Rooftop production of leafy vegetables can be profitable and less contaminated than farm-grown vegetables

Abstract

Urban agriculture may solve issues of feeding urban populations. In China, for example, densely packed mega cities will continue to expand in number and size, necessitating increasing food miles. Interestingly, it has been estimated that the total rooftop space in China is about 1 million hectares, some of which can be converted for rooftop farming. Yet, despite some favorable reports on urban farming, the Chinese commercial sector has shown little interest. This may be explained by the dearth of data comparing urban and conventional farming. Therefore, we present here a feasibility study of hydroponically grown vegetables in a rooftop screen house in Guangzhou, China. From December, 2012 to May, 2014, we tested the production of seven leafy vegetables that are easily perishable and are not well suited to long-distance transport. We calculated the production cost and measured biochemical parameters. Results show that levels of vitamin C, potassium, calcium, magnesium, iron, zinc, and crude fiber were comparable to market counterparts. None of the roof hydroponic vegetables exceeded the maximum residue limit for lead, arsenic, cadmium, chromium, mercury, or nitrate. In contrast, 5 of 98 market vegetables were contaminated by exceeding the maximum residue limit for lead. Similarly 3 were contaminated for arsenic, 23 for nitrate, and 2 for organophosphate or carbamate insecticide. Compared to high-end vegetables sold on the market, rooftop-grown vegetables were competitive in cost and quality. Given that many countries have limited arable land to feed a large population, the widespread adoption of rooftop hydroponics could help expand the total area available for food production as well as meet the rising demand for safe high-quality vegetables.

A Moisture‐Hungry Copper Complex Harvesting Air Moisture for Potable Water and Autonomous Urban Agriculture

“…[ 40 ] It has the advantage of utilizing existing land in cities to sustainably produce food locally. [ 41 ] Thus, rooftop farming potentially reduces the carbon footprints from air/land transportation of food supply from distant rural farms and consequently leading to a positive impact on the environment. [ 42 ] As SmartFarm device is a fully automated system that uses only renewable energy and harvests atmospheric water for irrigation, it eliminates the need for human resources to operate and bring down the freshwater usage for agriculture.…”

High-Fat Diet Affects Heavy Metal Accumulation and Toxicity to Mice Liver and Kidney Probably via Gut Microbiota

“…Heavy metals enter and accumulate gradually in the human body through diet uptake. Numerous studies have shown that heavy metal pollution is widely spread in animal and plant products, aquatic products, and various processed foods all over the world (Dadar et al, 2016;Liu et al, 2016;Wijayawardena et al, 2016). Heavy metals that enter the human body through chronic exposure are very difficult to metabolize or decompose, so they accumulate in all tissues and organs over the years and exert chronic damage to the body when they reach a certain threshold (Raehsler et al, 2018).…”

Potential of Technosols Created with Urban By-Products for Rooftop Edible Production

“…[30], type of pollutant, type of plant and soil organisms [31]. An effect of urban pollution is described for different forms of urban agriculture using uncontaminated soils at natural levels trace metals concentrations [32], hydroponic system on rooftop [33] or urban contaminated soils [34,35]. However, to our knowledge the quality of vegetables grown on Technosols made with by-products derived from urban wastes was not informed.…”