Modeling the Potential Productivity of Urban Agriculture and Its Impacts on Soil Quality Through Experimental Research on Scale-Appropriate Systems

Abstract

Urban agriculture could play a central role in local and regional food sovereignty in developed countries, but in many cities, a lack of space and competition with other land uses limit production. Options for meaningfully advancing food sovereignty goals include sustainable intensification of existing urban farms and gardens; (2) expansion of production into interstitial and other underutilized spaces undevelopable for other purposes; and (3) expansion of production in protected environments. Observational studies suggest that-like smallholder agriculture in the Global South-urban home, community, and market gardens in the developed world can be highly productive-but often are not. Research on scale-appropriate systems and outreach to urban agriculturalists are needed to help them grow more food, more sustainably. This replicated, long-term trial is addressing this need-and a dearth of experimental, normative research on urban agriculture-by evaluating the yield performance and impact on soil quality of four different systems of small-scale food production in Rhode Island, the second most densely populated state in the United States and a potential model for the development of sustainable urban food systems. Systems are modeled on vernacular systems in Providence, RI and Chicago, IL and on the scholarly and gray literature on sustainable intensification. They differ in soil management practices and nutrient sources. Results from the first 3 years of data collection indicate all four systems can be highly productive, with varying tradeoffs in terms of their sustainability and impacts on soil quality. While total marketable food yields were relatively modest compared to those reported in the gray literature for biointensive agriculture−2.22-2.96 kg m −2 averaged over three summer growing seasons compared to 4.64 kg m −2 for the "low end" of biointensive production-yields for individual crops generally exceeded-and often far exceeded-regional averages and, for most crops and systems, national averages, without a loss in soil quality. In addition to demonstrating the high productivity of small-scale systems compared to commercial farms, the study establishes a framework for conducting normative, experimental research that can help to guide practice. It also offers more reliable yield estimates for modeling the production potential of cities than do observational studies and agronomic experiments on monocultures.

Chemical and biological indicators of soil health in Chicago urban gardens and farms

“…Because of differences in scale, inputs, and context, agronomic research on commercial farming practices may not provide adequate guidance for the development of alternatives to this perceived standard of management. Instead, experimental research is needed to develop scale‐appropriate best management practices that help gardeners and farmers maximize the ecosystem services of urban food production systems while minimizing their disservices (Taylor, 2020). For example, sites identified with excessive inorganic P values in a soil test would benefit from the use of plant‐based fertility instead of compost‐based materials.…”

Leaf mold compost reduces waste, improves soil and microbial properties, and increases tomato productivity

“…These results are comparable with other studies observing dramatic increases in crop productivity because of compost amendments derived from urban waste streams. For example, in one study, researchers observed an 86% increase in marketable vegetable yield after amending soil with a local yard waste compost (Taylor, 2020) and in another, compost‐amended plots on urban farms produced eight to ten times more tomato fruit (Beniston et al., 2016). While these results are exciting and validate reports by our local growers of the value of leaf mold compost for urban farms, not all compost applications are likely to result in such dramatic benefits.…”

A Comprehensive Review on Evolution, Challenges of Models, Opportunities in Urban Farming Practices in the World

“…There will be around 130 million individuals who are experiencing severe food insecurity by the end of the year 2020. The seriousness of the situation is clearly shown by the present global food crisis and the consequences that it has brought about [30].…”