Abstract
Urban agriculture provides opportunities for reducing impacts of agricultural practices because of the roximity of production to the final consumer. Within urban agriculture, soilless system deliver a closely controlled environment with sparse amounts of pathogens, independent of soil, which is a scarce resource in cities. If these systems are to be sustainable in the long run, the nutrient flows on which they depend, need to be made cyclical and closed. In particular close attention should be paid to the phosphorus cycle since peak phosphorus may be reached as soon as 2033. The main objective of this study is to explore the ways in which these nutrient flows can be transformed into closed cycles, by preparing compost extracts or Teas, from materials typically available in cities. The first phase of the project will be the preparation and analysis of compost and compost teas to compare them with the nutrient solutions used in soilless systems. Then a growth experiment will be conducted to compare the performance of compost extracts with commercial nutrient solutions. And in situ experiments will be carried out to determine if the production of compost extracts is simple enough to be carried out by city and peri-urban dwellers of mountain areas (both in Europe and in the Andean ranges) without scientific training. The results expected include the degree to which the cycles of nutrients can be closed, the nutrient contents of diverse compost extract recipes, the performance of crops grown under compost extract regime and the considerations to be taken into account when promoting these systems as solutions to climate change and improved sustainability.