Introduction

The natural range of chestnut in the world are Eastern Asia (China, Korea, Japan), Turkey, Southern Europe and North America. In the Northern hemisphere, it is grown naturally in chestnuts forests, along with local species. The main countries growing are China, Korea, Japan and Mediterranean countries. In Turkey, located in Mediterranean basin, Castanea sativa Mill. (European chestnut) type of chestnut is naturally grown under the humid conditions of forests in Black Sea, Marmara and Aegean Regions of Anatolia (Subaşı 2004; Karadeniz 2013). Chestnuts and many temperate fruit tree species have been grown in Anatolia since ancient times (Soylu 1984; Ertan et al. 2007). The major chestnut fruit growing areas in Aydın province of Turkey, which yield nearly 35% of Turkey’s production (Erincik et al. 2008). According to FAO (2009) data (chestnut fruit), Turkey is the third in the World (Atasoy and Altıngöz 2011). According to 2017 data, Aydın province of Turkey is the first on chestnut with 68,477 decares and 25,423 tons production (TUIK 2017).

Agricultural sector has become more energy-intense to supply more food to rising population and ensure sufficient and adequate nutrition. However, considering restricted natural resources and the impact of using different energy sources on environment and human health; it is important to investigate energy use patterns in agriculture (Hatırlı et al. 2005). Energy is a basic component of economic development because it ensures essential services maintaining the economic activity and increasing the quality of human life. At the farm level, energy use can be classified into four categories: direct, indirect, renewable, and non-renewable resources (Thankappan et al. 2005; Azizi and Heidari 2013). The energy balance is defined as the difference between gross energy of useful products divided by non-renewable energies used to produce them (Risoud 2000; Azizi and Heidari 2013). All inputs and outputs of a cropping system can be expressed in terms of energy. Energy input and output analysis is used to determine the energy efficiency and environmental impact of crop production. This analysis is important to make necessary improvements that will lead to a more efficient and environment-friendly production system (Bojaca and Schrevens 2010; Mobtaker et al. 2010).

Different researches were performed on energy use efficiency analysis of fruit products in Turkey and in the world. For example, studies of fruit were performed on energy use efficiency analysis analysis of citrus (Ozkan et al. 2004a), sweet cherry (Demircan et al. 2006), peach (Göktolga et al. 2006), apricot (Esengün et al. 2007), cherry (Kızılaslan 2009), pomegranate (Canakcı 2010), banana (Akçaöz 2011), nectarine (Qasemi-Kordkheili et al. 2013), apple (Yılmaz et al. 2010), quince (Gündoğmuş 2013), almond (Beigi et al. 2016), walnut (Baran et al. 2017a), plum (Baran et al. 2017b) etc. Although many experimental studies were performed on energy use efficiency analysis in fruit field but there has no study on energy use efficiency evaluation on chestnut fruit production in literature. In this study, it was aimed to perform the energy use efficiency analysis of chestnut fruit production.

Materials and Method

Aydın province is located within the Aegean region of Turkey. Aydın has productive plains in central and western sections, is surrounded by mountains in north and south. It is located on the Great Menderes basin, covering an area of 8007 km2. 55% of the population is depending on farming for their livelihood. Aydın has a major role in Turkey in terms of national agriculture, as indicated by the fact that the province is ranked within the top ten producers in 25 different products (Anonymous 2015). In this study, data acquired and compiled through interviews with chestnut growers from the villages of Nazilli district of Aydın province, where chestnut growing is common, has been used as material.

By calculating the agricultural input energies and output energies were used in chestnut fruit production, the energy use efficiency analysis was done. Total energy input in unit area (ha) constitutes the total energy inputs. Human labour energy, animal labour energy, chemical fertilizers, farmyard manure energy, petrol/gasoline energy and transportation energy were calculated as inputs. The units shown in Table 1 were used to calculate the values of the inputs of chestnut fruit production. Previous energy analysis studies were used when determining the energy equivalent coefficients. The total energy equivalent was calculated by adding energy equivalents of all inputs in MJ unit. In order to determine the energy input-output in chestnut fruit production, “Energy use efficiency, energy productivity, specific energy and net energy were calculated by using the following formulates (Mandal et al. 2002; Mohammadi et al. 2008, 2010)”.

