Energy Efficiency and Ecological Footprint Analysis of Tomato Production Farms in Asadabd County of Iran

Introduction: In modernization era, high consumption level and improper use of external agricultural inputs (fertilizers, pesticides, and fuels), particularly in developing countries, have resulted in different consequences such as climate change, water pollution, or natural resource depletion. For example, agriculture is responsible for approximately 20 percent of greenhouse gas emissions. Iran is the largest emitter of greenhouse gases in the Middle East. Hence, over recent years, evaluating environmental capacities and studying environmental impacts of agricultural production have increased. One important facet of studying agricultural systems is to evaluate their sustainability. One of the most important quantitative models of measuring sustainability is the ecological footprint known as an accounting metric, which assesses humanity’s pressure on natural resources and situates consumption levels within the Earth’s ecological limits. Due to the increase in population and demand for agricultural products, creating new forms of energy in the agricultural sector and improper use of inputs, this economic sector has become an energy consuming sector. So far, various studies have been conducted to measure energy efficiency in the agricultural sector. Despite the fact that a large proportion of tomato production in the Hamedan province of Iran is related to Asadabad County, there seems to be no clear attention to sustainability status of agricultural operations. Therefore, this study aimed at studying the ecological footprint and energy efficiency to assess sustainability of the tomato production in Asadabad as a main tomato producer in the west Iran. The specific objectives of the study included: (1) Describing the demographic and technical profile of tomato producers, (2) Evaluating the energy efficiency regarding the inputs and products, and (3) Estimating the direct and indirect ecological footprint of tomato production to identify the most crucial production inputs in terms of pollutant emissions.
Materials and Methods: The ecological footprint (EF) has become a popular indicator since it was first introduced in a publication in the 1990s. Based on energy consumption, the place-oriented method was used, and therefore, consumption-based EF as well as direct and indirect EF were calculated. Global hectares approach was used to measure the ecological footprint unit. In addition, according to energy input and output resulting from the consumption of inputs and from the products, energy efficiency was estimated. The study was conducted in a descriptive-survey research method using a questionnaire, and a sample of 210 tomato producers was randomly selected. To estimate the energy consumption, equivalence factors ( were used to estimate the amount of energy produced from each of the inputs and outputs. The ecological footprint was defined as the sum of real and virtual lands directly or indirectly related to crop production, and were required to absorb CO₂ emitted by that production, which was expressed in Equation (1), where  showed the land occupied over time by croplands, built area, pastures and forests for crop production, and was calculated by Equation (2), in which  represented the amount of occupied land with type a (cropland, forest, pasture, built area),  equaled one while  resembled the equivalence factor for land type a,  was equal to 2/2.  showed the amount of forest required for absorbing CO₂ emitted during the product's lifecycle, which was calculated by Equation (3), where  represented the amount of energy consumption by inputs in GJ ha^-1,  was the ability of a hectare of forest land to absorb carbon released from energy equal to 71 GJ petroleum:      
Results and Discussion: Results of the EF analysis showed that the  was estimated at 1/42 gha and the consumption-based EF was measured to be 7.57 gha. Accordingly, an area of 1/42 ha of productive land would be needed to meet the challenge of bio-capacity reduction. The total energy consumption was more than the ecological capacity of the required land to produce tomato per hectare, indicating the unsustainability of potato production regarding the environmental impacts. Energy efficiency and productivity indices from the ratio of energy output and tomato yield to energy input resulted from inputs, especially electricity with 38.9 percent, nitrogen fertilizer with 26.9 percent and gasoline with 15.2 percent, a total of 81 percent, were calculated equal to 0.34 and 0.42 MJ, respectively. In the  and the consumption-based EF, the highest share belonged to electricity, nitrogen fertilizer, and gasoline, respectively. Thus, due to the emission of pollutants, because of irregular and unprincipled consumption of inputs, tomato production in Asadabad County was found to be ecologically unsustainable.  
Conclusions: The study findings implied that lower use of electricity, fertilizers and gasoline could play a significant role in mitigating the environmental impacts of tomato production. Due to the water shortage in the studied region, and high consumption of electricity for electric irrigation pumps, strategies such as using high efficiency pumps, regular technical repair of equipment, use of ponds and tanks to store water, allocating low-interest facilities to farmers to use modern irrigation methods and encouraging them to integrate their farms are recommended. About the high consumption level of chemical fertilizers, strategies such as increase in the use of organic and compost fertilizers, compliance with the permissible limit, and also using non-chemical methods such as biological control to prevent pests’ resistance to chemical toxins are recommended as well. Regarding the high consumption level of gasoline, use of combined and advanced machinery to reduce the plowing operations, and technical inspection of agricultural machinery for lower and optimal fuel consumption are also recommended.