ReseaRch PaPeR Journal of Agricultural and Marine Sciences Vol. 24 : 24– 29 DOI: 10.24200/jams.vol24iss1pp24-29 Reveived 12 Dec 2018 Accepted 5 Mar 2019 Evaluation of energy use efficiency for greenhouse cucumber production in Barka, Oman *Nawal Khamis Al-Mezeini, Abdulrahim M. Al-Ismaili, Said M. Tabook *Nawal Khamis Al-Mezeini ( ) nawal@squ.edu.om, Department of Soils, Water and Agricultural Engineering, College of Agricultural and Marine Sciences, Sultan Qaboos University, Box 34, Al-Khod, 123. Introduction Greenhouses provide higher production and more efficient water consumption in compari-son to open-field cropping (Abdel-Rahman and Abdel-Magid 1993; MAF 2009). As a result, the number of greenhouses in Oman was increased 5 times between 2003-2015 (Al-Ismaili et al. 2017). Cucumber (Cucum- is sativus L.) is the most commonly grown greenhouse vegetable worldwide (Mohammadi and Omid 2010; Omid et al. 2011) and this is also the case in Oman where more than 90% of greenhouses are used for cu- cumber cultivation (MAF 2013). This could be attribut- ed to its fast growth, and good nutritional and economic value (Al-Kiyoomi 2006; Al-Sadi et al. 2010). Although greenhouses provide high yield, they also require high energy consumption to achieve this yield (Bolandnazar et al. 2014; Heidari and Omid 2011). Energy-use efficiency (EUE) is considered one of the most important factors contributing to agricultural sustainability (Firoozi et al. 2014). Such energy analysis helps in managing greenhouse production system by identifying the wasteful energy parameters and propos- ing management approaches (Bolandnazar et al. 2014). EUE in greenhouse production has been used by many researchers to assess greenhouse cropping systems (Hamedani et al. 2011; Taki et al. 2013). For instance, Mohammadi and Omid (2010) investigated the EUE of greenhouse cucumber production. Results revealed that cucumber production consumed 148.836 GJ ha-1 of the total energy input and diesel fuel was found to be the main energy consuming factor. In another study, Heidari and Omid (2011) investigated the EUE (output-input ra- tio) for cucumber and tomato greenhouse production. Results indicated that the EUE was 1.48 and 0.69 for حتليل كفاءة إستخدام الطاقة إلنتاج حمصول اخليار يف بركاء، ُعمان نوال املزيين وعبدالرحيم اإلمساعيلي* وسعيد تبوك Abstract. Sustainable agricultural production can be assessed through energy-use efficiency (EUE). This paper aims to evaluate the EUE for cucumber greenhouse production in Oman. Data were obtained through face to face inter- view with farmers. Results indicated that total energy inputs (e.g. electricity, water, fertilizers and chemicals) and total energy output (cucumber yield) were 1171.637 GJ ha-1 and 89.943 GJ ha-1, respectively. The highest energy input in the greenhouse production was electricity, consuming 88% of total energy input. Electricity had the highest impact in cucumber greenhouse production and 99% of this electricity goes to cooling the greenhouse. When all energy inputs were classified into their different forms; direct (D) and indirect (ID), and renewable (R) and non-renewable (NR), the highest portion of total energy forms in greenhouse cucumber production was for D and NR energy. The EUE and energy productivity (EP) were found to be 0.08 and 0.10 ton GJ-1, respectively. The energy use in greenhouse cucumber production was found to be inefficient and solar energy needs to be considered to improve the sustainable cucumber greenhouse production in Oman. Keywords: Energy-use-efficiency; cucumber; greenhouse; energy productivity; energy forms. املســتخلص: ميكــن تقييــم اإلنتــاج املســتدام للزراعــات احملميــة مــن خــال حتليــل كفــاءة إســتخدام الطاقــة، هتــدف هــذه الدراســة إىل تقييــم كفــاءة إســتخدام الطاقــة يف البيــوت احملميــة املزروعــة مبحصــول اخليــار يف ســلطنة عمــان، مت احلصــول علــى البيانــات عــن طريــق إجــراء مقابــات مــع املزارعــن )وجهــا لوجــه(، وأوضحــت النتائــج إن الكميــة اإلمجاليــة للطاقــة املســتخدمة والناجتــة مــن البيــوت احملميــة وصلــت اىل 1171.637 و 89.943 )جيجاجول/هكتار(علــى التــوايل، وتعــد الكهربــاء أكــر مدخــات البيــوت احملميــة