Research & reports

Sofía Aguado, Helena Cotler, Marta Astier, Alejandro Padilla‐Rivera · Circular Economy and Sustainability · Latin America

This literature review examined methodologies applicable to municipal composting systems linked to urban agricultural production, with a specific focus on the Latin American context. It revealed a lack of structured methodologies to assess the circularity of municipal organic waste management systems and their connection with urban agriculture, particularly in heterogeneous contexts like Latin American cities, despite numerous existing evaluation methods. Life Cycle Assessment (LCA) is commonly used but often prioritizes environmental impacts, neglecting social, economic, and circularity dimensions.

Jacob Wallace · Waste Dive · United States

NYC's Department of Sanitation began enforcing mandatory curbside organics separation on April 1, 2025, issuing nearly 2,000 summonses in the first week, but Mayor Adams paused broad enforcement through 2025 on April 18, limiting fines to persistent violators. The city had distributed about 190,000 free bins and sold 63,000 more, and organics diversion had risen 65% from FY2022 to FY2024.

Pierric Calenge, Maie Gérardot · Métropolitiques · United States (Cleveland)

The work by Max Rousseau and Vincent Béal illuminates the ambiguities of a policy that organizes urban decline and racial segregation in Cleveland. This policy promotes urban degrowth and racial segregation, balancing algorithmic management and urban greening. The study focuses on the Rust Belt region, which experiences de-urbanization marked by the subprime crisis, racism, and segregation.

Wendy J. Heiger-Bernays, Alicia Fraser, Valerie Burns, Kerry Diskin, Diedre Pierotti, Kian Merchant-Borna, Michael D. McClean, Daniel J. Brabander, H. Patricia Hynes · Scholarworks (University of Massachusetts Amherst) · United States (Boston)

This study identified the nature and extent of soil contamination by polycyclic aromatic hydrocarbons (PAHs) from railroad ties and arsenic from chromated copper arsenate (CCA) pressure-treated lumber in a representative community garden in Boston. Elevated levels of PAHs and arsenic were present in the gardens studied, with these timbers serving as a continuous source of contaminants. This is the first study to investigate contaminants other than lead and evaluate the effect of adding city compost on select soil contaminants in urban garden soil.

Cascadia Consulting Group · Washington State Department of Ecology · United States

A report to the Washington State legislature summarizing an advisory committee's research on standards for managing compostable products at composting facilities. Compostable products make up only 0.4% by weight of material sent to commercial compost facilities in the state, yet the associated contamination disproportionately raises processing costs, and consumer confusion is identified as a major driver of misdisposal.

Jordi Guimera Garcia, Natalie Bray, Yowhan Son, Aleah L. Butler-Jones, Sara Perl Egendorf, Jenny Kao‐Kniffin · Journal of Urban Ecology · United States (New York City)

In New York City, a study investigated plant growth (tomato, pepper, kale) in soils constructed from four municipal composts mixed with sediments from the NYC Clean Soil Bank, to assess the potential for safe urban agricultural soils. While Clean Soil Bank sediments enhanced plant growth when mixed with BRL compost, they also negatively impacted tomato aboveground biomass production by 29% in LES compost and tomato plant height by 18% in QBG compost, indicating variable effects depending on compost properties.

Jordan Ashby, Clarissa Libertelli · Institute for Local Self-Reliance (ILSR) · United States

Just after NYC announced expansion of mandatory residential organics collection by 2024, the mayor's office eliminated funding for the city's community composting program. The article identifies three failures reflecting national trends: government 'composting' programs that actually rely on anaerobic digestion, centralized processing that concentrates environmental burdens in vulnerable neighborhoods, and mandatory government programs undercutting community composters' viability.

Cole Rosengren · Waste Dive · United States

California's Little Hoover Commission recommended pausing SB 1383, the state's organics recycling law, citing concern the state will miss its 2025 targets, but CalRecycle, industry and environmental advocates strongly opposed the pause, noting roughly $500 million already invested. 445 of 614 jurisdictions now have residential food-waste collection programs, and waste costs rose 20% for residential and 30% for commercial customers.

Chammi P. Attanayake, Ganga M. Hettiarachchi, Mónica Palomo, Gary M. Pierzynski, Blanca Calderón · ACS Agricultural Science & Technology · United States

The effect of limestone and composted manure on lead (Pb) in vegetables and Pb bioaccessibility was assessed in a contaminated urban garden (total Pb ~200 mg kg⁻¹). Amendments did not affect Pb in vegetables or Pb bioaccessibility. Peeling reduced Pb concentration in radish by half, and removing surface dust reduced Pb in leafy vegetables by 40-50%. Daily Pb intake from consuming lettuce and carrot/beetroot from this garden was approximately 1.5 times higher than the interim reference level proposed by the U.S. Food and Drug Administration.

