Comparison of Environmental Impacts for Rice (Oryza sativa L.) Agroecosystems in the First and Second Planting Patters by using Life Cycle Assessment (Case Study: Sari County)

Life Cycle Assessment (LCA) is the most developed and the worldwide accepted tool for environmental comparison of products and services. Environmental Life Cycle Assessments (LCA) studies the environmental aspects and potential impacts of a product from ‘cradle-to-grave’ (Brentrup et al., 2004b).  Compared to other environmental impact assessment methods, LCA incorporates all the various stages of an agricultural production supply chain. This method is the only environmental assessment methodology which has been standardized. Life cycle assessment (LCA) is a methodology to assess all environmental impacts associated within a product/service by a accounting and evaluating its resource consumption and emission to environment (Nemecek et al., 2011).
Rice (Oryza sativa L.) is one of the most important crops (Chabra et al., 2006). The aim of this study was to determine environmental impacts of rice production systems in the first and second planting patterns by using Life Cycle Assessment. This study evaluated the environmental impacts of rice production systems in the first and second planting patterns by using life cycle assessment (LCA) methodology, mean consumed inputs per one hectare in rice agroecosystems of Sari province were determined during 2014. The data were collected from 105 paddy farmers by interviewing the farmers using questionnaire. Four steps including goal definition and scoping (D & S), inventory analysis (IA), life cycle impact assessment (LCIA) and integration & interpretation (I & I) were considered based on ISO (International Organization for Standardization) 14040 methods. Global warming, acidification and aquatic and terrestrial eutrophication were considered as three important impact categories. Functional unit of rice agroecosystems was considered as one tone paddy. Cronbach's alpha coefficient was calculated as a tool for the reliability assessment. Cronbach's alpha coefficient for questionnaire was calculated equal to α=%82. The results showed that the highest global warming potential between two cropping patterns was related to the second pattern with 840.36 kg CO2-equiv. one ton paddy. In the second planting pattern, pollutant emissions in global warming category CO2, CH4 and N2O calculated 402.82, 0.85 and 436.70 kg CO2-equiv. one ton paddy per  ha-1, respectively. In the second planting pattern, pollutant emissions in acidification category such as NH3, NOx and SO2 were computed 0.721, 0.225 and 0.541 kg SO2-equiv. one ton paddy per ha-1, respectively. The maximum eutrophication potential in aquatic and terrestrial environments was belonged to the second planting pattern with 2.07 kg PO4-equiv. one ton paddy per ha and 2.48 kg NOx-equiv. one ton paddy per ha -1, respectively. The maximum environmental indicator for rice production systems in the second planting pattern were computed 0.39 EcoX one ton paddy. LCA is an appropriate method to quantify the impact of utilized agricultural inputs and different managements on environment. The highest environmental impacts of rice production systems in the first and second planting patterns by using life cycle assessment (LCA) methodology was related to aquatic eutrophication category. Therefore, it can be concluded that applying ecological principles such as reduced tillage and organic fertilizer as sustainable approaches were considered for management of rice agroecosystems especially in the second planting pattern.