Last century witnessed an unprecedented growth of cities which has led to the consolidation of an eminently urbanised world population. Meanwhile, agriculture has adopted industrial methods of production in the shape of large-scale, chemical-laden crops in the countryside, which, together with the liberalisation of global trade, have undermined the livelihood of small-scale peasants throughout the world, forcing many of them out of business. The food industry has responded to the high rates of hunger and malnutrition with an extraordinary increase in production that has not solved food security problems, as these have turned out to be more a question of unequal access to food rather than insufficient supply. Furthermore, the activity of large agri-food corporations has resulted in the degradation of natural ecosystems and an increasing pressure over already overburdened critical resources for food production. Consequently, facing the imminent threat of climate change, more and more voices are questioning the sustainability of the current food system and rising against the burgeoning hunger and escalating inequalities resulting from it. Hence, several alternatives to the neoliberal food system are emerging these days with the aim of reducing social inequalities and curbing environmental degradation, being urban agriculture one of them. Precisely, this thesis explores, from a social-ecological justice perspective, whether urban agriculture can address issues of environmental stewardship and disparities in food distribution. Although the many virtues of urban farming might not be enough to subvert the structures of power that are deeply rooted in the foundations of the present food regime, it could still play a significant role in alleviating the gaps in food needs. However, food security comes only after the core reasons of poverty have been addressed and social justice is achieved in the larger society. The pathway towards a greater social and ecological justice seems to require not only to re-examine how to feed the urban population, but also a significant transformation that goes beyond aspects from the whole food supply chain and embraces societal systemic change.

L’intensità del trasporto alimentare è un trend destinato ad aumentare nella sua complessità. La ricerca attesta come sia rilevante analizzare “come il cibo viaggia”, forse più di “quanto il cibo viaggia”, nel mercato globalizzato dei prodotti agroalimentari, nelle realtà urbane che modificano le abitudini di consumo e nel “global food system” composto da cinque tipologie di sistemi agroalimentari. Gli impatti in sostenibilità sono strettamente dipendenti dall’efficienza del trasporto e della logistica, di merci agroalimentari e di persone che si spostano per l’approvvigionamento, dal campo al consumatore e viceversa. Eppure il concetto di food miles si è ampiamente diffuso tra gruppi di consumatori, attestando mutamenti culturali significativi. Si pensi all’idea tutta italiana di “km-zero”. “Può il trasporto del cibo essere economicamente, socialmente e culturalmente sostenibile, per conservare l'ecosistema?” Questa domanda, approfondita pedagogicamente, può essere riformulata: “How can consumers, economical stakeholders and policy makers become environmentally friendly about transportation of food?” Il quesito conduce all’interrogativo di quale formazione e ricerca interdisciplinare progettare per orientare gli sforzi verso questo fine. Una nuova formulazione concettuale potrebbe promuovere azioni sostenibili per la mobilità e i trasporti sulle lunghe, medie e corte distanze, per la filiera lunga e corta: il “Kmetro verde”. / The transportation of agro-alimentary products is constantly evolving. The research has been focusing on long distances, tied with the global market. But results in a lack of investigations in medium and short distances which also possess some efficiency gain. The investigation of these shorter mode of transport is paramount as they have significant impact on the triptych of sustainability. In this context, the concepts of "food miles" and of "km-zero" have spread widely among the consumers, attesting the community awareness regarding sustainability issues. However, as environmental concerns arise, such concept has showed it's limit. Therefore the question, "Can transportation of food become economically, socially and culturally sustainable, to preserve the ecosystem?", that lead to this concept, needs to be reassessed. Starting from a pedagogical standpoint, this question can be rephrased as “How can consumers, economical stakeholders and policy makers become environmentally friendly about transportation of food, to preserve the ecosystem?”. For a successful undertaking of such problematic, it is paramount to evaluate the need of novel training practises as well as the design of interdisciplinary research. A new formulation of such concept, embodied in "kmeter green", would aim to promote sustainable mobility on all the distances and chains' lengths.