Rafael Carvalho Machado, Sieglinde Kindl Da Cunha · Waste Management & Research The Journal for a Sustainable Circular Economy · Brazil (Curitiba)

This study investigated Curitiba, Brazil's Urban Agriculture Program (UAP) and its decentralized composting strategy, which aimed to close the agricultural loop within city bounds. Despite training 24 urban farmer communities in composting techniques, the program was unable to achieve this goal. The research, based on secondary data review, interviews, and participatory observation, identified cultural barriers and conflicts among actor roles within the UAP that hindered the adoption of composting practices.

Gaston E. Small, Paliza Shrestha, Geneviève S. Metson, Katherine Polsky, Ivan Jimenez, Adam D. Kay · Environmental Research Communications · United States

Survey data from 142 gardeners and urban farmers in the Twin Cities Metropolitan Area, USA, characterized phosphorus (P) and nitrogen (N) inputs and harvest, and measured soil P concentrations at a subset of sites. Median application rates were 300 kg P/ha and 1400 kg N/ha, with low nutrient use efficiencies (2.5% for P, 5.0% for N). Garden soils had a median Bray P value of 80 ppm, far exceeding recommended levels, indicating a buildup and potential loss of P and N. Urban gardens, though only 0.1% of land area, constitute one of the largest inputs of P to the watershed.

Candis M. Hunter, Dana Williamson, Melanie Pearson, Eri Saikawa, Matthew O. Gribble, Michelle C. Kegler · Local Environment · United States (Atlanta)

This study used five focus groups with Atlanta community garden leaders to investigate perspectives on composting, hygiene, and mulching, which are practices to reduce exposure to soil contaminants. Gardeners cited a need for more funding, volunteers, and training. A primary barrier to composting and mulching was concern about contamination of source materials, and participants did not directly link these practices to reducing soil contaminant exposure. Hygiene challenges included concerns about beneficial bacteria, inadequate water access, and limited supplies.

Valerie Chiykowski, Guhan Chendurnathan, Jun S. Lee, Lius Daniel · cIRcle (University of British Columbia) · Canada

This project at the University of British Columbia's Student Union Building (SUB) aimed to reduce contamination in post-consumer organics bins using visual prompts. While the intervention successfully decreased both the percentage weight and level of contamination, the overall weight of compostable waste also decreased post-intervention. The study suggests considering confounding factors like a sustainability fair during baseline data collection and improved bins, and proposes an infrared sensor-based audio prompt system for future efforts.

Sarah Legg · Figshare · United States (Wyoming)

ACRES Student Farm, a University of Wyoming organization, has grown significantly over six years, providing local produce, CSA shares, composting, and educational opportunities. However, the farm suffers from continuous losses in efficiency and acquired knowledge due to the transient nature of its student management and workforce, leading to unsustainable internal functioning. This project aims to develop a management plan and handbook to address these issues and improve the farm's operational efficiency.

Josh Beniston · The Knowledge Bank (The Ohio State University) · United States (Ohio)

An experiment on assessing and managing soil quality for urban agriculture was conducted during the 2011 and 2012 growing seasons on demolished vacant urban lots in Youngstown, Ohio. Soil compaction was identified as a primary constraint, with high bulk density values of 1.79 g cm⁻³ for in-ground plots and 1.55 g cm⁻³ for raised beds. Crop yield data from 2011 showed that both compost-amended and compost + biochar-amended plots had significantly greater crop yields than control plots, with compost + biochar plots achieving the highest harvest index values.

Michael Raleigh · eCommons (Cornell University) · United States (Buffalo)

The City of Buffalo has made progress in accepting urban farming on vacant land, but remains unwilling to take risks in this area. Policies restrict farmers' access to land, long-term security, food diversity (including animals), and sales. To foster urban farming, the City should amend these policies to grant farmers more freedom and could promote farming through a city-wide composting program and a demolition policy requiring vacant lots to be seeded with clover.

Julian S. Yates, Jutta Gutberlet · Environment and Planning A Economy and Space · Brazil (Diadema)

This paper analyzes food waste flows in Diadema, Brazil, through an urban political ecology lens, focusing on integrated organic waste management for composting and urban food production. While presented as a means for positive socioecological change, the process is characterized by conflict and potential exploitation. Broader structural conditions also constrain the system's ability to offer an alternative to existing waste-management models.

Erin Foster West · · United States (Minneapolis)

This study explores the interaction between community gardens and public agencies in Minneapolis and Hennepin County, United States. It identifies that despite a large number of community gardens in the Twin Cities Metro Area, there is no comprehensive city policy for community gardening, making land acquisition difficult as vacant land becomes scarce. The research inventories public policies related to land use, water, and compost specific to community gardens, highlighting the need for public agencies to provide essential services.