Research & reports

Michael Martin, Elvira Molin · Sustainability · Sweden

This study assessed the environmental impacts of urban vertical hydroponic farming through a life-cycle perspective, applied to a case-study vertical hydroponic farm in Stockholm, Sweden, comparing current performance with potential improvement scenarios. Results showed that growing medium, pots, electricity demand, and transportation of raw materials and product deliveries were the important contributors to environmental impact in this system. Replacing plastic pots with paper pots was found capable of producing large reductions in GHG emissions, acidification impacts, and abiotic resource depletion, and replacing conventional gardening soil with coir as the growing medium also led to large impact reductions. However, the study states that further reducing the system's impacts will require more resource-efficient steps specifically to address impacts from electricity demand, an issue not resolved by the pot and growing-medium substitutions, and identifies potential for more symbiotic exchanges using urban wastes and by-products.

Shailesh Deshpande, Priyanka Verma, Piyush Yadav, Jay Gubbi, P Balamurali · Asian Journal of Geoinformatics · South Africa (Johannesburg)

Land Use Land Cover (LULC) changes in Johannesburg City, South Africa, were analyzed using Landsat imagery from 2000 to 2016. The analysis revealed that impervious surface increased by 57.03% during this period, leading to a 47.8% loss of urban vegetation (grass, tree cover) and urban agricultural land. Additionally, soil and water loss amounted to 16.75%.

Runrid Fox-Kämper · · Global

This book provides insights and examples of how urban space is negotiated, describing urban gardens as "lived places" where social relations, meanings, and a sense of place are developed. To trigger social benefits, it is essential that these sites fulfill more functions than just food growing and leisure. Horticultural practices, such as using pesticides or fertilizers, have a strong influence on the ecological impact of urban gardening; although awareness among gardeners has increased due to training programs in recent decades, this impact persists.

肇 石原, Hajime Ishihara · Institutional Repositories DataBase (IRDB) · Japan (Osaka)

This study analyzed changes in green space components (parks, agricultural land, forests) across Osaka Prefecture, Japan, from 1970 to 2010. While forest area decreased slightly and park area increased, the increase in park area was insufficient to offset the significant reduction in agricultural land. Consequently, the overall green space ratio in Osaka Prefecture showed a declining trend, particularly noticeable in Osaka City and its surrounding areas.

Luca Salvati · · Europe

Land-use change in southern Europe was assessed through a case study of the Athens metropolitan region, Greece, analyzing the spatial distribution of built-up areas, cropland and forests together with demographic and socioeconomic indicators across alternating expansion waves over the past 50 years. Per-capita built-up area was higher during the "dispersed" urbanization wave than the "compact" one, but cropland was the land-use class most vulnerable to urbanization, with a high rate of conversion from forest to cropland — later abandoned and finally developed — observed since the early 1990s. This process was linked to land fragmentation and soil degradation driven by illegal housing and real estate speculation.

Guy M. Robinson, Zhiling Liu · AIMS environmental science · Australia

This paper examines the contradictions between greening and "ungreening" in Adelaide, South Australia, focusing on the city's Park Lands and urban sprawl. It argues that urban sprawl, including recent development on prime farmland, has been antithetical to biodiversity maintenance and greening principles, reducing sustainability capacity. The paper identifies problems such as conflict between biodiversity and protecting residents in bushfire risk areas, stemming from a relaxed attitude towards low-density expansion.

Marzieh Rezaei Qaleh, Hossein Medi, Mahdi Sheybani · Cumhuriyet Science Journal · Iran (Qazvin City)

This study investigated the role of urban agriculture in sustaining the urban environment, using Qazvin City, Iran, as a case study. Qazvin City, historically surrounded by traditional gardens that created a favorable urban environment, is now experiencing the destruction of these garden environments due to development processes, posing a risk of breaking the chain of environmental sustainability. The research, based on content analysis through observation and document study, proposed solutions considering environmental concerns, including preserving old irrigation methods, restoring native plant species, and focusing on existing water resources.

Pay Drechsel, Keraita, Bernard N. · CGSPace A Repository of Agricultural Research Outputs (Consultative Group for International Agricultural Research) · Global

A CGIAR (Consultative Group for International Agricultural Research) perspective piece on food and water challenges at the urban-rural interface amid global urbanization. It states that in low-income countries, investments in waste management and sanitation are not keeping pace with population growth, so the urban "return flow" of waste is not adequately managed. Where polluted water is used for irrigation to feed cities, food safety becomes a crucial component of food security. The piece explicitly states that urban and peri-urban farming systems — often run by the informal sector — are the systems most affected by this resource competition and pollution. It describes CGIAR's Water, Land and Ecosystems (WLE) research program as working at the interface of agriculture and sanitation to address these urbanization-related challenges and opportunities.

