Introduction

Kiwi is the common name of fruits acquired from the hybrids between Actinidia deliciosa and other Actinidia species. It is a native of eastern China. Cultivated for the first time in 1904 by growing fruits from seed, kiwi was particularly grown commonly after 1970’s, in many regions including South Africa, Italy, Japan, Spain, Australia, Chile and California (Ferguson 1991; Yılmaz 2016). The global kiwi production is 3,261,474 t per annum and China (54%), Italy (14%) and New Zealand (12%) are the leading producers. Turkey is ranked 7th with a production of 41,635 t (FAO 2013; Yılmaz 2016). Kiwi is also important for human health. Kiwi is rich in vitamin C. In addition, it also contains proteins and several mineral salts. It has been scientifically proven that some substances found in kiwi juice are preventing the formation of compounds leading to cancer. Its benefits on breathing are used in the treatment of asthma and cough. Another advantage of kiwi consumption is the increased resistance against cold during winter months (Anonymous, 2011; Yılmaz 2016).

Ratio and econometric based energy analyses are mostly used to determine energy efficiency as well as environmental impact. Such studies are helpful in defining the efficiency of energy used. This, in turn, may help to avoid unnecessary energy use and environmental damage (Göktolga et al. 2006; Barut et al. 2011; Ozalp et al. 2018). Furthermore, energy use in agriculture must be effective because it is a precondition to achieve sustainable agriculture as it decreases production costs and pollution through financial savings and preservation of natural resources (Uhlin 1998; Flores et al. 2016; Ozalp et al. 2018). Energy analysis does require several economic and technical studies and the main reason to perform such analysis is to reveal if a service or product to be made available to the market is viable in terms of energy use efficiency. When assessing production efficiency, a reliable approach would be to compare total energy value of inputs used in agricultural production processes with energy value of the obtained product (Upton et al. 2010; Yener and Oğuz 2019).

Different studies have been conducted on energy efficiency of fruit production. For example, studies were done on energy efficiency analysis of kiwi fruit (Mohammadi et al. 2010), apricot (Gezer et al. 2003), peach (Göktolga et al. 2006), sweet cherry (Demircan et al. 2006), grape (Ozkan et al. 2007), cherry (Kizilaslan 2009), carrot (Çelik et al. 2010), banana (Akcaoz 2011), lemon (Bilgili 2012), avocado (Astier et al. 2014), mango (Ram and Verma 2015), almond (Beigi et al. 2016), pear (Aydın et al. 2017), apple (Çelen et al. 2017), strawberry (Baran et al. 2017a), walnut (Baran et al. 2017b), pomegranate (Ozalp et al. 2018), chestnut (Gökdoğan et al. 2019), nectarine (Oğuz et al. 2019) etc. Although many experimental studies were done on energy efficiency in agriculture, there is no specific study on the energy efficiency of kiwi fruit production in literature. In this study, it was aimed to determine the energy and economic efficiency of kiwi fruit production.

Materials and Methods

Mersin province is located between 36–37° north latitudes and 33–35° east longitudes. Land border of the province is 608 km and sea border is 321 km and the total land area is 15,853 km2 (Turkey Republic Mersin Governership 2019). This study was performed to determine the energy efficiency and economic analysis of kiwi fruit production for the 2018–2019 production season in Mersin province in Turkey. Survey data were collected in 2019 and the farms to be studied were selected in accordance to full counting method (Karagölge and Peker 2002) and the survey was applied (face to face) to these farms. In order to determine the energy efficiency and economic analysis in the production of kiwi fruit, a survey was made at 10 interviewed farms (can be reached) of kiwi fruit production in Çağlarca region of Mersin province. According to results of the study, human labour energy, machinery energy, chemical fertilizers energy, organic fertilizer energy, chemical energy, diesel fuel energy, irrigation water energy and electricity energy were energy inputs. Kiwi fruit was the output.

Table 1 indicates the calculation of the values of the inputs and output of kiwi fruit production. Input data balancing was conducted by using Microsoft Excel program before tabulating the results, Table 2, and related to kiwi fruit production inputs and output values and the calculations were performed in Table 3. Koctürk and Engindeniz (2009) reported that, “The input energy is also classified into direct and indirect, and renewable and non-renewable forms. The indirect energy consists of pesticide and fertilizer, while the direct energy includes human and animal power, diesel and electricity used during the production process. On the other hand, non-renewable energy includes petrol, diesel, electricity, chemicals, fertilizers, machinery, and renewable energy consists of human and animal (Mandal et al. 2002; Singh et al. 2003)”. Energy inputs of kiwi fruit production, in the forms of direct, indirect, renewable and non-renewable energy were given in Table 4. Economic analysis of kiwi fruit production was shown in Table 5. Previous energy efficiency studies were used when determining the energy equivalent and energy equivalent was calculated by adding energy equivalents of all inputs in MJ unit.

