Life cycle assessment of food production in integrated agriculture–aquaculture systems of the Mekong Delta

Abstract

This study evaluated the environmental impact of integrated agriculture–aquaculture (IAA) farming systems in the Mekong Delta that differ in types of aquaculture intensification. Daily inputs and outputs for rice, fruits, vegetables, pigs, poultry, and fish were collected on 11 farms over a period of two years: three farms in a rice-based and high input fish system (R-HF); four in a rice-based and medium input fish system (R-MF); and four in an orchard-based and low input fish system (O-LF). For each farm, a detailed cradle-to-farm-gate life cycle assessment was performed. Kcal as functional unit (FU) enabled a comparison of the integral environmental impact among farming systems, and identification of major processes influencing the outcome of an impact category. kg product as FU enabled evaluation of impacts for the individual products of IAA farms. The environmental impact was also quantified for each farm as a whole to identify which farm components explained the majority of the environmental impact in absolute terms. Land use per kcal farm product did not differ among the three farming systems. Global warming potential (GWP), energy use and eutrophication potential (EP) per kcal farm product tended to be higher, whereas acidification potential (AP) was higher, in O-LF than in R-HF and R-MF, mainly due to the low calorie content of the two main products, fruits and vegetables, and the small fish yield in O-LF. One kg of fish produced in O-LF farms showed 28% higher land use, 35% higher energy use, 54% higher GWP, 45% higher EP, and 52% higher AP than the average kg of fish produced in the other two systems, due to the pond management system and small fish yield in O-LF. For each impact category, the impact per kg pig and poultry protein were on average 1.6–1.8 times higher than the impacts per kg fish protein. Overall, rice and pigs were the main contributors to the environmental impact of food production in the MD. Excessive and inefficient use of fertilizers, and CH 4 emission from the paddy fields contributed most to the environmental impact in rice production, whereas the use of external feeds contributed most to the impact in pigs.