of the surface energy fluxes and crop development in terms of phenology and aboveground biomass accumulation. Microlysimeters were used to compute evaporation rates, allowing the separation of daily transpiration from ET data. Ecophysiological measurements were carried to estimate dry weight accumulation and partitioning. Cactus pear evapotranspired a total of approximately 286 and 252 mm of water during the two monitored growing seasons, respectively. Average daily values of crop (ET c) and reference (ET 0) evapotranspiration were in the order of 2.5 and 5.0 mm, respectively, with a corresponding value of the mean crop coefficient of approximately 0.40. The annual dry mass fixed per single tree was 38.8 AE 1.3 kg, with a total production of 12.9 t ha −1 , which is comparable to many C 3 and C 4 plants and resulted in a water use efficiency (WUE) of 4.6 and 4.4 g DM kg H 2 O −1 in 2009 and 2010, respectively. The stem area index (SAI) was 3.5.

Orange (Citrus sinensis L.) is one of the main fruit crops worldwide and its evergreen orchards may have a great potential for carbon (C) sequestration, but no data are currently available. In order to understand carbon fluxes in orange orchards, an experiment was undertaken on traditional and\ud intensive planting systems.\ud The experiment used C. sinensis scions grafted onto Citrus aurantium (bitter orange) rootstock. One orchard contained 14-year-old trees of the cv. Tarocco Scire` (a blood orange) grown in a traditional system with 494 trees/ha. The second orchard contained 12-year-old trees of the cv. Newhall (a\ud seedless navel orange) grown in an intensive system with 1000 trees/ha. Net primary productivity(NPP) was obtained by measuring the annual canopy growth of single orange trees and the above ground dry biomass of the ground cover; soil respiration seasonal pattern was measured with an infrared gas analyser (EGM-4, PP System) from June 2005 to May 2006, every 2 weeks from 12.00 noon to 15.00 h for maximum respiration and from 02.00 to 05.00 h for minimum respiration; a 24 h cycle measurement of soil respiration was made every 3 months.\ud Carbon fixation in the fruits and in the canopy of single trees was almost twice as much (10.7 kgC/tree) in the traditional than in the intensive system (5.5 kg C/tree); however, total NPP of the orchard did not change with planting density, being 5.3 t C/ha/year in the traditional system and 5.5 t C/ha/year in the intensive one. Carbon fixation by the ground cover was higher in the traditional (1.1 t C/ha/year) than in the intensive system (0.5 t C/ha/year). Annual soil respiration was 5.9 t C/ha/year in\ud the traditional system and 4.2 t C/ha/year in the intensive one. The carbon balance was almost four times higher in the intensive system (1.8 t C/ha/year) than in the traditional one (0.5 t C/ha/year), due\ud to large differences in soil respiration