Research Journal of Applied Sciences, Engineering and Technology 3(3): 194-201, 2011 ISSN: 2040-7467 © Maxwell Scientific Organization, 2011 Received: January 06, 2011 Accepted: February 07, 2011 Published: March 30, 2011 Corresponding Author: Narges Banaeian, Department of Agricultural Machinery, Faculty of Agricultural Engineering and Technology, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran. Tel: +98-261-2801011/+98-918-911-0115; Fax: +98-261-2808138 194 Modeling Energy Flow and Economic Analysis for Walnut Production in Iran Narges Banaeian and Morteza Zangeneh Department of Agricultural Machinery Engineering, Faculty of Agricultural Engineering and Technology, School of Agriculture and Natural Resources, University of Tehran, Karaj: Iran Abstract: The aims of this study were to determine energy use pattern, to obtain relationship between energy inputs and yield, and to make an economical analysis in walnut orchards in Hamadan, Iran. Required data were obtained from 47 walnut orchards based on random sampling method. The results indicate that walnut production consumed a total energy of 15196.1 MJ/ha where chemical fertilizers with about 41% were the major energy consumer. Energy use efficiency, energy productivity and specific energy of walnut production were 2.9, 0.3 and 3.4 MJ/kg, respectively. Econometric estimation results revealed that energy inputs of human labor, farmyard manure, chemical fertilizers, water for irrigation and transformation contributed significantly to the yield. The results of sensitivity analysis of the energy inputs showed that the Marginal Physical Productivity (MPP) value of human labor was the highest, followed by farmyard manure and water for irrigation energy inputs, respectively. The results also showed that direct, indirect and renewable and non- renewable, energy forms had a positive impact on output level and the MPP value of direct and renewable energy were higher. The benefit to cost ratio, mean net return and productivity from walnut production was obtained as 2.1, 2043.7 $/ha and 0.3 kg/$, respectively. Key words: Economic analysis, input-output energy, sensitivity, walnut orchards INTRODUCTION Iran is ranked fourth in the world after USA, China and Turkey in walnut production (Anonymous, 2008). The production of walnut was about 290,000 tons per year in Iran and the harvested land area was 185,000 ha in 2008. Hamadan province is the first producer of walnut production per hectare and provided one of the most desirable walnuts of world (Anonymous, 2009). Walnuts do not only provide healthy fatty acids and high calorie, they are also rich in vitamins and minerals which help us to stay healthy. It includes potassium, magnesium, phosphorus, iron, calcium, zinc, copper, vitamin B9, B6, E, A and etc. (Koyuncu et al., 2004). The amount of energy used in agricultural production, processing and distribution is significantly high. Sufficient supply of the right amount of energy and its effective and efficient use are necessary for an improved agricultural production. It has been realized that crop yields and food supplies are directly linked to energy (Stout, 1990). In the developed countries, increase in the crop yields was mainly due to increase in the commercial (but often subsidized) energy inputs in addition to improved crop varieties (Faidley, 1992). Calculating energy inputs of agricultural production is more difficult than the industry sector due to the high number of factors affecting the agricultural production (Yaldiz et al., 1993). The main objective in agricultural production is to increase yield and decrease costs. In this respect, the energy budget is important. Energy budget is the numerical comparison of the relationship between input and output of a system in terms of energy units (Gezer et al., 2003). In general, increases in the agricultural production on a sustainable basis and at a competitive cost are vital to improve the farmer’s economic condition (De et al., 2001). Although many experimental works have been conducted on energy use in agriculture, there is no study on the energy and economical analysis of walnut production. Rafiee et al. (2010) studied energy use for apple production in Tehran province and Mohammadi et al. (2010) investigated energy inputs and crop yield relationship to develop and estimate an econometric model for kiwifruit production in Mazandaran province in Iran. The aims of this research were to determine the energy use efficiency per hectare for the walnut production, do a sensitivity analysis on energy inputs for walnut yield and compare input energy use with input costs. This study wants to reveal relationship between energy inputs and yield by developing mathematical models based on walnut orchards in Hamadan province of Iran.