Ekaete Francis Asuquo · · Nigeria (Calabar)

The impact of urban expansion on agricultural land in Calabar and its environs, Nigeria, was investigated. A survey of 150 questionnaires and comparative assessment revealed a decrease in agricultural land in the fringes as urban expansion persists and increases. Before 2013, more farmers owned larger plots, but much of this agricultural land has been converted to housing estates, roads, leisure resorts, and schools, indicating that urban expansion has negatively impacted agricultural land, reducing food productivity and leading to farmer unemployment.

H. C. Agada, E. A. Obienusi, Emma E. Ezenwaji · Journal of environment and earth science · Nigeria

This study evaluated urban forestry and housing patterns in Awka metropolis, Anambra State, Nigeria, over a ten-year period (2001-2010). Analysis of land use data using linear regression and correlation coefficients confirmed a significant correlation between housing patterns (urbanization) and the distribution of trees (forestry). The least square regression results indicated that the rate of forest displacement is a direct consequence of increasing structural development in the study area.

Yu Wang · · China (Xi'an City)

This study analyzed the dynamic changes in urban agricultural landscape (arable lands and garden plots) due to urbanization in Chang'an District, Xi'an City, China, using remote sensing, GIS, and FRAG-STAT techniques. Compared to 1999, arable land area decreased and aggregation declined by 2.45% in 2011, while garden plot area increased and aggregation rose by 10.44%. Improved urbanization levels decreased arable land area and increased fragmentation, but correlations with garden plot landscape indexes were insignificant.

Eric Vaz, Marco Paìnho, Peter Nijkamp · European Planning Studies · Europe

This paper presents a spatial analysis integrating agricultural land use data inventories for Portugal with CORINE Land Cover data to assess change in the Algarve region. By overlaying the appropriation of agricultural land for urban use with population and urban data, it focuses on the consequences of specific regulations for the dynamics of land-use change. An integrated assessment of agricultural land loss found that agricultural land was being undermined by the consequences of urban sprawl. Building on this finding, the paper reviews existing decrees supporting sustainable development in the region, provides a qualitative assessment of future roles based on ethical values and economic efficiency, and offers a framework for policymakers regarding trends in the urban/agricultural dichotomy.

Zakir Hussain, Markus Hanisch · Journal of Environmental Planning and Management · India

This paper describes the adaptation of agricultural management practices in the urban periphery of Hyderabad, India, due to structural changes. Based on 120 farmer interviews, the study found that increasing costs for agricultural inputs like labor and land motivated farmers to intensify water, machine, and chemical use, which created problematic environmental impacts. Farmers also adapted by resorting to part-time farming and organizing efforts to share family labor.

Patrick F. Banga · · Zimbabwe

Unsanctioned urban agricultural activities in Emakhandeni High Density Suburb of Bulawayo, Zimbabwe, negatively impact biodiversity. Researchers interviewed 100 people and conducted field visits, finding that the majority of cultivators operate outside existing laws and guidelines. This leads to progressive land degradation, massive deforestation, soil erosion, dried wetlands, lowered water table, and compromised groundwater quality due to pesticides and inorganic fertilizers.

Ruth Stewart, Marcel Korth, Laurenz Langer, Shannon Rafferty, Natalie Rebelo Da Silva, Carina van Rooyen · Environmental Evidence · Global

This is a systematic review protocol — not a completed review — that sets out methods for identifying, appraising and synthesizing evidence on how urban agriculture programs affect food security and nutrition in low- and middle-income countries. It notes urban agriculture is widely promoted as providing the urban poor with food and income while improving the urban environment, but also carries potential disadvantages: use of wastewater can contaminate produce, intensive irrigation can spread malaria and water-borne disease and strain limited water supplies, and soil erosion and intensive fertilizer/pesticide use can pose health risks and environmental damage. Despite the current policy drive to promote urban agriculture, the paper states that the evidence base for its benefits and harms is not well understood. As a protocol, it reports planned search, screening, bias-appraisal and synthesis methods rather than results.

QI Airon · · China

A study of Xi'an, China, built indicators for urbanization and urban agriculture development and applied principal component analysis and correlation analysis to examine their interaction mechanism and quantitative coupling relationship. Urbanization was found to promote urban agriculture's commercialization and scale through market effects and information diffusion, but rapid urbanization's rising population and industrial land use also strained land and water resources and degraded soil and the urban ecological environment, constraining urban agricultural development.