Table 1 Energy equivalents in kiwi fruit production
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Table 2 Energy balance in kiwi fruit production
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Table 3 Energy use efficiency indicators in kiwi fruit production
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Table 4 Energy input forms for kiwi fruit production
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Table 5 Net return and benefit-cost ratio of the kiwi fruit production
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IKA® made C200 bomb calorimeter device was used for the calorific values of kiwi fruit product. In order to measure, fuel (~ 0.1 g), filled with oxygen for full combustion with sufficient amount of pressure (~ 30 bars), was combusted inside the calorimeter bomb, then the full bomb calorimeter was placed into and filled with a sufficient amount of tap water (~ 2000 mL at 18–25 oC ± 1 oC). A calorific value in MJ kg−1 unit was assigned to the device. Calorific value reading of kiwi fruit samples was taken on 3 consecutive occasions before reporting an average value. In order to determine the energy efficiency in kiwi fruit production, “Energy efficiency, energy productivity, specific energy and net energy were calculated by using the following formulas (Mandal et al. 2002; Mohammadi et al. 2008, 2010)”.

$$\text{Energy efficiency}=\frac{\text{Enerji output}\,\left(\frac{\mathrm{MJ}}{\mathrm{ha}}\right)}{\text{Enerji input}\,\left(\frac{\mathrm{MJ}}{\mathrm{ha}}\right)}$$
(1)
$$\text{Energy productivity}=\frac{\text{Kiwi fruit output}\,\left(\frac{\mathrm{kg}}{\mathrm{ha}}\right)}{\text{Energy input}\,\left(\frac{\mathrm{MJ}}{\mathrm{ha}}\right)}$$
(2)
$$\text{Specific energy}=\frac{\text{Energy input}\,\left(\frac{\mathrm{MJ}}{\mathrm{ha}}\right)}{\text{Kiwi fruit output}\,\left(\frac{\mathrm{kg}}{\mathrm{ha}}\right)}$$
(3)
$$\text{Net energy}=\text{Energy output }(\mathrm{MJ\,}\mathrm{ha}^{-1})-\text{Energy input }(\mathrm{MJ\,}\mathrm{ha}^{-1})$$
(4)

Results and Discussion

The average amount of kiwi fruit produced per hectare during the 2018–2019 production season in the kiwi fruit farms was calculated as 21,395.58 kg. According to the study results (Table 2), the energy inputs in kiwi fruit production were calculated respectively as 17,359.20 MJ ha−1 (55.80%) chemical fertilizers energy, 7543.83 MJ ha−1 (24.25%) electricity energy, 4256.13 MJ ha−1 (13.68%) organic fertilizer energy, 830.24 MJ ha−1 (2.67%) human labour energy, 731.62 MJ ha−1 (2.35%) irrigation water energy, 253.40 MJ ha−1 (0.81%) diesel fuel energy, 129.60 MJ ha−1 (0.42%) machinery energy and chemicals energy 5.77 MJ ha−1 (0.02%). Similarly, in previous agricultural studies related to fruit production, Mohammadi et al. (2010) calculated that the chemical fertilizers application energy had the biggest share by 47.23% in kiwi fruit production, Ozkan et al. (2004b) calculated that chemical fertilizers application energy had the biggest share by 44.42% in orange production, Demircan et al. (2006) calculated that fertilizer application energy had the biggest share by 45.35% in sweet cherry production, Akcaoz et al. (2009) calculated that fertilizer application energy had the biggest share by 40.22% in pomegranate production, Mohammadshirazi et al. (2012) calculated that fertilizer application energy had the biggest share by 52.40% in tangerine production etc.

Kiwi fruit, energy input, energy output, energy output-input ratio, specific energy, energy productivity and net energy in kiwi fruit production were calculated as 21,395.58 kg ha−1, 31,109.78 MJ ha−1, 67,217.49 MJ ha−1, 2.16, 1.45 MJ kg−1, 0.69 kg MJ−1 and 36,107.71 MJ ha−1, respectively (Table 3). In previous agricultural production studies, Mohammadi et al. (2010) calculated (kiwi fruit) energy output-input ratio as 1.54, Demircan et al. (2006) calculated (sweet cherry) energy output-input ratio as 1.23, Akdemir et al. (2012) calculated (apple) energy output-input ratio as 1.51, Tabatabaie et al. (2013) calculated (pear) energy output-input ratio as 0.51, Nabavi-Pelesaraei et al. (2013) calculated (peanut) energy output-input ratio as 4.53, Koctürk and Engindeniz (2009) calculated (grape) energy output-input ratio as 8.64, Baran et al. (2017a) calculated (strawberry) energy output-input ratio as 0.25, Ozalp et al. (2018) calculated (pomegranate) energy output-input ratio as 1.51, Gökdoğan et al. (2019) calculated (chestnut) energy output-input ratio as 11.49, Oğuz et al. (2019) calculated (nectarine) energy output-input ratio as 1.86 etc.

