Urban foodprints (UF) – Establishing baseline scenarios for the sustainability assessment of high-yield urban agriculture

Allowing for significant water savings and year-round yields, Controlled-Environment Agriculture (CEA) is oftentimes portrayed as a sustainable alternative to conventional farming, and its practice in urban areas as a food, income and employment generator is expanding worldwide. Particularly in today's fast growing cities, where economic strength is buying food security through imports, a largescale implementation of such practices should be further investigated as potential contributors - not only to food security but also to self-sufficiency - for the production of horticultural crops. However, further than quantifying the potential for food self-sufficiency of cities through urban cultivation, there is a crucial need for assessing the extent to which such scenarios are effectively more sustainable than existing supply chains. For that purpose, this paper presents the Urban Foodprints (UF) methodology, a fundamental preliminary step in the sustainability assessment of high-yield urban agriculture, consisting of collecting and integrating data on the existing supply chain, to be used as a baseline scenario in the environmental performance analysis. Through the case of Riyadh, Saudi Arabia, where harsh climatic conditions, a heavy reliance on food imports and a growing population constitute major threats to food security, the UF method is described and applied to the top four consumed horticultural crops - watermelon, tomato, onion and carrot. The environmental sustainability of high-yield urban agriculture in Riyadh is subsequently assessed for tomato, as a comparison of the resulting city's current foodprint for the crop vs. a scenario of local production in CEA urban farms. Results show that urban production in high-yield greenhouses has the potential to reduce Global Warming Potential (GWP) by 9%. However, while water savings contribute greatly to reducing irrigation-related emissions and food miles are considerably reduced, the energy needs of the greenhouses are significantly higher than the baseline. This outcome may be improved by enhancing the envelope of the farms to reduce overheating. Keywords: baseline scenario; Controlled-Environment Agriculture (CEA); sustainability assessment; Urban Foodprint; urban food syste

Mycotoxigenic fungi contaminating wheat; toxicity of different Alternaria compacta strains

We studied mycotoxigenic fungi contaminating stored wheat grain, measured the toxins they secreted, and assessed their harmfulness. We focused on one common genus Alternaria, and chose 19 isolates representing A. compacta to study how different strains differed in their mycotoxin secretion and toxicity. Toxicity was assessed in a bioassay with a model bacteria Bacillus subtilis. All 19 A. compacta strains secreted toxins. Both the mycotoxin pattern and the fungal toxicity differed between the A. compacta stains. It seemed that some other toxins than alternariols or altenue acted as the main virulence factors of A. compacta against B. subtilis. We suggest that the most commonly studied mycotoxins do not necessarily indicate the toxicity of the fungi. The high variation in the amounts and toxins that different Alternaria species and strains secrete pose a challenge to the food supply chain. Keywords: Alternaria, Mycotoxins, Wheat grains, B. subtili