Ecological– Economic Efficiency for Alfalfa (Medicago sativa L.) and Corn Silage (Zea mays L.) Production Systems: Maragheh– Bonab Plain, East Azerbaijan Province

Agriculture development heavily relies on chemical inputs such as synthetic fertilizers, pesticides, fossil fuels and other energy-intensive inputs. This development is having a serious impact on public health and the environment. Therefore, efficient use of resources is a primary and most vital implications for sustainable agriculture development. Sustainability indices are quantitative values that can be used to evaluate the efficiency and quality of agroecosystems and are useful tools for making suitable decisions in its management. These including energy flow indices, global warming potential (GWP), economic indices, environmental impact quotient (EIQ) of pesticides, efficiency of land, water and fertilizers use and etc. Alfalfa and corn silage as the main source of feed for livestock, have a notable area in the cropping pattern of Maragheh-Bonab plain. Therefore, evaluation of sustainability for these crops will help the sustainable management of agroecosystems in the study area. The present study was conducted to: (a) determine energy efficiency and global warming potential; (b) determine the environmental impacts of pesticides; (c) assess input use efficiency and; (d) economic analysis of alfalfa and corn silage production systems in East Azerbaijan province of Iran. In the present study, the sustainability of alfalfa and corn silage production systems lies in the Maragheh-Bonab plain in southern East Azerbaijan province in northwestern Iran were evaluated using quantitative indices such as energy efficiency and productivity, greenhouse gas (GHG) emission; economic indicators; pesticide risk (field environmental impact—FEIQ); tillage impact (TI); fertilizer, labour, land and water use efficiency, and the eco-efficiency index. For this purpose, data was collected from 110 farmers by survey to determine crop production in the region. Secondary data including climate characteristics and products sale price was obtained from previous studies and organizations such as the Agricultural Ministry of Iran. The results showed that the values of input energy, output energy and net energy in alfalfa production system (48151, 432920 and 384768 Mj.ha-1, respectively) were higher than corn silage production system (35557, 217350 and 181792 Mj.ha-1, respectively). Also, it was observed that the values of energy use efficiency and specific energy of alfalfa (9 and 15.8 MJ.kg−1, respectively) were higher than that of corn silage (6.1 and 4.1 MJ.kg−1, respectively). In terms of economic indices, despite of lower total cost of production in corn silage (1089 $.ha-1), the highest values of gross production value (6447 $.ha-1) and net return (4193 $.ha-1) were related to alfalfa production system. In terms of GWP and EIQ, alfalfa production had the higher values with compared to corn silage production. However, eco-efficiency (ratio of economic value to the environmental impact) values based on of GWP and EIQ was significantly higher for alfalfa (1.75 $.kg -1 CO2eq-1 and 35.3 $.EIQ-1) than corn silage (1.5 $.kg-1 CO2eq-1 and 26 $.EIQ-1). Land production efficiency, economic land production efficiency, irrigation water productivity, economic irrigation water productivity, nitrogen use efficiency, phosphorous use efficiency and potassium use efficiency were 140 kg.ha-1.day-1, 21.5 $.ha-1.day-1, 4.1 kg.m-3, 0.63 $.m-3, 335 kg.kg-1, 1191 kg.kg-1 and 1826 kg.kg-1 in alfalfa production system and 583 kg.ha-1.day-1, 22.9 $.ha-1.day-1, 8 kg.m-3, 0.31 $.m-3, 656 kg.kg-1, 3553 kg.kg-1 and 65525 kg.kg-1 in corn silage production system, respectively. It can be concluded that environmental impacts of pesticides and global warming effect per area in alfalfa production system were higher than corn silage production system. However, in terms of economic indices and energy use efficiency, alfalfa production system was superior to corn silage production system.