The story of phosphorus began with the search for the philosopher’s stone, and centuries later the critical role of phosphorus in soil fertility and crop growth was highlighted. Eventually, phosphorus was implicated in the global environmental challenge of eutrophication. Now, we are on the brink of yet another emerging chapter in the story: global phosphorus scarcity linked to food security. Through a transdisciplinary and systemic inquiry, this thesis has analyzed, reconceptualized and synthesized the physical and institutional dimensions of global phosphorus scarcity in the context of food security, leading to a new framing, ‘phosphorus security’ to guide future work towards a more sustainable and food secure pathway. In a world which will be home to nine billion people by the middle of this century, producing enough food and other vital resources is likely to be a substantial challenge for humanity. Phosphorus, together with nitrogen and potassium, is an essential plant nutrient. It is applied to agricultural soils in fertilizers to maintain high crop yields. Phosphorus has no substitute in food production. Therefore, securing the long-term availability and accessibility of phosphorus is crucial to global food security. However the major source of phosphorus today, phosphate rock, is a non-renewable resource and high quality reserves are becoming increasingly scarce. This thesis estimates peak phosphorus to occur before 2035, after which demand will exceed supply. Phosphorus scarcity is defined by more than just physical scarcity of phosphate rock and this thesis develops five important dimensions. For example, there is a scarcity of management of phosphorus throughout the entire food production and consumption system: the global phosphorus flows analysis found that only 20% of phosphorus in phosphate rock mined for food production actually reaches the food consumed by the global population due to substantial inefficiencies and losses from mine to field to fork. There is also an economic scarcity, where for example, while all the world’s farmers need access to sufficient fertilizers, only those with sufficient purchasing power can access fertilizer markets. Institutional scarcity, such as the lack of governance structures at the international level that explicitly aim to ensure long-term availability of and access to global phosphorus resources for food production that has led to ineffective and fragmented governance of phosphorus, including a lack of: overall coordination, monitoring and feedback, clear roles and responsibilities, long-term planning and equitable distribution. Finally, geopolitical scarcity arising from 90% of the world’s remaining high-grade phosphate rock reserves being controlled by just five countries (a majority of which are subject to geopolitical tensions) can limit the availability of phosphorus on the market and raises serious ethical questions. The long-term future scenarios presented in this thesis indicate that meeting future global food demand will likely require a substantial reduction in the global demand for phosphorus through not only improved efficient use of phosphorus in agriculture, but also through changing diets and increasing efficiency in the food chain. The unavoidable demand for phosphorus could then be met through a high recovery and reuse rate of all sources of phosphorus (crop residues, food waste, manure, excreta) and other sources including some phosphate rock. A ‘hard-landing’ situation could involve further fertilizer price spikes, increased waste and pollution (including eutrophication), increased energy consumption associated with the production and trade of phosphorus fertilizers, reduced farmer access to phosphorus, reduced global crop yields and increased food insecurity. A preferred ‘soft landing’ situation will however require substantial changes to physical and institutional infrastructure, including improved governance structures at the global, national and other levels, such as new policies, partnerships and roles to bring together the food, fertilizer, agriculture, sanitation and waste sectors for a coordinated response. Finally, this thesis proposes a new global goal – phosphorus security – to be integrated in the dominant research discourses and policy debates on global food security and global environmental change. Among other criteria, phosphorus security requires that phosphorus use is decoupled from environmental degradation and that farmers’ access to phosphorus is secured.

Current global agricultural practices are recognized as unsustainable. The increase in overall human population as well as the global trend of rural to urban migration, partially as a result of historically and continual unsustainable agricultural practices, exacerbates the vicious cycle of poverty and hunger in developing countries. Furthermore, cities and regions in developed countries practice unsustainable food production, distribution and consumption patterns, and as a result, exceed their global ecological footprint (Rees 2009). Consequently, the world is facing a global food (FAO 2009) and water crisis (UN Sick Water 2010). Cities and Regions must learn to feed themselves to address local food insecurity as well as protect from the climate effects of increased urbanization, including the Urban Heat Island effect (UHIe) by optimizing and fully integrating the local ecosystem services of food, water and forest within a tightly woven compact urban form through the implementation of strategic urban and regional food system planning. Cities can mitigate climate change and reduce the UHIe, by implementing sustainable intensive urban agriculture approaches through policy and zoning interventions that include concepts such as intensively productive urban agriculture that includes green roofs, vertical farming and greenways as continuously productive and edible urban landscapes, referred to in this paper as continuously productive urban agriculture and forestation (CPUAF) in the private and public realm. A highly participative, adaptive systems approach is explored as the key to sustainability within an economic world order that included corporate social responsibility and social enterprise as the foundation for the integration of multiple synergies. An increasing body of evidence often links urban forestation with urban greenery initiatives, as a carbon sink to reduce UHI effects, to reduce GHG emissions and as a tool for urban beautification and place making (ISDR: 2009,109). Urban agriculture, through the production of local food is increasingly recognized as a means to reduce fossil fuel emissions by reducing transportation and production outputs, to provide a secure local food source, enhance biodiversity and educate the public regarding food source while fostering a sense of community, environmental awareness and stewardship. This thesis explores the links between intensive urban agriculture and forestation, and the relationship between climate change, and the UHI’s as an adaptation and mitigation process in global cities, implemented as a interconnected, integrated, holistic urban management approach that has a further benefit of providing food security and a sustainable and local urban food source. / Dissertation (MTRP)--University of Pretoria, 2012. / Town and Regional Planning / unrestricted