Dynamics of sustainability in Integrated Agriculture-Aquaculture systems in the Mekong Delta

152 Pages·2010·0.85 MB·English

Dynamics of sustainability in
Integrated Agriculture-Aquaculture systems
in the Mekong Delta

Le Thanh Phong
Thesis committee

Thesis supervisor:
Prof. dr. ir. A.J. van der Zijpp
Professor of Animal Production Systems
Wageningen University

Thesis co-supervisors:
Dr. ir. H.M.J. Udo
Associate professor, Animal Production Systems Group
Wageningen University

Dr. ir. M.E.F. van Mensvoort
Assistant professor, Land Dynamics Group
Wageningen University

Dr. Le Quang Tri
Vice Rector Can Tho University and Dean College of Agriculture and Applied Biology
Can Tho University, Vietnam

Other members:
Prof. dr. ir. M.W.A. Verstegen, Wageningen University
Prof. dr. Vo Tong Xuan, An Giang University, Vietnam
Dr. M.J.C. Verdegem, Wageningen University
Dr. A.A. van Dam, UNESCO-IHE Institute for Water Education, Delft

This research was conducted under the auspices of the Graduate School of Wageningen
Institute of Animal Sciences (WIAS)
Dynamics of sustainability in Integrated Agriculture-
Aquaculture systems in the Mekong Delta

Le Thanh Phong

Thesis
submitted in fulfillment of the requirements for the degree of doctor
at Wageningen University
by the authority of the Rector Magnificus
Prof. dr. M.J. Kropff,
in the presence of the
Thesis Committee appointed by the Academic Board
to be defended in public
on Tuesday 1 June 2010
at 4 p.m. in the Aula
Phong, L.T.
Dynamics of sustainability in Integrated Agriculture-Aquaculture systems in the
Mekong Delta
PhD Thesis, Wageningen University, Wageningen, The Netherlands (2010).
With references, with summaries in English, Dutch, and Vietnamese.

ISBN: 978-90-8585-662-7
Abstract
Phong, L.T., 2010. Dynamics of sustainability in Integrated Agriculture-Aquaculture
systems in the Mekong Delta. PhD thesis, Wageningen University, The Netherlands.

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 modeling 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 CH emission from the paddy fields contributed most to the
4
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.

Key words: Mekong Delta; IAA; ECOPATH; Nutmon; LCA; environmental impact;
sustainability
Contents

Chapter 1 General introduction 1

Chapter 2 Integrated Agriculture-Aquaculture Systems in the Mekong Delta, 15
Vietnam: an analysis of recent trends

Chapter 3 An agro-ecological evaluation of aquaculture integration into 35
farming systems of the Mekong Delta

Chapter 4 Modeling the soil nutrient balance of Integrated Agriculture-Aquaculture 57
Systems in the Mekong Delta, Vietnam

Chapter 5 Life Cycle Assessment of food production in Integrated Agriculture- 81
Aquaculture Systems of the Mekong Delta

Chapter 6 General discussion 103

Summary 127

Tóm lược 131

Samenvatting 133

Acknowledgements 135

Curriculum Vitae 137

List of publications 139

Training and Supervision Plan 143

Chapter 1
General Introduction
Chapter 1

2