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Scientia Horticulturae 162 (2013) 380–386

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Scientia Horticulturae

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Alternative management for olive orchards grown in semi-aridenvironments: An energy, economic and environmental analysis

Maria Pergolaa, Mariafara Faviaa, Assunta Maria Palesea,∗, Biagio Perrettib,Cristos Xiloyannisa, Giuseppe Celanoa

a Dipartimento delle Culture Europee e del Mediterraneo: Architettura, Ambiente, Patrimoni Culturali (DiCEM), Università degli Studi della Basilicata, ViaSan Rocco, 3 – 75100 Matera, Italyb Scuola di Scienze Agrarie, Forestali, Alimentari ed Ambientali, Università degli Studi della Basilicata, Viale dell’Ateneo Lucano, 10 – 85100 Potenza, Italy

a r t i c l e i n f o

Article history:Received 6 June 2012Received in revised form 29 July 2013Accepted 21 August 2013

Keywords:Olea europaea L.SustainabilityEnergy analysisLCAEconomic analysisWastewater management

a b s t r a c t

The objective of this study was to test a more productive and sustainable system compared to the tradi-tional approach to manage olive orchards at risk of abandonment placed on hilly and mountainous areasof semi-arid environments. The main sustainable features include the use of treated urban wastewater fordrip irrigation and the exploitation of environmentally friendly techniques aimed to preserve/maintainsoil quality, to increase the atmospheric carbon storage in the soil, to correctly use natural resources.The comparison between the two management systems, sustainable – SS′ and conventional – CS′, wascarried out through an energy, economic and environmental analysis. The data used in this paper referto averages for the period 2001–2008. Energy values were calculated by multiplying the amount of farminputs by the related energy conversion factors. The total input energy per kg of olives was 4.43 and2.80 MJ in the SS and CS, respectively. The economic analysis showed that the gross profit of the SS wasconsiderably higher (6276 D ha−1) than the CS (1517 D ha−1). The environmental analysis was carried outaccording to the Life Cycle Assessment (LCA) methodology using SimaPro7.2 software. Emissions of CO2

eq per kg of olives, in SS were 0.08 kg, while in the conventional olive orchard were equal to 0.11 kg.Under our experimental conditions, although the SS was the most energy-consuming system, its greaterproductivity enabled a more ‘sustainable’ kg of olives to be produced, at least regarding CO2 eq emissions,and it seemed to be a much more effective management model in terms of productivity and profitability.The combined use of various methodologies (LCA, energy and economic analysis) could provide criticalinformation for policy makers and producers and help them in making strategic choices.

© 2013 Elsevier B.V. All rights reserved.

1. Introduction

Traditional olive cultivation systems are typical of hilly andmountainous areas of producing countries in the MediterraneanBasin. Conventional olive orchards are generally grown under rain-fed conditions on low fertile soils often tilled. Furthermore, they arecharacterized by low-density planting and their soils are frequentlyexposed to erosion as the slopes are left without vegetation dur-ing autumn–winter rains. The productivity of such systems is verylow because of the above mentioned reasons. Other limiting fac-tors, such as the old-age and large-size of the olive trees, and thelow inputs of labour and materials, lie behind their low productiv-ity. As a consequence, their agronomical management can be hardlysustained from an economic point of view, particularly because tra-ditional systems are frequently associated with small or very small

∗ Corresponding author. Tel.: +39 0971 205274; fax: +39 0835 1971441.E-mail addresses: assunta.palese@unibas.it, dinapalese@hotmail.it (A.M. Palese).

farms (Duarte et al., 2008). All these factors are leading to the aban-donment of traditional olive orchards with serious consequenceson the socio-economic structure and landscape of local rural areas,and negative effects on the environment at a basin level.

At the same time, olive tree cultivation and the extraction ofolive oil can cause resource consumption and detrimental emis-sions into the air, water and soil, all having a great impact on theenvironment (Salomone and Ioppolo, 2012).

