Evaluation of environmental impacts for wheat Agroecosystems of Iran by using Life Cycle Assessment methodology

Life cycle assessment (LCA) is a methodology for assessing the environmental impacts associated with a product, by identifying, quantifying and evaluating the resources consumed, and all emissions and wastes released into the environment. This study examined the environmental impacts for irrigated and rainfed wheat agroecosystems of Iran based on nitrogen levels by using LCA methodology during year of 2013. Four steps such as goal definition and scoping, inventory analysis, life cycle impact assessment and integration and interpretation were considered based on ISO 14040 methods. Impact categories were global warming, acidification, terrestrial eutrpphication and aquatic eutrpphication. After normalization and weighting of the indicator values, environmental impacts (EcoX) was calculated. The results showed that the highest yield for irrigated and rainfed wheat agroecosystems were recorded with 3.8 and 2.8 t.ha-1 by using 200-220 and 50-60 kg N.ha, respectively. In irrigated wheat agroecosystem, the maximum global warming, acidification, aquatic eutrophication and terrestrial eutrophication were observed in >220 kg N.ha-1 with 889.61 CO2 equiv./t grain, 1.53 SO2 equiv./t grain, 2.41 PO4 equiv./t grain and 1.11 NOx equiv./t grain, respectively. In rainfed wheat agroecosystem, these values calculated in >60 kg N.ha-1 with 937.73 CO2 equiv./t grain, 3.03 SO2 equiv./t grain, 3.74 PO4 equiv./t grain and 5.05 NOx equiv./t grain, respectively. EcoX ranges for irrigated and rainfed agroecosystems were calculated with 0.47-0.55 and 0.34-0.43 per one ton grain, respectively.