Potential for high contribution of urban gardens to nutrient export in urban watersheds

Gaston E. Small, Niklas Martensson, Benjamin D. Janke, Geneviève Suzanne Metson

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Urban gardens and farms typically use compost as a source of nutrients, often at levels that exceed crop nutrient demands. Although land dedicated to agriculture is a small fraction of urban land use, high input rates coupled with low nutrient use efficiencies suggest that export of nitrogen (N) and phosphorus (P) from this land could be potentially important contributors to urban nutrient budgets. We used the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) Nutrient Delivery Ratio model to examine the potential impact of garden density, compost input rates, and nutrient retention efficiency on N and P export from stormwater runoff for a 737-ha urban residential area in Saint Paul, Minnesota. Although gardens and farms accounted for 0.1-0.5% of land area in our scenarios, compost inputs accounted for as much as 33% of N inputs and 85% of P inputs to the urban landscape. The contribution of gardens to urban nutrient export through stormwater runoff is highly dependent on modeled maximum retention efficiency values. If retention efficiency is high, gardens with low compost inputs are similar to other vegetated land uses in contributions to nutrient export, but gardens become significant contributors to watershed P export if compost inputs are high, or if retention efficiency drops to 75% or lower. These results underscore mass-balance constraints inherent in urban nutrient recycling and highlight the importance of understanding the long-term fate of excess nutrients applied to urban landscapes.

Original languageEnglish (US)
Article number104602
JournalLandscape and Urban Planning
StatePublished - Jan 2023

Bibliographical note

Funding Information:
This work was supported by a National Science Foundation CAREER award (award number 1651361) to GES, the Minneapolis-St. Paul Metropolitan Area (MSP) Long Term Ecological Research Program (NSF award number 2045382), and the Swedish Council for Sustainable Development (Formas-2019-01890) to GSM and GES.

Publisher Copyright:
© 2022 The Author(s)


  • Nitrogen
  • Phosphorus
  • Runoff
  • Stormwater
  • Urban agriculture


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