Crop production, food processing and product marketing, allgenerate greenhouse gases (GHGs), contributing to global climatechange, and consume large amounts of conventional water andenergy (Dyer et al., 2010; Pimentel, 1992; WHO, 2006). On the otherhand, developing renewable energy sources; combating desertifi-cation and mitigating the effects of climate change; improving thequality of inland and coastal waters; reducing emissions of green-house gases, all represent EU strategic objectives.

Increasing anthropogenic GHG emissions have been changingthe Earth’s climate (Ruddiman, 2003; IPCC, 2006). As Gan et al.(2011) noted, policy-makers, the general public and farmers are

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concerned about climate change and this is driving the develop-ment and adoption of effective measures to reduce GHG emissionsfrom all sectors.

A growing interest is recorded also in searching for alterna-tive irrigation water resources. Some countries in the world (i.e.Israel, California) use systematically reclaimed urban wastewateras supply option in agriculture to overcome water scarcity issuesassociated with population increase, deterioration of surface waterquality, groundwater depletion and climate change (WHO, 2006;Chen et al., 2012). In addition, the use of wastewater in agriculturecan allow the achievement of two among the Millenium Devel-opment Goals (Goal 1: Eliminate the extreme poverty and hunger;Goal 7: Ensure environmental sustainability) adopted by the UnitedNations General Assembly in 2000 (WHO, 2006). Non-conventionalwater resources represent a challenge for both Mediterraneanand continental Europe, which are equally affected by recurrentseasonal water shortages. Within the last document producedby the European Commission ‘A Blueprint to Safeguard Europe’sWater Resources’ (EC, 2012), it is emphasized the necessity to seri-ously consider the water re-use as a convenient supply option forirrigation and to encourage the application of this practice – whichis not commonly used in European Union – by opportune instru-ment and strategies to be provided by EC in the near future.

Another recent topical subject is the energy use in the agricul-tural sector which depends on the size of the population engaged inagriculture, the amount of arable land, the level of mechanization(Ozkan et al., 2004), the type of fertilizers and pesticides used. AsKaltsas et al. (2007) referred, conventional agricultural productionis characterized by a high input of fossil energy which is directlyconsumed by fuel used on the farm, and indirectly in the manufac-turing of fertilizers, plant protection products, machines, etc. So, anenergy analysis can indicate the ways to decrease energy inputs andincrease energy efficiency. Recently, there has been renewed inter-est in the control of energy consumption according to a sustainableapproach in agriculture, and many studies have been performed todeeply know the food systems and thus identify the weakest stagesof the whole chain (Hendrickson, 1994). At the same time, lowenergy inputs production systems are not well accepted by farm-ers who are interested in economic benefits rather than in energyproductivity (Kaltsas et al., 2007). As a matter of fact, minimizingenergy inputs is necessary but not sufficient to obtain an economicbenefit. Therefore, a combination of economic, environmental andenergy analysis of a production system may be more useful forthe application of the best management strategies (Bowers, 1992;Pimentel, 1992; Pimentel et al., 2005; Reganold et al., 2001).

In the last decade the use of the life cycle assessment (LCA)methodology on food-processing has increased (Clasadonte et al.,2010) in order to identify and pursue sustainable food productionand consumption systems (Salomone and Ioppolo, 2012). A verylarge number of articles have been published, which vary fromstudies that focalise attention on environmental emergencies of thesystem analyzed to studies comparing two or more case studies orgiving an overview of the principal results of different case studiesfrom particular countries. So, many authors have carried out lit-erature reviews on LCA applied to agricultural and food products,as can be seen in Hayashi et al. (2005), Hospido et al. (2010), Royet al. (2009), and Shau and Fet (2008). A summary of specific arti-cles containing LCA studies applied to the olive oil industry can befound in Salomone et al. (2010) and Salomone and Ioppolo (2012).

