Comparison of organic substrates in urban rooftop agriculture, towards improving crop production resilience to temporary drought in Mediterranean cities

Abstract

BACKGROUND: Urban agriculture contributes to meet food production demand in cities. In a context of low water availability, it is important to consider alternatives that are able to maintain production. This study aimed to assess the use of substrates made from local materials and high water retention capacity as an alternative for urban agriculture in periods with water stress. Different substrates were used for 3 consecutive crop cycles of lettuce (Lactuca sativa L.) during the spring and summer periods of 2018 to observe these substrates performance during warmer periods of the year in an integrated rooftop greenhouse near Barcelona. The substrates used were coir commercial organic substrate, vegetable Compost from urban organic waste, Perlite (as control) commercial standard substrate, and a Mixture of the urban Compost and Perlite (1:1).Substrate crop performance was assessed under conventionally irrigation (0-5 cbar) and water restricted conditions (irrigation stop until the water tension inside the perlite bags reached -20 cbar). RESULTS: The results demonstrate that the Compost and Mix yields were similar to those obtained from Perlite (11.5% y 3.7% of more production in a restricted water condition average values). Compared to the Perlite, the organic substrates increased the crops resilience to water restriction, through biomass accumulation comparison, it took longer for Coir to lose water (1 and 2 test); however, when dryness began, it occurred very quickly. CONCLUSION: The vegetable Compost and the substrate Mixture presented tolerance to water restriction when water restriction reached -20 cbar.

An Evolutionary Approach on the Framework of Circular Economy Applied to Agriculture

“…In this case, it was carried out according to the activity of the main authors. Therefore, Figure 4 crop production resilience to temporary drought in Mediterranean cities" [60] is one of the investigations carried out by said authors; some of those that make up the purple cluster can also be found in this publication. The light blue and orange clusters are the smallest, with four and three authors, respectively.…”

Environmental and social life cycle assessment of growing media for urban rooftop farming

“…kt, kilotons. 1 (Grillas et al 2001;Maher et al 2008;Papadopoulos et al 2008;Barrett et al 2016); 2 (Soil and Substrate Preparers Association 2020); 3, 5 (U.S. Geological Survey 2020); 4 (Growing Media Europe 2019); "a" only for Europe; "b" Coconut production…”

“…In this context, an array of growing media can be used for vegetable cultivation. These substances have to share features such as lightness, porosity and water retention capacity (Maher et al 2008;Papadopoulos et al 2008). In this case study, three constituents were analysed: perlite, peat and coir.…”

“…This separation between the points of production and consumption causes environmental and social impacts that should be screened and included in any new strategy we propose to enhance the sustainability of cities. Notwithstanding, this global delocalisation has also brought prosperity, in some cases, to these countries that have become factories for developed countries (Panagariya 2019). Some of these positive consequences include job creation, GDP increase and improvement of infrastructure (World Trade Organization 2017.…”