املســتهلكة للطاقــة حيــث يقــدر إســتهاكها للطاقــة مبعــدل %88 مــن إمجــايل الطاقــة املســتخدمة، لذلــك تعــد الكهربــاء أكــر العوامــل املســتهلكة للطاقــة وقــد وجــد أن معظــم الكهربــاء يتــم إســتهاكها يف تريــد البيــوت احملميــة، وعندمــا مت تقســيم الطاقــة إىل أنواعهــا األربعــة وهــي الطاقــة املباشــرة والغــر مباشــرة واملتجــددة والغــر متجــددة، وجــد أن الطاقــة املباشــرة والغــر متجــددة هــي أكــر أنــواع الطاقــة املســتخدمة يف البيــوت احملميــة، كمــا توصلــت النتائــج إىل أن كفــاءة اســتخدام الطاقــة وانتــاج الطاقــة مــن البيــوت احملميــة وصلــت الى0.08 و 0.01 )طــن/ جيجاجول(علــى التــوايل، ويف اخلتــام فــإن كفــاءة اســتخدام الطاقــة يف البيــوت احملميــة غــر فعالــة، ومــن أجــل حتقيــق اإلســتدامة يف الزراعــة احملميــة، فإنــه ينصــح بإســتخدام الطاقــة الشمســية إلنتــاج الطاقــة الــي حيتاجهــا البيــت احملمــي. الكلمات املفتاحية: كفاءة إستخدام الطاقة، اخليار، البيت احملمي، إنتاجية الطاقة، أنواع الطاقة. 25Research Article Al-Mezeini, Al-Ismaili, Tabook tomato and cucumber, respectively which reflected an inefficient energy use in cucumber greenhouse produc- tion. Diesel fuel was also the major contributing factors for both cucumber and tomato production (Mohamma- di and Omid 2010). In strawberry greenhouses a total energy of 805.380 GJ ha-1 were consumed (Banaeian et al. 2011) and diesel fuel was the major energy depleting factor with 78% of the total energy. It appears thus that diesel fuel is the major variable influencing the EUE of greenhouse production. In these studies, diesel fuel was mainly used to power heaters to provide temperature suitable growing envi- ronment. In Oman, where weather conditions are gen- eraly hot, heaters are not necessary but cooling systems (generally fan-pad evaporative cooling systems) are used instead. In such conditions, EUE of cooled greenhous- es needs to be evaluated. Therefore, this study aimed to investigate the EUE of evaporative-cooled greenhouse systems in Oman using major energy performance in- dicators for instance EUE, energy productivity (EP) and net energy (NE). Table 1. The energy equivalents correspond to each inputs and output use in greenhouse cucumber production. Inputs and output (unit) Energy equivalent (MJ Unit-1) Reference Inputs: Human labour (h) 1.96 (Taki et al., 2013) Machinery (h) 13.06 (Mohammadi and Omid 2010; Ozkan et al. 2007) Chemical fertilizers (kg): Nitrogen (N) 66.14 (Mohammadi and Omid 2010; Shrestha 1998) Phosphate (P2O5) 12.44 (Mohammadi and Omid 2010; Shrestha 1998) Potassium (K2O) 11.15 (Mohammadi and Omid 2010; Shrestha 1998) Calcium 1.12 (Mohammadi and Omid 2010) Micro 120.00 (Banaeian et al. 2011; Mohammadi et al. 2008) Manure (kg) 0.3 (Mohammadi and Omid 2010) Chemicals (kg) 120.00 (Mohammadi and Omid 2010) Water (m3) 1.02 (Mohammadi and Omid 2010; Mousavi-Avval et al. 2011) Electricity (kWh) 11.93 (Hatirli et al. 2005; Mousavi-Avval et al. 2011) Seeds (kg) 1.00 (Mohammadi and Omid 2010) Outputs: Cucumber (kg) 0.8 (Mohammadi and Omid 2010) Table 2. The statistical summary of energy inputs (GJ ha-1) and output (ton ha-1) for cucumber production. Inputs (unit) Mean SD Min Max A. Inputs (GJ ha-1) Human labour 7.110 3.653 1.372 14.112 Machinery 1.221 0.496 0.560 1.959 Chemical fertilizers 62.582 55.535 18.793 180.802 Manure 0.008 0.004 0.000 0.015 Chemicals 5.775 3.370 1.714 10.971 Water 6.323 2.499 2.463 9.748 Electricity 1025.352 360.885 557.157 1550.185 Seeds 0.001 0.000 0.001 0.001 B. Output Cucumber (ton ha-1) 98.937 28.321 58.583 149.349 26 SQU Journal of Agricultural and Marine Sciences, 2019, Volume 24, Issue 1 Evaluation of Energy: Use Efficiency for Greenhouse Cucumber Production in Barka, Oman Materials and Methods Data were collected through a survey of 8 cucumber greenhouses farmers in Barka region, Sultanate of Oman who agreed to participate in the survey. Cucumber is the most cultivated crops in greenhouses. Data were obtained through face to face interviews of the farmers which encompassed questions related to all expenses related to the greenhouses for three months (seeding-to-harvesting) during the cropping season (summer 2017). The greenhouses were Quonset with polyethylene