A sustainable and profitable model to manage traditional oliveorchards aimed to induce olive growers to continue their cultiva-tion and to act as controllers of the surrounding environment wasproposed by Palese et al. (2013). Such sustainable system was testedin a semi-arid marginal area of Southern Italy and provides essen-tially the reuse of urban wastewater by drip irrigation and the useof soil management techniques based on the recycling of polygenic

carbon sources produced within the olive orchard (cover crops,pruning material). By comparing such model with the traditionalone (defined as conventional), Palese et al. (2013) found, undertheir experimental conditions, that the alternative managementwas more socially sustainable and more environmentally friendly,more productive and profitable, able to ensure a constant annualproduction characterized by a superior quality which allowed anannual and significant income to the farmer. In order to eventu-ally confirm or not such findings, a further data analysis of thetwo management systems was performed to assess their energy-consuming patterns and environmental impacts according to theLCA methodology.

2. Materials and methods

2.1. Orchard management systems and data collection

The trial was performed in Ferrandina (Basilicata – SouthernItaly, 40◦29′ N, 16◦28′ E). The site is characterised by a semi-aridclimate with an annual precipitation of around 561 mm (mean1976–2006) and an average annual temperature ranging from 15to 17 ◦C. The experimental field was a mature olive orchard (Oleaeuropaea L. – cv Maiatica), roughly 1.3 ha, planted on a sandy loamclassified as a Haplic Calcisol (FAO, WRB, 1998) and characterized bya low organic carbon content (7.0 ± 3.8 g kg−1 – mean of 0–0.60 mlayer ± standard deviation).

In 2000 the olive orchard was split into two parts and subjectedto different management systems (Table 1). One plot, indicatedas conventional system – CS, was managed according to the tra-ditional horticultural techniques of the area which were: tillageperformed 2–3 times per year, and empirical soil fertilizationperformed without considering the plant needs and their par-titioning along the various phenological phases of the annualvegetative cycle, heavy pruning performed every two years dur-ing the winter after a productive year (a so-called ‘on’ year),pruning residues removed from the field and burned. The otherplot, the sustainable system – SS, was microirrigated with urbantreated wastewater reclaimed according to simplified treatmentschemes which allowed to recover N, P and K and use them asfertilizing substances (Lopez et al., 2006; Palese et al., 2009). Inaddition, the favourable position of the wastewater treatmentplant – upstream the experimental olive orchard – allowed todistribute the reclaimed wastewater by gravity without any pump-ing energy costs. The seasonal volume was equal to 3425 m3 ha−1

year−1 (mean 2000–2008). The soil was not tilled and covered byspontaneous weeds which were mowed at least twice a year. Irri-gated trees were lightly pruned each year. Pruning material wascut and left on the ground as mulch together with crop residues.The fertilization plan was designed each year according to thenutrient balance approach (Palese et al., 2012) which took intoaccount the chemical composition of the treated wastewater, soilnutrients pool, olive tree requirements along the vegetative sea-son, pruning material and crop residues management. Treatedwastewater were able to distribute, on an average, an annualamount of N, P and K equal to 63.0, 3.0 and 58.0 kg ha−1, respec-tively (2000–2008). These amounts together with the nutrientsupply coming from the pruning material recycling, allowed a sig-nificant fertilizer save. Particularly, with respect to N, olive treeneeds were fully satisfied by integrative N fertirrigations (about40.0 kg ha−1 year−1 versus about 120.0 kg ha−1 year−1 as total Nneed for olive trees).

Throughout the considered period, thanks to irrigation and tothe better agriculture practices, SS showed a remarkable shift froman alternate to a yearly production, and an increase in both thequantity and quality of olive production (Table 2) (Palese et al.,

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Table 1Main agronomic features of the two management systems, conventional system (CS) and sustainable system (SS).

CS SSCultivar Maiatica Maiatica

Planting density 156 trees ha−1 (8 m × 8 m) 156 trees ha−1 (8 m × 8 m)Training system Vase trained Vase trainedPruning Manual, heavy, every two years Manual, light, annualPruning residues Removed from the field Cut and left on the ground as a mulchIrrigation – Reclaimed urban wastewaterFertilization Empirical fertilization Annual – guided fertirrigationWeed control Shallow tillage Soil covered by spontaneous weeds mowed at least twice a yearPest and disease control – Regional agricultural extension service protocolHarvesting Semi-mechanized, every two years Semi-mechanized, annualProducts Oil olives and table olives Oil olives and table olives

Table 2Farm inputs and outputs in the two management systems, conventional system (CS) and sustainable system (SS). Yields and percentage distribution between olives for tableand oil-use are also reported. Data are averages from the reference period (2001–2008).

