Dynamics and Sustainability of Urban Agriculture: Examples from Sub-Saharan Africa

Sustainability Science, Volume 5, Number 1, 2010, 69-78

Pay Drechsel and Stefan Dongus

Urban agriculture can have many different expressions, varying from backyard gardening to poultry and livestock farming. This article focuses on crop production on larger open spaces in cities of sub-Saharan Africa (SSA) and investigates the sustainability and dynamics of this type of land use, which is common on undeveloped plots particularly in lowlands, such as in inland valleys, or along urban streams or drains. An adapted version of the Framework for Evaluating Sustainable Land Management (FESLM) developed by the Food and Agriculture Organization of the United Nations (FAO) was used to assess the sustainability of urban agriculture. As an example for dynamics, the spatio-temporal changes of open-space agriculture in Dar es Salaam, Tanzania, are analyzed for the period from 1992 to 2005, and compared with data from other cities. Crop production on urban open spaces appears as a market-driven, highly productive and profitable phenomenon. However, it is often constrained by tenure insecurity and non-agricultural land demands. Also, the common use of polluted water limits the official support of irrigated urban farming. However, despite these constraints, the phenomenon of urban farming appears persistent and resilient to its changing environment, although individual farmers might have to shift to other sites when their plots are needed for construction. Open-space vegetable production in urban areas is a dynamic, viable and largely sustainable livelihood strategy, especially for poor urban dwellers. Spatio-temporal analysis shows that it is not a short-lived or transitional phenomenon—probably as long as it can maintain its comparative market advantage. However, its informal nature and resulting lack of political recognition need to be addressed.”

Managing Tricky Decentralised Competencies: Case Study of a Participatory Modelling Experiment on Land Use in the Lake Guiers Area in Northern Senegal

Sustainability Science, Volume 4, Number 2, 2009, 243-261

Grégoire Leclerc, Alassane Bah, Bruno Barbier, Laurence Boutinot, Aurélie Botta, William’s Daré, Ibrahima Diop Gaye, Christine Fourage, Géraud Magrin and Mame Arame Soumare, et al.

“We describe an action-research project whose objective was to help stakeholders at different organisational levels achieve sustainable land management by developing mediation models and tools. We chose to test a specific approach called companion modelling in the framework of a multidisciplinary research partnership and a formal local partnership (a ‘users committee’) involving an array of stakeholders at different organisational levels. The study area covers 10,000 km2 of agro-pastoral land around Lake Guiers in northern Senegal. We conducted studies to update the knowledge base of the area and organised six field workshops that clearly revealed three important tool functions to support decision-making on land use at different scales, i.e. understanding maps, monitoring and evaluating land tenure, and foreseeing changes in land use. We found that a toolbox approach was the best way to implement the three functions and overcome the constraints faced by the research team and those linked to the timing of the project. Therefore, we produced five simple complementary tools aimed at various users: a farm-level optimisation model (for researchers and technical services), a database for land allocations and a discussion tool to assess the impact of land allocation decisions (for the rural council), a paper atlas (for local players) and a regional land use change simulation model (for regional and national planners). Participants were able to work with paper maps, to interpret computer-generated simulations of land use change and understand the strengths and limitations of each. Self-assessment of the research process emphasised the importance of the context and the critical role played by social capital at both the research and the field level, which, in turn, emphasised the need for major improvements in the design and implementation of a quality process for participatory modelling. It turns out that action-research may be an effective way to undertake sustainability science.”

Structuring Sustainability Science

Sustainability Science, Published Online 23 August 2010

Anne Jerneck, Lennart Olsson, Barry Ness, Stefan Anderberg, Matthias Baier, Eric Clark, Thomas Hickler, Alf Hornborg, Annica Kronsell and Eva Lövbrand, et al.

“It is urgent in science and society to address climate change and other sustainability challenges such as biodiversity loss, deforestation, depletion of marine fish stocks, global ill-health, land degradation, land use change and water scarcity. Sustainability science (SS) is an attempt to bridge the natural and social sciences for seeking creative solutions to these complex challenges. In this article, we propose a research agenda that advances the methodological and theoretical understanding of what SS can be, how it can be pursued and what it can contribute. The key focus is on knowledge structuring. For that purpose, we designed a generic research platform organised as a three-dimensional matrix comprising three components: core themes (scientific understanding, sustainability goals, sustainability pathways); cross-cutting critical and problem-solving approaches; and any combination of the sustainability challenges above. As an example, we insert four sustainability challenges into the matrix (biodiversity loss, climate change, land use changes, water scarcity). Based on the matrix with the four challenges, we discuss three issues for advancing theory and methodology in SS: how new synergies across natural and social sciences can be created; how integrated theories for understanding and responding to complex sustainability issues can be developed; and how theories and concepts in economics, gender studies, geography, political science and sociology can be applied in SS. The generic research platform serves to structure and create new knowledge in SS and is a tool for exploring any set of sustainability challenges. The combined critical and problem-solving approach is essential.”