covering and fan-pad evaporative cooling system (Fig. 1). All greenhouses were of similar type, covering material and cooling system. The standard dimensions of greenhouses were 0.035 ha. The average row and plant spacing were 133 cm and 50 cm, respectively. Cucumber plants were trained to grow vertically in the greenhouse (Fig. 2). The average ambient temperature was around 29°C during the study period. The 8 inputs considered in this study were human la- bor, machinery, chemical fertilizers chemicals, manure, electricity, water for irrigation and seeds and the single output was yield. The selection of the inputs was based similar studies from which we omitted diesel fuel which is not used in the greenhouses surveyed (Mousavi-Avval et al. ,2011; Mohammadi and Omid 2010 ; Omid et al. 2011). For energy performance analysis, all inputs and out- put were converted into single energy unit, with conver- sion values obtained from different sources (Table 1). EUE, EP and NE were calculated using Equations 1-3, respectively (Mohammadi et al. 2008; Ozkan et al. 2011). EUE = Energy Output (GJ ha-1)/Energy Input (GJ ha-1) (Eq. 1) EP = Cucumber Output (kg ha-1)/Energy Input (GJ ha-1) (Eq. 2) NE = Energy Output (GJ ha-1)–Energy Input (GJ ha-1) (Eq. 3) In general, the energy inputs used in agricultural pro- duction systems are classified into direct (D) and indi- rect (ID), and renewable (R) and non-renewable (NR) energies (Mohammadi et al. 2010; Mohammadi et al. 2008). The direct energy inputs involve human labour, water, and electricity, the indirect energy involves seeds, fertilizers, manures, chemicals, and machinery, the re- newable energy inputs includes human labour, seeds, manure and water and the non-renewable energy ac- counts for chemicals, fertilizers, machinery and electric- ity. Results and Discussion The descriptive summary of inputs used for cucumber production and output are presented in Table 2. There Table 3. Amount of inputs and output in cucumber production. Inputs (unit) Quantity per unit area (ha) Total energy equivalent (GJ ha-1) Percentage (%) of total energy SD* A. Inputs Human labour (h) 3627.454 7.110 0.607 3.653 Machinery (h) 93.464 1.221 0.104 0.496 Chemical fertilizers (kg): 2035.497 59.847 5.108 38.179 Nitrogen 609.533 40.315 3.441 Phosphate (P2O5) 610.364 7.593 0.648 Potassium (K2O) 752.171 8.387 0.716 Calcium 34.143 0.038 0.003 Micro 29.286 3.514 0.300 Manure (kg) 20535.714 6.161 0.526 3.239 Chemicals (kg) 48.129 5.775 0.493 3.370 Water (m3) 6199.506 6.323 0.540 2.499 Electricity (kWh) 85947.357 1025.352 87.514 360.885 Seeds (kg) 0.857 0.001 0.000 Total energy input (GJ ha-1) 1171.637 100.000 B. Output Cucumber (ton ha-1) 112.429 89.943 100.000 32.180 Total energy output (GJ ha-1) 89.943 * Represents the standard deviation of energy inputs (GJ ha-1) and energy output (ton ha-1) 27Research Article Al-Mezeini, Al-Ismaili, Tabook were variations among inputs and output which implied that there was a potential efficiency improvement for cu- cumber greenhouse farmers. Thus, EUE of greenhouses was evaluated hereafter. The inputs with their equivalent energy values con- sumed in cucumber production for the studied green- houses are illustrated in Table 3. Average yield was 112.428 ton ha-1 which is equivalent to a total ener- gy output of 89.943 GJ ha-1. Results also revealed that 1171.637 GJ ha-1 of total energy input were needed in the production of cucumber crop. Electricity, chemicals and chemical fertilizers were calculated as 1025.352, 5.775 and 59.847 GJ ha-1, respectively. Among all ener- gy inputs, electricity was the highest energy consuming factor with a total of 88% (Fig. 3). This high electricity consumption was further analyzed and the analysis re- vealed that most of this electricity was consumed by the cooling system (Fig. 3) as the temperature sometimes ex- ceeds 50°C (Al-Ajmi and Abdel-Rahman 2001; Al-Sadi et al. 2011). To limit this use of non-renewable energy, it is recommended to investigate the use of alternative power sources such as solar energy to operate the cool- ing system (fans and pumps). The EUF, EP and NE of cucumber production were 0.08, 0.10 tons