Input CS SS Output CS SS

Total fertilizers (kg ha−1) 75 150 Average 2001–2008Ammonium sulphate 0 110 Yield (kg ha−1) 4210 9733Urea 0 40 Oil olives (%) 52% 7%Ammonium nitrate 75 0 Table olives (%) 48% 93%

Chemicals (kg ha−1) 0 6Pesticides 0 4Copper 0 2

Treated wastewater (m3 ha−1) 0 3425Plastic containera (n◦) 131 302Human labour (h ha−1) 158 363Machinery (h ha−1) 160 343Diesel – oil (kg) 163 628Lubricants (kg) 3 10

aEstimated life span: 15 years.

2013). In particular, 93% of SS products (mean 2001-2008) satisfiedthe quality standard requirements for table olives (Table 2).

Pest and disease control was performed according to theregional service recommendations for commercial olive groves.

Detailed data on farming operations (farm inputs such asamounts and type of fertilizers and chemicals used; type ofmachineries used and time commitment; human labour expressedas number of workers, and hours worked) performed in both sys-tems were systematically collected – year by year from 2001 till2008 – by means of interview to the orchard owner and writtendown in a notebook. At the same way, yields and merceologicalfeatures of olives, and pruning material amounts, were annuallymeasured on a representative number of olive trees.

2.2. Energy analysis

The energy values, expressed as Mega Joule (MJ), were obtainedby multiplying the amounts of labour, machinery and farminputs, by the relative conversion factors taken from the literature(Monarca et al., 2009; Page, 2009; Pimentel and Pimentel, 1979;Volpi, 1992).

The input energy was considered in terms of direct and embod-ied forms. Direct energy is represented by the human labour anddiesel fuel required for olive orchard management, while embodiedenergy, said also indirect energy, refers to the chemicals, fertili-zers, and plastic materials plus the annual use and maintenance ofmachineries (Milà i Canals, 2003; Page, 2009).

2.3. Economic analysis

A detailed description of the economic analysis is reported inPalese et al. (2013).

In summary, the profitability of the two systems was measuredusing the gross profit (GP) per hectare which was calculated as the

difference between the total output (TO), that is the revenue fromsales of oil and table olives, and the production costs (PC), that isthe sum of variable and fixed costs, gross of taxes and overheads.

2.4. Environmental analysis

To quantify the environmental impact of the two studiedsystems, a life cycle analysis was performed using the LCA method-ology, as stated by ISO 14040 series (ISO 14044, 2006a; ISO 14040,2006b).

The aim of this analysis is to evaluate the environmental sus-tainability of the two systems and to identify the agriculturalpractices or inputs which give rise to the most significant envi-ronmental problems.

The system boundary was set at the farm gate, because the maingoal of the study was to compare the two agricultural produc-tion systems. Therefore, the analysis considers only the agriculturalpractices for olive cultivation and the encompassed impact asso-ciated with the construction of machineries and infrastructures;fuel and lubricant; irrigation system; wastewater treatment; plas-tic containers; fertilizers and chemicals used in the various farmingoperations.

Two functional units (1 ha of farm land and 1 kg of olives) werechosen in order to process the inventory data and results, and toimprove the interpretation of the environmental results (Seda et al.,2010).

Detailed data related to the different agricultural phases andthe materials used (machineries, amount of fertilizers, irrigation,soil management, etc.), recorded year by year, were used for theanalyses. Ecoinvent databases were used to assess the impact ofall agricultural operations and all inputs, except those related tothe disinfection treatment of the urban wastewater. In our casestudy, wastewater is treated by a pilot unit according to simpli-fied schemes (Lopez et al., 2006; Palese et al., 2009). Due to the

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Table 3Materials and inputs referred to one hectare.Conventional system (CS) and sustain-able system (SS).