New Perspectives on the Energy Return on (Energy) Investment (EROI) of Corn Ethanol

Environment, Development and Sustainability, published online 11 July 2010

David J. Murphy, Charles A. S. Hall, and Bobby Powers

“Research on corn ethanol is overly focused on whether corn ethanol is a net energy yielder and, consequently, has missed some other fundamental issues, including (1) whether there is significant error associated with current estimates of the EROI of corn ethanol, (2) whether there is significant spatial variability in the EROI of corn ethanol production, (3) whether yield increases will translate linearly to increases in EROI, (4) the extent to which assumptions about co-product credits impact the EROI of corn ethanol, and (5) how much of the ethanol production from biorefineries is net energy. We address all of these concerns in this research by: (1) performing a meta-error analysis of the calculation of EROI, (2) calculating the EROI for 1,287 counties across the United States, and (3) performing a sensitivity analysis for the values of both yield and co-products within the calculation of EROI. Our results show that the average EROI calculated from the meta-error analysis was 1.07 ± 0.2, meaning that we are unable to assert whether the EROI of corn ethanol is greater than one. The average EROI calculated across 1,287 counties in our spatial analysis was 1.01, indicating that the literature tended to use optimal values for energy inputs and outputs compared to the average conditions across the Unites States. Increases in yield had a trivial impact on EROI, while co-product credits had a large impact on EROI. Based on our results from the spatial analysis and the location of biorefineries across the United States, we conclude that the net energy supplied to society by ethanol is only 0.8% of that supplied from gasoline. Recent work indicates that only energy sources extracted at EROIs of 3:1 or greater have the requisite net energy to sustain the infrastructure of the transportation system of the United States. In light of this work, we conclude that production of corn ethanol within the United States is unsustainable and requires energy subsidies from the larger oil economy.”

Impact Assessment of the European Biofuel Directive on Land Use and Biodiversity

Journal of Environmental Management, Volume 91, June 2010

Fritz Hellmann and Peter H Verburg

“This paper presents an assessment of the potential impact of the EUs biofuel directive on European land use and biodiversity. In a spatially explicit analysis, it is determined which ecologically valuable land use types are likely to be directly replaced by biofuel crops. In addition, it is determined which land use types may be indirectly replaced by biofuel crops through competition over land between biofuel and food crops. Four scenarios of land use change are analyzed for the period 2000-2030 while for each scenario two policy variants are analyzed respectively with and without implementation of the biofuel directive. The results indicate that the area of semi natural vegetation, forest and High Nature Value farmland directly replaced by biofuel crops is small in all scenarios and differs little between policy variants. The direct effects of the directive on European land use and biodiversity therefore are relatively minor. The indirect effects of the directive on European land use and biodiversity are much larger than its direct effects. The area semi natural vegetation is found to be 3-8% smaller in policy variants with the directive as compared to policy variants without the directive. In contrast, little difference is found between the policy variants with respect to the forest area. The results of this study show that the expected indirect effects of the directive on biodiversity are much greater than its direct effects. This suggests that indirect effects need to be taken explicitly into account in assessing the environmental effects of biofuel crop cultivation and designing sustainable pathways for implementing biofuel policies.”

Concentrating Solar Power in China and India: A Spatial Analysis of Technical Potential and the Cost of Deployment

Center for Global Development, Working Paper 219

Kevin Ummel

“Coal power generation in China and India could double and triple, respectively, over the next 20 years, which would increase exposure to fuel price volatility, exacerbate local air pollution, and hasten global climate change. Moving to concentrating solar power (CSP), a growing source of utility-scale, pollution-free electricity, would help alleviate these problems, but its potential in Asia remains largely unexamined. In this working paper, Kevin Ummel uses high-resolution spatial data to identify areas suitable for CSP and estimates power generation and cost under various land-use scenarios.

“Total CSP potential in China is at least 16 times greater than current coal power output; in India, it is at least 3 times greater. A CSP expansion program could provide 20 percent of electricity in both countries by midcentury. Under conservative assumptions, the program will require subsidies of $340 billion in present dollars. Estimated costs are especially sensitive to the assumed rate of technological learning, making it especially important to form committed public policy and financing to reduce investment risk, encourage the expansion of manufacturing capacity, and achieve long-term cost reductions.”

Spatial Analysis of Biomass Supply: Economic and Environmental Impacts

ASA, CSSA, and SSSA International Annual Meetings
31 October – 03 November 2010
Long Beach, California USA

David Archer

“The EPIC simulation model is used with SSURGO soils, field location information, and a transportation cost model to analyze potential biomass supply for a West Central MN bioenergy plant. The simulation shows the relationship between biomass price, locations of where biomass production is profitable, and impacts on economic optimum cropping practices. Results show expansion of production away from the bioenergy plant as biomass price increases. Also, increasing biomass price tends to increase harvest intensity and change the optimum crop rotation near the bioenergy plant. These changes have important implications for the environmental impacts of biomass harvest, since changes in harvest intensity and crop rotation can have substantial effects of soil erosion, soil carbon, and nutrient and pesticide runoff and leaching.”