Mikael Brocki, Landscape Engineer programme (BSc)
Urban Rooftop Agriculture is a growing field within the urban matrix which has arisen as a response to rapid population growth and urbanization. Although, suggested to offer several ecosystem services, such as significant vegetable production, there are still uncertainties connected to this novel ecosystem. Appropriate choice of substrate is pointed out as a central factor for the success of vegetables grown on rooftops but there is up to this point no scientific consensus on the issue and contextual best management practice is therefore needed. This study uses a literature synthesis and interviews with scholars and rooftop farmers to investigate substrates for effective vegetable production. By researching its components, depth and organic matter, the aim is to provide rooftop farmers with guidelines on appropriate choice for substrate. It is concluded that no specific component can be recommended. Instead, rooftop farmers should strive to implement components adapted to local needs and conditions, being light-weight, and having a rich existence of internal pores; depths ≤15 cm suffice for effective vegetable production but these shallow depths will require more intense water and nutrient management; additions of organic matter in the form of compost are necessary but proportions needed exceed established guidelines. Ultimately porosity will determine the efficacy of the substrate. Therefore, landscape engineers should be involved in the decision making.