Materials and inputs CS SS

PruningDiesel and lubricants (kg) 3.05 4.06Agricultural machinery (kg) 0.14 0.14

Pruning residues cuttingDiesel and lubricants (kg) 83.39Agricultural machinery (kg) 3.37

Pest and diseases controlDiesel and lubricants (kg) 166.78Agricultural machinery (kg) 7.73Copper (kg) 2Pesticide unspecified (kg) 4

Weed controlDiesel and lubricants (kg) 125Agricultural machinery (kg) 5.05

Soil tillageDiesel and lubricants (kg) 83.34Agricultural machinery (kg) 5.29

IrrigationTreated wastewater (m3) 3425System (polyethylene pipes) (kg) 312

FertilizationDiesel and lubricants (kg) 7.11 41.47Agricultural machinery (kg) 0.29 1.77Ammonium nitrate (kg) 75Ammonium sulphate (kg) 110Urea (kg) 40

HarvestingDiesel and lubricants (kg) 87.29 254Agricultural machinery (kg) 3.22 9.64Plastic containers (kg) 17 40

pilot scale of the treatment plan and to the lack of specific techni-cal data, the impact related to the reclamation of wastewater werecalculated on the basis of data reported by Amores et al. (2013). Inparticular, data used correspond to a tertiary treatment, which con-sists of physico-chemical treatment (pre-chlorination with NaClOat 15% and sand filter) followed by ultraviolet (UV) disinfection(post-chlorination with cationic electrolyte in a tank of accumu-lation and dosage).

Table 3 shows the amounts of input and materials entering thesystems examined.

The LCA software SimaPro 7.2 was used to carry out the impactassessment with reference to the following categories: abioticdepletion (AD), which is related to extraction of minerals and fos-sil fuels due to inputs in the system; global warming potential(GWP) or climate change; ozone layer depletion (OLD) as the con-tribution of substances that deplete the ozone stratospheric layer,particularly trichlorofluoromethane (CFC-11, also known as freon-11); photochemical oxidation (PO), which represents the formationof reactive substances (mainly ozone) which are detrimental tohuman health and ecosystems and which also may damage crops;air acidification (AA), that describes the fate and deposition of acid-ifying substances on soil, groundwater, surface water, organisms,ecosystems and materials (buildings); eutrophication (EU), thatincludes all impacts due to excessive levels of macronutrients inthe environment caused by emissions of nutrients to air, water andsoil, and ecotoxicity potential (EP). The last is the combined result offreshwater aquatic ecotoxicity, marine aquatic ecotoxicity, humantoxicity, and terrestrial ecotoxicity. The most important toxic sub-stances are heavy metals, persistent organic pollutants, and volatileorganic compounds (Pasqualino et al., 2010).

Particularly, for all categories, the environmental impact ofSS was determined as the anthropic impacts related to farm

Table 4Energy consumption for the examined orchard systems per land unit. Conventionalsystem (CS) and sustainable system (SS).

Agricultural operations CS SS

MJ ha−1

Pruning 310 393Pruning residues cutting – 4316Diseases control – 8832Weed control – 6474Soil tillage 4478 –Irrigation – 1305Fertilization 771 3230Harvesting 4733 13,741Total energy input 10,293 38,291

operations (pruning and pruning residues cutting, spontaneousweed cutting, diseases control, installation of the irrigation system,mechanical harvesting), calculated by means of SimaPro software,plus the impacts related to the wastewater treatment taken fromliterature, less the avoided impacts linked to the fertilizers savingthanks to the particular chemical composition of the treatedwastewater used and the nutrient supply coming from the pruningmaterial recycling.

3. Results and discussion

3.1. Energy consumption per land unit

In terms of land unit (ha), SS consumed about four times moreenergy than CS (Table 4). This is explained by a larger number offarm operations and the increased mechanization of agriculturalpractices. In particular, in SS, harvesting, together with diseases andweed control, consumed the largest amount of energy used (about76%). Likewise, harvesting was the largest energy-consuming oper-ation in the conventional model (46%) followed by soil tillage (44%)(Table 4). In fact, in both systems up to 80% of the energy consump-tion is due to the use of machineries (particularly maintenance,lubricants, and diesel fuel) (Table 5). Differently, Kaltsas et al. (2007)found that irrigation and fertilizer application were the highest ofall energy inputs in either conventional and organic olive groves.

