Significance and Vision of Nutrient Recovery for Sustainable City Food Systems in Germany by 2050

Abstract

Within this paper, the authors explain their transdisciplinary vision of nutrient recovery for sustainable urban plant cultivation in Germany from different but complementary perspectives (SUSKULT vision). Nowadays, the demand for fresh, healthy, locally and sustainably produced food in German urban areas is constantly increasing. At the same time, current agricultural systems contribute significantly to exceeding the planetary boundaries. The disruption of the phosphorus and nitrogen cycles in particular stands out from the manifold effects of modern food production on the Earth system. One central issue that will have to be faced in the future is how increased yields in agriculture will be achieved with high-energy requirements in fertilizer production and pollution of water and soil by phosphorus and reactive nitrogen. City region food systems (CRFS) can be a solution to overcome these issues. Nevertheless, to ensure sustainable CRFS, innovative technologies and methods need to be developed, including nutrient and energy recovery and adapted horticultural cultivation methods that fit complex urban dynamics. Such new strategies need to be integrated in long-term social and political transformation processes to enhance acceptance of food produced by recyclates. The joint contribution of experts from the wastewater, horticultural, and political sciences, together with industrial and societal sector actors, is critical to reach these objectives. The overarching goal of SUSKULT’s vision is the establishment of the field of urban circular agricultural production as an innovative sector of the bio-based economy in Germany.

The spatiotemporal characteristics and obstacle factors of the coupled and coordinated development of agricultural and rural digitalization and food system sustainability in China

“…The results show that the development (Tang and Chen, 2022;Xu et al, 2022). For the measurement of FSS, existing studies mainly focus on economically developed countries, including the United States (Heller and Keoleian, 2003), the United Kingdom (Yakovleva, 2007), Japan (Tsuchiya et al, 2021), and Germany (Keuter et al, 2021), etc., while studies for developing countries are still scarce. In addition, existing measurement studies on the ARD mainly focus on a local area (Zhao and Li, 2022;Zhu et al, 2023) and regions (states, provinces, or cities, etc.)…”

Lemnaceae as Novel Crop Candidates for CO2 Sequestration and Additional Applications

“…Control of environmental factors allows optimization of biomass quality, i.e., micronutrients (vitamins, antioxidants) and proteins for use as food [131] or either starch or lipid content for use as biofuel feedstock. Recirculation of nutrients and water prevents nutrients release into the environment and resulting land and water pollution [132], as well as minimizes water loss [128] by reducing evaporation (proximity between different vertical levels could act as "semi-closed lids"). Duckweed, furthermore, thrives on a film of water [133].…”

Influence of Light Intensity and Spectrum on Duckweed Growth and Proteins in a Small-Scale, Re-Circulating Indoor Vertical Farm

“…One possible solution in the future might be the cultivation of duckweed in re-circulating (also described as closed) indoor vertical farms (IVF) with artificial lighting. By stacking several layers of cultivation areas above each other, the land utilization efficiency is increased [13,14]. When operating an IVF in a controlled environment, it is possible to regulate plant-relevant abiotic factors, e.g., nutrient composition and concentration, light intensity and spectrum, photoperiod, the temperature of water and air, water flow rate or humidity according to the grower's demand.…”

“…This can positively affect the quantity and quality of the crops. Additionally, the use of IVFs will allow year-round crop production, even in areas with short growing seasons or unfavorable climatic conditions [13][14][15][16]. One shortcoming of this cultivation technology is the relatively high energy input, e.g., the production of one kg of curled lettuce required 7-9 kWh of electric energy [14].…”