期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2019
卷号：116
期号：1
页码：129-134
DOI：10.1073/pnas.1809707115
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A major challenge of the 21st century is to produce more food for a growing population without increasing humanity’s agricultural footprint. Urban food production may help to solve this challenge; however, little research has examined the productivity of urban farming systems. We investigated inputs and produce yields over a 1-y period in 13 small-scale organic farms and gardens in Sydney, Australia. We found mean yields to be 5.94 kg⋅m−2, around twice the yield of typical Australian commercial vegetable farms. While these systems used land efficiently, economic and emergy (embodied energy) analyses showed they were relatively inefficient in their use of material and labor resources. Benefit-to-cost ratios demonstrated that, on average, the gardens ran at a financial loss and emergy transformity was one to three orders of magnitude greater than many conventional rural farms. Only 14.66% of all inputs were considered “renewable,” resulting in a moderate mean environmental loading ratio (ELR) of 5.82, a value within the range of many conventional farming systems. However, when all nonrenewable inputs capable of being substituted with local renewable inputs were replaced in a hypothetical scenario, the ELR improved markedly to 1.32. These results show that urban agriculture can be highly productive; however, this productivity comes with many trade-offs, and care must be taken to ensure its sustainability.
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