3.2. Profitability per hectare

Table 6 summarizes the economic results per hectare of bothsystems found by Palese et al. (2013). The TO includes sales of tableand oil olives: in the 2009–2010 campaign, on Ferrandina mar-ket, the prices were D 400 per t−1 and D 1150 per t−1, respectively.The SS produced a TO about three times larger than CS, mostlydue to the higher quality of olive production (table olives). Notethat both systems are heavily influenced by labour-intensive oper-ations: harvesting and pruning are 90% and 75% of PC in CS and in

Table 5Energy consumption and its distribution in the two management systems, conven-tional system (CS) and sustainable system (SS).

CS SS

MJ ha−1 % MJ ha−1 %

Labour 308 3 707 2Machinery and maintenance 1125 11 3437 9Diesel fuel 7521 73 29,029 76Lubricant 208 2 803 2Fertilizers 402 4 1016 3Chemicals – – 330 1Irrigation system – – 1305 3Materials (plastic containers) 728 7 1684 4Total energy input 11,074 100 38,291 100

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Table 6Total output, production costs and gross profit (mean 2001–2008) calculated for thetwo management systems, conventional system (CS) and sustainable system (SS).

CS SS

(D ha−1)

Oil olives sales 723 137Table olives sales 2154 9542Total output 2877 9679Total production costs 1360 3403Gross profit 1517 6276

Table 7Production costs (mean 2001–2008) calculated for the two management systems,conventional system (CS) and sustainable system (SS).

Agricultural operations CS SS

D ha−1

Pruning 571 726Pruning residues cutting – 113Pest and diseases control – 362Weed control – 169Soil tillage 91 –Irrigation – 65Fertilization 42 144Harvesting 656 1824Total production costs 1360 3403

SS, respectively (Table 7). Also Artukoglu et al. (2012) argued that inTurkey the most important cost item is the labour used especiallyin olive harvest operations.

Finally, both systems reached a positive GP per hectare; nev-ertheless, SS was four times more profitable than CS (Table 6).Importantly, SS produced quite a regular income over the consid-ered years thanks to the annual yield, while CS guaranteed a GP onalternate years (Palese et al., 2013).

3.3. Environmental impact per land unit

Table 8 shows the life cycle impacts per hectare produced bythe two orchard management systems in comparison. The landfunctional unit provides explicit information on the intensity ofagricultural inputs and operations. The results show that SS led tohigher environmental impacts per land unit, particularly in termsof ecotoxicity potential and abiotic depletion (Fig. 1).

In SS, harvesting, wastewater treatment, and pest and diseasecontrol were the operations that caused major impacts (Fig. 2). Withrespect to harvesting, the use of diesel fuel caused above all OLD,EP and AD. At the same time, the treatment of wastewater causedmainly GWP, EU, AA and PO but not EP. Instead, the production ofpesticides gave rise mainly to EP, OLD, and PO.

Table 8Life cycle impacts per hectare calculated for the two management systems: conven-tional system (CS) and sustainable system (SS). Impact categories: abiotic depletion(AD); global warming potential (GWP); ozone layer depletion (OLD); ecotoxicitypotential (EP); photochemical oxidation (PO); air acidification (AA); eutrophication(EU).

Impact categories Environmental impact ha−1

CS SS

AD (kg Sb eq) 5.96 24.64GWP (kg CO2 eq) 411.29 723.15OLD (kg CFC-11 eq) 0.00 0.00EP (kg 1,4-DB eq) 189626.24 607197.55PO (kg C2H4) 0.11 0.45AA (kg SO2 eq) 2.00 6.17EU (kg PO4–3 eq) 0.25 0.48

Fig. 1. Normalization of impact categories of the examined systems, conventionalsystem (CS) and sustainable system (SS).