The distribution of inputs, used for the production of kiwi fruit and categorized as direct, indirect, renewable and non-renewable energy groups, was given in Table 4. The consumed total energy input in kiwi fruit production could be classified as 30.08% direct, 69.92% indirect, 18.70% renewable and 81.30% non-renewable. Similarly, kiwi fruit (Mohammadi et al. 2010), orange (Ozkan et al. 2004b), open-field grape (Ozkan et al. 2007), greenhouse grape (Ozkan et al. 2007), apple (Akdemir et al. 2012), cherry (Aydın and Aktürk 2018), nectarine (QasemiKordkheili et al. 2013), peanut (Nabavi-Pelesaraei et al. 2013), pear (Aydın et al. 2017), cherry (Kizilaslan 2009) etc. In this study, non-renewable energy sources composed 81.30% (25,291.80 MJ ha−1) of the total energy input, which was higher than that of the renewable resources 18.70% (5817.98 MJ ha−1). Energy efficiency was increased, because usages of organic fertilizer were used instead of chemical fertilizers.

Economic efficiency of kiwi fruit production was given in Table 5. The total cost of kiwi fruit production per kg was given in Turkish Lira (TL), which was equal to 0.79 US dollars (US$) in 2018 (on average). Demircan et al. (2006) reported that, “The net return was calculated by subtracting the total cost of production per hectare (variable + fixed cost) from the gross value of production”. Profit margin per kg of kiwi fruit (TL kg−1) was calculated as 1.40. This can be explained such that the net return of 1.58 TL was obtained per 1 TL invested and was a cost effective business for 2018–2019 season of kiwi fruit production. In previous agricultural studies, Mohammadi et al. (2010) calculated (kiwi fruit) benefit-cost ratio as 1.94, Ozkan et al. (2004b) calculated (orange) benefit-cost ratio as 2.37, Ozkan et al. (2004b) calculated (lemon) benefit-cost ratio as 1.89, Ozkan et al. (2004b) calculated (mandarin) benefit-cost ratio as 1.88, Esengun et al. (2007) calculated (apricot) benefit-cost ratio as 1.11–1.19, Tabatabaie et al. (2012) calculated (plum) benefit-cost ratio as 4.18–2.46, Tabatabaie et al. (2013) calculated (pear) benefit-cost ratio as 3.11, Moradi et al. (2015) calculated (watermelon) benefit-cost ratio as 4.72–3.92, Ram and Verma (2015) calculated (mango) benefit-cost ratio as 3.74, Oğuz et al. (2019) calculated (nectarine) benefit-cost ratio as 2.02.

Conclusions

In this study, an energy efficiency and economic analysis was conducted in kiwi fruit production. According to the results, kiwi fruit production is a profitable activity in terms of energy output-input ratio (2.16). The economic efficiency in kiwi production was calculated as 1.58, and according to the answers given by producers to the survey, high input prices are lower compared to energy effective. The fact that economic efficiency is 1.58 is an indication of the profitability of kiwi production. Kiwi fruit production was a cost effective business based on the data from the 2018–2019 production season in terms of energy and economic efficiency.

In kiwi fruit production, total input energy was calculated as 31,109.78 MJ ha−1 and total energy output was calculated as 67,217.49 MJ ha−1. The energy efficiency, specific energy, energy productivity and net energy calculations were calculated in kiwi fruit production respectively as 2.16, 1.45 MJ kg−1, 0.69 kg MJ−1 and 36,107.71 MJ ha−1. The consumed total energy input in kiwi fruit production were classified as 30.08% direct, 69.92% indirect, 18.70% renewable and 81.30% non-renewable. Among the inputs used for kiwi fruit production, the highest input is chemical fertilizers with a ratio of 55.80%. Increasing the use of organic fertilizer and decreasing use of chemical fertilizer in kiwi production will increase the energy efficiency even more.

More extensive use of renewable resources in agriculture is important to preserve natural resources and effectively prevent environmental issues (Kamburoğlu Çebi et al. 2017). Another issue to consider is the practise of a sound managerial approach in enterprises with regards to economic, environmental and energy analysis in production systems. Achieving an efficient, sustainable and economical energy use can be possible through energy management in enterprises (Yener and Oğuz 2019).