Many studies examine the correlation between the use of resources such as water, energy and land, and the production of food. These nexus studies focus predominantly on large scale systems, often considering the social dimensions only in terms of access to resources and participation in the decision-making process, rather than individual attitudes and behaviours with respect to resource use. Such a concept of the nexus is relevant to urban agriculture (UA), but it requires customisation to the particular characteristics of growing food in cities, which is practiced mainly at a small scale and produces not only food but also considerable social, economic, and environmental co-benefits. To this end, this paper proposes a new conceptual basis for a UA Nexus, together with an assessment methodology that explicitly includes social dimensions in addition to food, energy and water. The conceptual basis introduces People, together with Food, Energy and Water, as a fundamental factor of the UA Nexus. On this basis, a methodology is developed measuring not only resource efficiency and food production but also motivations and health benefits. It comprises a combination of methods such as diaries of everyday UA practices, a database of UA activities, life cycle assessment (LCA), and material flow analysis to connect investigations developed at a garden scale to the city scale. A case study shows an application of the methodology.

Socioeconomic and climatic changes and limited water resources pose various challenges to water, energy, and food sectors across the globe. The inevitable interactions between water, energy, and food systems bring about trade-offs but also synergies under different decisions and policies. To gain insights into these issues, we developed a water-energy-food (WEF) nexus model that incorporates both production (supply) and demands sides of WEF systems into a single system-of-systems model using the system dynamics (SD) approach. The model is applied to Saskatchewan, Canada, and so is named WEF-Sask. The model results reveal the various levels of sensitivities of water, energy, and food (and feed) sectors to the socioeconomic and climatic drivers. The analysis of trade-offs and synergies shows that the proposed large irrigation expansion (400%) boosts food production by 1.6% while reducing hydropower production by 2.7% in Saskatchewan. Wind energy expansion strategy (from 5% to 30% of total capacity) makes synergies that not only contribute to electricity supply but also reduce greenhouse gas emissions, industrial water demand, and groundwater use by 2.0, 5.7, and 3.8%, respectively. Biofuel use (blending mandate: 10% ethanol and 5% biodiesel) in transportation cuts GHG emissions by 1.2% but reduces the potential food export (food surplus) by 5.0%. The WEF-Sask model allows for scenario analysis toward integrated resources management, and its generic model structure can be expanded to other regions.

The study explores complex non-linear decisions in land use allocation, focusing on the competition between cash and food crops. We develop an agent-based model to investigate whether the decision to opt for eucalyptus plantation is a rational choice in the perspective of different farmer types. We analyse the negative externalities (i.e. allelopathic effects) caused by the presence of eucalyptus on the productivity of neighbouring plots and the possible spill-over effects. The findings demonstrate that cultivation of eucalyptus as a cash crop may improve the rural populations' well-being only if there are no physical and economical constraints on access to food and services. The model shows that the allelopathic characteristics of eucalyptus strongly affect the soil fertility, inhibiting the possibility to switch to food crops in the future. In addition, the results of policy scenario simulations indicate that government environmental policies can play a key-role in improving awareness of the ecological effects of eucalyptus plantation on soil fertility in fragile socio-economic contexts characterized by high ecological vulnerability.

Water is a basic resource for food and fuelwood production. In general, people in rural areas of India consume carbohydrate rich staples with small amounts of animal foods. They mostly depend upon fuelwood for cooking. This study assesses the WFs for food and fuel consumption in rural India. The research question is: What is the green, blue and grey water footprint (WF) of food and cooking fuel consumption per province in rural India (m³/cap/year). It used the WF method for the quantification. Data on food and fuelwood consumption were derived from the National Sample Survey (2011–12). Foods were categorized into 6 groups: 1. Rice; 2. Wheat; 3. Oils and fats; 4. Milk; 5. Other animal foods; and 6. Others. Cooking fuel includes: 1. Fuelwood; 2. Kerosene and 3. LPG. Data related to WFs of food were derived from literature reviews and in case of fuelwood, the WFs were calculated for all the provinces of India. Finally, the total WF of per capita consumption is calculated by adding the WF of food and fuelwood. The result shows that there is a large variation in the green, blue and grey WFs for food consumption across the provinces of India. The average WF for food consumption is about 800 m³/cap/year and for fuelwood is 1630 m³/cap/year. Rice and wheat dominate the green, blue and grey WFs for food, with variations among the provinces. The green WF of rice is larger than the green WF of wheat, while wheat has a larger blue WF. For cooking fuel, the average WF of fuelwood is much larger than the WF of fossil based cooking fuels. The total WF for fuelwood is twice the WF for food, showing that in rural areas of developing countries, fuelwood is water intensive with large impact on freshwater resources. Future prospects of increasing consumption of animal products will increase WFs. However, if also cooking fuel is considered, switching to fossil cooking fuel lowers WFs far more and compensates the increase due to larger animal food consumption. The trends for cooking fuel found in India might also be relevant for other developing countries.