Sylvestre Dasylva · Journal of environmental science & engineering · Senegal (Dakar)

This paper discusses rainwater management in the "niayes" zone of Dakar, Senegal. This area is characterized by agricultural depressions with typically high groundwater levels, but a recent drop has turned some into runoff-gathering sites, used for urban agriculture among other services. However, two acute problems are observed: hydrological drying due to insufficient rainwater refill and urbanization of these bottom-lands. Furthermore, decreasing pluviometry exacerbates nuisances like floods and malaria.

FU Li-hua · 自然资源学报 · China (Shanghai)

A study of Shanghai, China, building an evaluation index system reflecting the characteristics of sustainable urban agricultural development, using a combination of the analytic hierarchy process (AHP) and the information entropy method to determine index weights, and applying it to time-series data from 1993 onward to produce a quantitative, comprehensive appraisal. The results comprise three findings. First, the population subsystem progressively became a main obstructive factor for sustainable urban agricultural development, the economic subsystem gradually became a main contributing factor, and the social subsystem grew more important in raising development capability, while cultivated land resources became increasingly scarce and continued to decrease, constraining improvement, and the heavy burden of agricultural production's self-pollution had a negative effect on the overall upgrade of development capability. Second, the resource (R-D) composite index was not high and declined significantly, averaging 1.9090 over 1993-2006 and falling 6.00% per year from 2.5336 in 1993 to 0.5541 in 2006, indicating growing resource pressure; the environmental (E-D) composite index was smaller and changed little, remaining around 1.0000 in most years, with environmental pressure staying high but stable. Third, after earlier wave-like fluctuations, the overall composite evaluation index entered a sustained, steady climb, with a significant increasing trend in development capability.

Nicola Silvestri, E. Bonari · CINECA IRIS Institutial research information system (University of Pisa) · Italy

Focusing on the area around Lake Massaciuccoli in Tuscany, Italy, this paper discusses the relationship between the management of peri-urban agricultural land — the transition zone between city and countryside — and the lake's eutrophication problem. It argues that proper management of the extensive agricultural areas within this heavily anthropized territory could contribute significantly to resolving the lake's eutrophication through management and structural interventions, while noting that partially reorganizing existing agricultural models carries both cost and difficulty.

Mattia Celio, Christopher A. Scott, Mark Giordano · Geographical Journal · India (Hyderabad)

A study in Hyderabad, India, examined urban water capture and its impacts on pre-existing claims, particularly agriculture. Urban water appropriation often leads to conflict with existing water uses. The findings indicate that the magnitude and direction of impacts from urban water transfer on agriculture vary spatially and temporally, depending on location-specific rainfall patterns, existing water infrastructure and institutions, and farmers' adaptive capacities, including recourse to groundwater.

P. S. Datta, Shipra Tyagi · · India

Peri-urban agriculture in the Delhi-NCR area is highly dependent on groundwater availability amid rapid urbanization. This study integrates dynamic δ18O isotopic composition data on groundwater with static data such as elevation of recharge sites to delineate potential recharge zones and hydrodynamic aquifer zones. Significant δ18O-elevation relationships were found (r² = 0.808 to 0.982), with recharge-site elevation resolutions of about 20m in the northwest and 75m in the southwest, identifying potential recharge zones at elevations of 210-230m in the northwest and above 260m in the south. However, variation in groundwater isotopic composition over time indicates that the corresponding aquifers are relatively small and of low productivity, and points to the likely presence of many low-permeability zones in the northwestern recharge areas — a constraint on the groundwater resources that sustain peri-urban agriculture there.

Kenny Lynch · · Indonesia (Jakarta)

This piece reviews the literature on urban agriculture (UA), noting that Bryceson (1993) provides documentary evidence from as early as 1939 of UA's importance during and after the Second World War, and that the UN University's Food Energy Nexus research programme in the mid-1980s prompted researchers to examine agricultural cultivation within city boundaries more seriously. Since then, a significant body of literature has developed around a central debate over whether urban agriculture is beneficial, summarized by Lynch (2002). This summary is described as having two problems: it assumes urban agriculture is a homogenous activity with universally similar impacts, and it is largely viewed from the perspective of a city's population, so urban agriculture tends to be seen as beneficial for food, employment and the environment with little consideration of its impacts on the rural-urban food supply. This led Lynch, Binns and Olofin (2001) to argue that urban agriculture should instead be considered part of the broader urban food supply system.

Ausaf-ur Rahman, Mohammad Ait Kadi, Johan Rockström · Water Science & Technology · Global

A synthesis paper from a 2002 workshop reports that competing demand for water between agriculture and urban users is generating severe stress on water resources, with virtual water trade (importing food instead of pursuing self-sufficiency, to conserve real water resources) and water reuse (irrigation with treated urban wastewater) emerging as the two dominant proposed responses. It states that virtual water trade carries serious political and economic risks, with one proposed remedy being an international virtual water trading council.