$$\text{Energy use efficiency}= \frac{\text{Energy output}\ \left(\frac{\,\mathrm{MJ}}{\mathrm{ha}}\right)}{\text{Energy input}\,\left(\frac{\mathrm{MJ}}{\mathrm{ha}}\right)}$$
(1)
$$\text{Specific energy}=\frac{\text{Energy input}\ \left(\frac{\,\mathrm{MJ}}{\mathrm{ha}}\right)}{\text{Chestnut fruit output}\,\left(\frac{\mathrm{kg}}{\mathrm{ha}}\right)}$$
(2)
$$\,\text{Energy productivity}= \frac{\text{Chestnut fruit output}\ \left(\frac{\,\mathrm{kg}}{\mathrm{ha}}\right)}{\text{Energy input}\,\left(\frac{\mathrm{MJ}}{\mathrm{ha}}\right)}$$
(3)
$$\text{Net energy }=\text{Energy output }(\mathrm{MJ}\,\mathrm{ha}^{-1})\,-\,\text{Energy input }(\mathrm{MJ}\,\mathrm{ha}^{-1})$$
(4)
Table 1 Energy equivalents in agriculture production
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The results were tabulated in Table 2 and related to chestnut fruit production input-output values and the relevant calculations were given in Table 3. Koçtürk 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 labour, diesel and electricity used during the production process. On the other hand, non-renewable energy includes petrol, diesel, electricity, chemicals, fertilizers, machinery, while renewable energy consists of human and animal labour (Mandal et al. 2002; Singh et al. 2003)”. Energy inputs of chestnut fruit production, in the form of direct and direct, as well as renewable and non-renewable energy were given in Table 4. Economic analysis of chestnut fruit production was given in Table 5.

Table 2 Energy analysis in chestnut fruit production
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Table 3 Energy analysis indicators in chestnut fruit production
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Table 4 Energy inputs in the forms of energy for chestnut fruit production
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Table 5 Net return and benefit-cost ratio of the chestnut fruit production
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Results and Discussion

The average amount of chestnut fruit produced per hectare for 2016 production season was calculated as 6000 kg. As it can be evaluated in Table 2, energy inputs in chestnut fruit production were as follows, respectively: 3175.20 MJ ha−1 (51.53%) chemical fertilizers energy, 1621.51 MJ ha−1 (26.32%) human labour energy, 675 MJ ha−1 (10.95%) petrol/gasoline energy, 450 MJ ha−1 (7.30%) farmyard manure energy, 213.11 MJ ha−1 (3.46%) animal labour energy and 27 MJ ha−1 (0.44%) transportation energy. Total input energy was calculated as 6161.82 MJ ha−1. Production output chestnut fruit yield and output energy were calculated as 6000 kg ha−1 and 70,800 MJ ha−1. In terms of chestnut fruit production, it is noteworthy that chemical fertilizers, human labour energy and petrol/gasoline energy were the highest input.

Similarly, in previous studies related to fruit studies, Demircan et al. (2006) calculated that the fertilizer application energy had the biggest share by 45.35% in sweet cherry, Banaeian and Zangeneh (2011) calculated that fertilizer application energy had the biggest share by 41.50% in walnut, Qasemi-Kordkheili et al. (2013) calculated that fertilizer application energy had the biggest share by 36.93% in nectarine, Mohammadi et al. (2010) calculated that fertilizer application energy had the biggest share by 47.23% in kiwifruit, Canakcı (2010) calculated that fertilizer application energy had the biggest share by 57.40 in pomegranate etc. The results evaluated that 827.30 h of human labour energy is required per hectare of chestnut fruit production. Human labour energy and petrol/gasoline energy were used for farm operations and pruning motor.

Chestnut fruit yield, energy input, energy output, energy output/input ratio, specific energy, energy productivity and net energy in chestnut fruit production were calculated as 6000 kg ha−1, 6161.82 MJ ha−1, 70,800 MJ ha−1, 11.49, 1.02 MJ kg−1, 0.97 kg MJ−1 and 64,638.18 MJ ha−1, respectively (Table 3). As specific energy, 1.02 MJ of energy is obtained of 1 kg chestnut fruit. In previous fruit studies, Gezer et al. (2003) calculated (apricot) energy use efficiency as 3.37, Göktolga et al. (2006) calculated (peach) energy use efficiency as 0.93, Esengün et al. (2007) calculated (dry apricot) energy use efficiency as 1.24 and 1.31, Demircan et al. (2006) calculated (sweet cherry) energy use efficiency as 1.23, Kızılaslan (2009) calculated (cherry) energy use efficiency as 0.96, Canakcı (2010) calculated (pomegranate) energy use efficiency as 1.25–1.94, Beigi et al. (2016) calculated (almond) energy use efficiency as 0.62, 1.12 and 0.81, Gökdoğan and Erdoğan (2017) calculated (organic olive) energy use efficiency as 2.72, Baran et al. (2017a) calculated (walnut) energy use efficiency as 0.61 and Baran et al. (2017b) calculated (plum) energy use efficiency as 1.39.

