Dynamics of sustainability in integrated agriculture : aquaculture systems in the Mekong Delta
Key words: Mekong Delta; IAA; ECOPATH; Nutmon; LCA; environmental impact; sustainability In the Mekong Delta (MD), intensification and modernization of crop, fish and livestock production causes concern about sustainable use of natural resources. The objectives of this research were to understand the driving forces for changes in farming practices, and to quantify and evaluate agro-ecological attributes, nutrient balances, and environmental impacts in Integrated Agriculture-Aquaculture (IAA) systems. Three districts differing in cropping patterns and intensity of fish culture were selected for this study: a rice-based and high input fish system (R-HF) in O Mon district, a rice-based and medium input fish system (R-MF) in Tam Binh district, and an orchard-based and low input fish system (O-LF) in Cai Be district. Two surveys (2002 and 2004), covering 90 households, were carried out to analyse drivers for changes in IAA systems. Another survey was conducted at the end of the study to evaluate the awareness of farmers on sustainability issues. One extra survey (2005) was conducted to analyse the impact of the Avian Influenza (AI) outbreak on livelihoods. Eleven farms were selected for detailed monitoring of inputs, outputs and internal bio-resource flows of rice, fruits, vegetables, pigs, poultry, and fish over a period of two years (2002-2004). The agro-ecological attributes of the selected farms were quantified using ECOPATH. The adapted Nutmon (Nutmon-Asia) model was used to quantify soil nutrient balances. A detailed cradle-to-farm-gate life cycle assessment (LCA) was performed to assess the integral environmental impact of IAA farming. The policy of economic liberalization, introduction of modern rice varieties, increasing market demands, and natural disasters were main drivers for changes in IAA farming systems. Well-off farmers tended to intensify their farming practices, whereas the poorer farmers tended towards diversification to safeguard their livelihoods and avoid risks. The ECOPATH, Nutmon-Asia and LCA modelling approaches proved complementary in analysing agro-ecological performances, identifying ecological sustainability issues, and quantifying sustainability indicators at farm and farming system level. The 19 agro-ecological attributes, quantified by ECOPATH, were combined into four sustainability factors: Productivity-Efficiency, Diversity, Maturity, and Aquaculture Integration. Rice-based farms (R-HF and R-MF) were more efficient and productive than the orchard-based farms (O-LF) and recycled nitrogen more intensively within the farm. Productivity-Efficiency was directly related to sustainability of farms. A high farm output in relation to external input use could be achieved both by farms with low external input use and by farms with a relatively high external input use. Soil nutrient balances are important indicators of nutrient use efficiency of farming systems. The Nutmon-Asia results showed that all farms in the three systems had positive nutrient balances of nitrogen, phosphorus and potassium. A negative potassium balance was found in the rice fields of all three systems. Improvements of the nutrient balances can start by lowering the quantity of fertilizers applied. LCA was used to quantify the use of resources and environmental emissions per kcal and kg farm product, and per farm. Land use and energy use per kcal farm product did not differ among the three systems. However, global warming potential (GWP), eutrophication potential (EP), and acidification potential (AP) per kcal farm product were 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 a higher land use, energy use, GWP, EP, and AP than the average kg of fish produced in the other two systems. 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 CH4 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. The IAA farmers profited from their flexibility and diversity in farming activities during the period of the AI outbreaks. Farmers were more concerned about social than economic and ecological sustainability issues. The O-LF system scored less on some of the ecological sustainability issues and the O-LF farmers were also less aware of the importance of these issues. Intensification of farming practices will continue. For enhancing nutrient recycling on the farms, emphasis should be on maintaining traditional sustainable farm practices, such as re-use of crop and animal wastes within the farm and integrating fish ponds and using of pond sediment as crop fertilizer. Research, development and extension services should pay attention to strategies for increasing resilience of IAA systems in the MD, by focusing on reducing external farm inputs and improving farm nutrient management. In the MD the demands for animal protein will increase. Stimulation of aquaculture seems more appropriate than stimulation of pig and poultry production, seeing that the environmental impacts per kg protein for fish were lower than for pigs and poultry.
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| Format: | Doctoral thesis biblioteca |
| Language: | English |
| Subjects: | animal production, aquaculture, farming systems, integrated farming systems, sustainability, sustainable agriculture, vietnam, aquacultuur, bedrijfssystemen, dierlijke productie, duurzaamheid (sustainability), duurzame landbouw, geïntegreerde bedrijfssystemen, |
| Online Access: | https://research.wur.nl/en/publications/dynamics-of-sustainability-in-integrated-agriculture-aquaculture- |
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