GJ-1 and -1081 GJ ha-1 respectively (Table 5). In the literature, the EUE for greenhouse cucumber production was considered inefficient when it equals to 0.017 (Zarini et al. 2013) or even as high as 0.64 (Mo- hammadi and Omid 2010). Therefore, the EUE of the surveyed greenhouses in this study was (0.08) should also be considered inefficient. This EUE in cucumber greenhouse production could be increased by either increasing crop yield or by decreasing inputs consump- tion. The average EP (0.10 ton GJ-1) for greenhouse cu- cumber production was lower than the reported values of 0.80 (Mohammadi and Omid 2010), 0.55 (Heidari and Omid 2011) and 0.50 (Omid et al. 2011). This indi- cates that every kilogram of cucumber in the surveyed greenhouses in Oman consumed 5-8 times more input energy than the greenhouses cited above. The high neg- ative value of NE (-1081.690 GJ ha-1) indicates that en- ergy being lost in cucumber production. This can be at- tributed to the high electricity consumption consumed by the cooling systems. In Iran, Omid et al. (2011) and (Bolandnazar et al. 2014) found that the NE for green- house cucumber production gave also negative values (-55.553 and -149.317 GJ ha-1, respectively) due to the high fuel consumption for heating (more than 50% of the total inputs energy). Since, energy consumption for temperature adjustment (heating or cooling system) is the highest among all inputs in greenhouse cucumber Table 4. Energy forms (D, ID, R and NR) in cucumber produc- tion in Oman. Form of energy Energy value (GJ ha-1) % of total energy input D a 1038.785 88.66 IDb 73.005 6.23 R c 19.595 3.32 NRd 1092.20 93.219 Total energy input 1171.637 100.00 a -involves human labour, water, electricity. b -involves seeds, fertilizer, manure, chemicals, machinery. c -involves human labour, seeds, manure, water. d -involves chemicals, fertilizer, machinery, electricity. Table 5. Energy use efficiency in cucumber production in Oman. Items Unit Value SD E input GJ ha -1 1171.64 374.58 E output GJ ha -1 89.94 25.75 Yield ton ha-1 112.43 32.18 EUE unitless 0.08 0.03 EP ton GJ-1 0.10 0.04 NE GJ ha-1 -1081.69 361.78 Figure 1. Quonset greenhouse with polyethylene covering and (a) fan-(b) pad evaporative cooling Figure 2. The greenhouse vertical cultivation 28 SQU Journal of Agricultural and Marine Sciences, 2019, Volume 24, Issue 1 Evaluation of Energy: Use Efficiency for Greenhouse Cucumber Production in Barka, Oman production; the existing heating/cooling systems need improvement in order to achieve a more efficient energy use and sustainable crop production. The percentage of total energy inputs as D, ID, R and NR energy is shown in Table 4. It was found that the D energy inputs (e.g. human labour, water, electricity) followed by NR energy inputs (e.g. chemicals, fertilizer, machinery, electricity) were the highest energy consum- ers and the R energy forms (e.g. human labour, seeds, manure, water) were the lowest energy consumers. Oth- er investigators, such as, Ozkan et al. (2007), Kizilaslan (2009), Mohammadi and Omid (2010), Banaeian et al. (2011) and Zarini et al. (2013) reported similar out- comes. The tetra-inoculum (Tm+Tc+Gr+Gn) reported high- est average of dry weight of plants which was 710 mg/ plant compared with negative and positive control which was 86 and 479 mg/plant respectively, followed by the treatment of tri-inoculum (Tc+Gr+Gn) which was 602 mg/plant. The combined application of Gr+Gn exhibited significant increase in the dry weight of plant which was 559 mg/plant. Tariq and Magee (1990) found that vola- tile components of garlic extracts inhibited germination of the microconidia, macroconidia and mycelium of the F. oxysporum f. sp. lycopersici in vitro. Al-Rahmah et al. (2013) has been found that ginger extracts has strong fungistatic and fungicidal activities against F. oxysporum and Pythium aphanidermatum with minimal inhibitory concentration. Furthermore, Sahar et al. (2013) proved that foliar application of Topsin-M with concentration of 0.1 % was significantly reduced the disease incidence of Fusarium wilt disease on eggplant. 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