The distribution of inputs was used for the production of chestnut fruit, in accordance to direct, indirect, renewable and non-renewable energy groups is given in Table 4. The consumed total energy input in chestnut fruit production could be classified as 40.73% direct, 59.27% indirect, 37.08% renewable and 62.92% non-renewable. In this study, non-renewable energy sources composed 62.92% (3877.20 MJ ha−1) of the total energy input, which was higher than that of the renewable resources 37.08% (2284.62 MJ ha−1). Energy use efficiency was increased, because usage of farmyard manure were used instead of chemical fertilizers for energy equivalent of chemicals fertilizers is high. Similarly, fruit studies on lemon, mandarin, orange (Ozkan et al. 2004a), sweet cherry (Demircan et al. 2006), kiwifruit (Mohammadi et al. 2010), pomegranate (Çanakcı 2010), walnut (Banaeian and Zangeneh 2011), nectarine (Qasemi-Kordkheili et al. 2013), quince (Gündoğmuş 2013), plum (Baran et al. 2017b) etc. resulted where the ratio of non-renewable energy was higher than the ratio of renewable energy.

Economic analysis of chestnut fruit production was given in Table 5. The total cost of chestnut fruit production per kg was explained in Turkish Lira (TL), which was equal to 0.33 US dollars (US$) in 2016 (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) fom the gross value of production”. The gross return was calculated by subtracting the variable cost of production per hectare (14,869.60 TL ha−1) from the gross value of production (60,000 TL ha−1) and was calculated as 45,130.40 TL ha−1. In the evaluation study, the profit margin per kg of chestnut fruit (TL kg−1) was calculated as 6.97. According to evaluation results, the net return in the chestnut fruit production was at a satisfying level. It can be explained that the net return of 3.29 TL was obtained per 1 TL invested and was a cost effective business for 2016 season of chestnut fruit production. In previous fruit studies, Demircan et al. (2006) calculated (sweet cherry) benefit-cost ratio as 2.53, Esengün et al. (2007) calculated (dry apricot) benefit-cost ratio as 1.11 and 1.19, Beigi et al. (2016) calculated (almond) benefit-cost ratio as 4.19, 6.30 and 4.76, Baran et al. (2017a) calculated (walnut) benefit-cost ratio as 1.88 and Mohammadi et al. (2010) calculated (kiwifruit) benefit-cost ratio as 1.94.

In this evaluation study, the energy use efficiency analysis of chestnut fruit production was done. According to the evaluation results, chestnut fruit production is a profitable activity in terms of energy use efficiency analysis (11.49) and economic analysis (3.29). Energy use efficiency analysis was calculated by dividing the energy output/energy input ratio. According to the given economic analysis results, the net return from chestnut fruit production, when compared to the total cost of production in the chestnut fruit producers was at a satisfactory level. The benefit-cost ratio was calculated by dividing the gross value of production by the total cost of production per hectare, resulting in 3.29. Chestnut fruit production is a cost effective business based on 2016 production season. In order to increase the profit margin and thus increase the revenue of manufacturers, it is important to establish organizations such as producer cooperatives and increase industrial establishments particularly based on agriculture (such as candied chestnut processing factory).

The use of chemical fertilizers, especially nitrogen was the most energy consuming input in chestnut fruit production (39.83%). The result indicated that most of the energy was consumed in the form of non-renewable energy, such as chemical fertilizers 51.53% of the total energy input. Demircan et al. (2006) reported that, “accurate fertilization management, taking the amount and frequency of fertilization (especially nitrogen) into account”. Increasing the usage of renewable energy sources can make possible to supply sustainable energy development aims (Rafiee et al. 2010; Barut et al. 2011). Optimization of energy using in agricultural systems is arrived in two ways: an increase in productivity with the present level of energy inputs or conserving energy without affecting the productivity. Energy management becomes more important when the energy required should be economical, sustainable and productive (Gündoğmuş 2013). It is obvious that by expecting to these suggestions yield and energy benefit-cost ratio will increase in chestnut fruit production.