As Meneses et al. (2010) noted, a toxicity risk assessment, tak-ing into account some key pollutants such as pharmaceuticals andmetabolites, would be interesting to test the final water quality.This latter vary according to the chemistry of the wastewater matrixand the treatment applied, and this will therefore affect final appli-cation of the reclaimed water. But according to Amores et al. (2013),a tertiary treatment allows improvement of physical, chemical andbiological properties of wastewater similar to its natural state andto be returned to natural ecosystems (rivers or the sea). After thisprocess, water can be used for irrigation and, moreover, it has anutrient content (ammonia nitrogen, nitrates and nitrites, potas-sium and phosphorus) that can replace chemical fertilizers (Amoreset al., 2013). With respect to our experimental context, Palese et al.(2009) found that municipal wastewater, reclaimed according tolow cost simplified schemes, has been used successfully for the safeirrigation of the olives although its hygienic quality was often overthe limits set by the Italian Government (Decree No. 3, 02/05/2006,Ministry for Environment) and WHO (1989).

Also in CS, the diesel fuel consumed for harvesting and soil tillagetogether with the production of chemical input utilized in fertiliza-tion (ammonium nitrate), caused the major impacts in almost allcategories (Fig. 3).

Table 9Energy consumption, production costs and impact assessment of the global warmingpotential (GWP) referring to 1 kg of olives: comparison between the two manage-ment systems, conventional system (CS) and sustainable system (SS).

CS SS

Total energy input (MJ kg−1 olives) 2.80 4.43Production costs (D kg−1 olives) 0.37 0.39Farm net income (D kg−1 olives) 0.41 0.73GWP (kg CO2 eq kg−1 olives) 0.11 0.08

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Fig. 2. The contribution of the agricultural operations to impact categories per hectare for sustainable system.

3.4. Impact comparison per output unit

Table 9 reports the energy consumption, production costs, pro-fitability and impact assessment of the Global Warming Potentialreferring to the product functional unit (1 kg of olives).

From this point of view, the data comparison between the twosystems gives a rather different picture. The SS is confirmed to bethe most energy consuming system, meanwhile its olive productioncosts are only slightly higher than CS, in spite of the higher number

Fig. 3. The contribution of the agricultural operations to impact categories perhectare for conventional system.

of operations required. The greater productivity of SS gives a more‘sustainable’ kg of olives, at least regarding income and kg of CO2eq emitted.

Referring to GWP, our data (Table 9) showed much lower GHGemissions per kg of drupes than emissions estimated by Salomoneand Ioppolo (2012) (from 0.39 to 0.43), Neri et al. (2012) (0.79 fororganic olives and 2.87 for conventional olives), and Cappellettiet al. (2010) (0.5).

4. Conclusions

The combined use of various methodologies (energy and eco-nomic analysis, LCA) could be useful to provide information forpolicy makers and producers in choosing sustainable managementsystems or products.

Under our experimental conditions, the sustainable system wasmore productive and more profitable thanks to the higher yieldand its superior quality, which means that it can negotiate bettermarket price than the conventional system. Referring to land unit,the SS for its higher number of operations led to higher environ-mental impacts and consumed more energy than CS. Differently,the SS emitted less GHGs per kg of olives harvested thanks to itsgreater productivity. At the same time, the use of treated wastewa-ter for irrigation can save significant fertilizers amounts, reducingenvironmental impacts, and reduce water volumes that wouldotherwise be discharged into the environment helping mitigateregional or seasonal water scarcity.

Finally, methodologies for energy and environmental analysisneed to be further developed in order to better fit agricultural sys-tems.

The next challenge will be to find the opportune strategies totransfer the sustainable management system to larger areas.

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Acknowledgement

This study was financially supported by the Ministerodell’Università e della Ricerca, Italy (MIUR PRIN 2008 Project ‘Ciclodel carbonio in ecosistemi produttivi arborei’ and MIUR PRIN 2009Project ‘Riutilizzo di acque reflue: contaminanti emergenti e prob-lematiche operative’).

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