Harvesting of Agricultural Nutrient Runoff with Algae, to Produce New Soil Amendments for Urban and Peri-urban Olive Tree Agroforestry Systems in Southern Europe

Biomimicking has long been an interest of many scientific and engineering fields. When two ecosystems overlap, we have the famous edge effect. In this article, we want to explore getting the same abundance of life using a biomimicry approach to agroforestry by bringing aquatic life full of nutrients to the soil. These nutrients would otherwise harm the marine ecosystem and in this way, as they get removed before reaching the sea, they help grow life on land, while preserving marine life. Nature-based solutions to water management are usually grouped into five established categories, adding to this well-established lists could be harvesting agricultural nutrient runoff with microalgae, and using them as soil amendment in peri-urban and urban settings, especially focusing on olive trees in and around Mediterranean and Greek cities. The ancient olive tree is a cornerstone for further research, not only because of its general tolerance to drought, very easy management, somewhat salt tolerance, but above all its overwhelming presence in the whole Mediterranean basin. Here we will try to identify at least three most accessible sites for implementing a nutrient runoff harvesting system using algae in Greece. These sites will be characterised by infrastructure development, levels of nutrients present in the waters, vicinity to an urban area as well as vicinity to a highly cultivated area, local willingness to experiment and collaborate in for developing an urban (or peri-urban) agroforestry system with the traditional olive tree as the central income-generating species. The main research methodology consists of an extensive multidisciplinary literature review, aimed at gaining valuable insights on three issues. Firstly, the source location of the nutrient runoff that produces the algal blooms shall be identified. Secondly, treatment methodologies and practices identified to generate biostimulants and soil amendments from algae are highlighted. Thirdly, identifying the best combination of plants and crops to support nutrient absorption and complement the olive trees’ growth.