Research & reports

Composting Consortium (Closed Loop Partners) · Closed Loop Partners · United States

The largest field test of its kind in North America — 18 months, 10 facilities, over 23,000 units — found that certified compostable packaging breaks down in properly managed compost facilities. Compostable plastics averaged 98% degradation by surface area and fiber packaging averaged 83%, both exceeding industry thresholds (90% and 80% respectively). The market is projected to grow 16% annually.

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.

· BioCycle · United States

A report on EREF's 2023 survey of U.S. landfill tipping fees. The national unweighted average fell to $56.80/ton, a 3% decrease from the prior year and the first decline since 2020, with fees dropping in most regions except the Northeast.

California Department of Resources Recycling and Recovery (CalRecycle) · California Code of Regulations, Title 14 (via Cornell Law) · United States

A California regulation setting the physical contamination limit for compost: material larger than 4 mm must not exceed 0.5% by dry weight, of which film plastic must be no more than 20%. Operators must sample every 5,000 cubic yards.

Closed Loop Partners, Composting Consortium · Closed Loop Partners / Composting Consortium · United States

Closed Loop Partners' Composting Consortium conducted the largest known North American field test of certified, food-contact compostable packaging, analyzing over 23,000 units across nine commercial composting facilities. While roughly 70% of food waste composters already accept such packaging, the report says public data on actual disintegration performance and optimal composting conditions had been limited. Data will feed a public database and the first ASTM field test standard for compostable packaging.

Logan Bowdish, Adalie Duran, Justin Richardson, Eric Vukicevich · Urban Agriculture & Regional Food Systems · United States

In an urban community farm, this study evaluated how crop identity, harvested tissue, and soil factors—including arbuscular mycorrhizal (AM) fungi—affect crop uptake of lead and arsenic. Lead uptake increased with lower soil pH and lower soil phosphorus, greater AM fungal colonization was associated with greater lead uptake, while more fungal storage vesicles related to less arsenic uptake into leaves.

Lila B. Karki, Prem Bhandari · Global Journal of Agricultural Research · United States (Maryland)

This 2022 project collected data from 22 small, socially disadvantaged minority urban gardeners in Maryland to enhance their efficiency. Findings showed farmers operated rationally, cultivating an average of 20 diversified specialty, ethnic, and medicinal crops on 1.2 acres. They employed integrated alley and mixed cropping systems, rainwater harvesting, expanded compost-making, maintained high cropping diversity, and introduced a tier system to mitigate production, marketing, and financial risks.

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.

Tibisay Pérez, Sintana E. Vergara, Whendee L. Silver · Scientific Reports · United States

Continuous micrometeorological mass-balance measurements of greenhouse gas emissions from commercial-scale windrow food-waste composting found emission factors of 6.6–8.8 kg CH4–C and 0.01 kg N2O–N per Mg of wet food waste, for a combined emission factor of 926 kgCO2e per Mg of dry food waste. Composting emissions were 38–84% lower than equivalent landfilling, with a projected minimum net savings of 1.4 MMT CO2e for California by 2025.

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.

Mykl Nelson, Gwynne Mhuireach, Gail A. Langellotto · Urban Agriculture & Regional Food Systems · United States (Oregon)

To characterize residential-scale urban agriculture soils, the authors sampled 27 residential vegetable gardens in two western Oregon cities, distinguishing in-ground beds from raised beds. They found these soils frequently exceeded recommended ranges for many fertility parameters—likely due to routine overapplication of compost, amendments, and fertilizers—with raised beds significantly higher than in-ground beds in carbon/nitrogen ratio, active carbon, and sulfur.

Alexandra Niedzwiecki, Norah Kates, Sally Brown, Kristen McIvor · Urban Agriculture & Regional Food Systems · United States (Tacoma)

This study surveyed 66 community gardens (1,960 plots) in the nonprofit Harvest Pierce County program in Tacoma and Pierce County, Washington, which provides gardeners with land, soil testing, clean soil, compost, water, and education. It found gardens were well-used across the program (mean use intensity 2.26 on a 0–3 scale), with larger gardens and plots used more intensively, and gardens well distributed across income, population density, and racial identity—suggesting the resource-provision model is inclusive.

Margaret Marcy Emerson · Digital Commons - LIU Promoting Scholarship and Creative Work of LIU Students, Faculty, and Staff (Long Island University) · United States

In 2019, an estimated 35% of all food was lost or wasted in the U.S., and organic waste in landfills generates methane, a potent greenhouse gas. Composting significantly cuts the amount of food going into landfills, reducing climate and environmental impacts. Compost enhances soil, reduces the need for chemical fertilizers, improves soil water retention, provides carbon sequestration, and local composting conserves energy and reduces transport emissions.

Carine Borchert Rosa, Daniela Mueller de Lara, Erli Schneider Costa · Revista Eletrônica Científica da UERGS · Brazil (Rio Grande do Sul)

This study at Escola Estadual de Educação Básica Santa Rita in Nova Santa Rita, Brazil, applied a research-oriented teaching proposal to students, focusing on inorganic functions through organic fertilizer production using school waste. Students built a garden, collected waste, produced organic fertilizer, and validated results. The study observed mutual aid among students, developed their intervention capacity, and noted a positive change in their approach to discarded waste like potato peels, banana peels, eggshells, and mate.

Dsouza A., Price G., Dixon M., Graham T. · Sustainability · Canada

Presents a conceptual framework for incorporating composting into closed-loop urban controlled environment agriculture to recycle nutrients from organic waste streams.

Jonnell Robinson, Sarah Brown, Rose Tardiff, Dennis Brady, Jen Pauley, Mable Wilson · Journal of Agriculture Food Systems and Community Development · United States (Syracuse)

Syracuse Grows is an all-volunteer nonprofit organization in Syracuse, New York, dedicated to food justice. The organization hosts an annual "Resource Drive" event each April, mobilizing community resources to support over 25 community gardens and 3 urban farms. During this event, compost, mulch, and manure are transported across the city, transforming previously vacant lots into spaces for nourishment and camaraderie.

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.

Ana Karen Ricaño Ochoa, María de los Ángeles Chamorro Zárate Achamorro · South Florida Journal of Development · Mexico (Xalapa)

An environmental education and communication strategy for integrated organic waste management was applied in the Zipor neighborhood of Xalapa, Veracruz, Mexico. This project aimed to raise awareness and provide training for residents, promote citizen participation in organic waste classification and biological treatment, and install community urban gardens for compost utilization. A total of 30 residents, divided into three groups (representing 5% of the neighborhood's inhabitants), participated in three stages: waste separation workshops, compost module construction, and urban garden installation.

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.

T. E. Freeman, Tiare Saracino, Lynn Barber, Tom Wichman, Esen Momol, Kristina McIntyre, Jacqlyn Rivas, Jennifer Marvin · EDIS · United States (California)

This is a homeowner-facing extension publication from Florida on environmentally friendly ways to enhance soil fertility for vegetables, herbs, and fruit in home landscapes. It describes recycling nutrients on-site or via composting to build productive edible landscapes with less waste, stating that adopting these methods into landscape maintenance builds organic matter and adds nutrients to soil naturally.

Shrestha P., Small G.E., Kay A. · PLOS ONE, 15(4):e0230996 · United States

A study measuring and quantifying nutrient recovery efficiency and loss from compost application in urban gardens. It shows compost often supplies phosphorus far in excess of crop demand, and surplus P can be lost to waterways. The work argues that closing the food-waste-to-compost loop in urban agriculture must be designed for sustainable nutrient management, not just diversion.

Carmen M. Ugarte, John R. Taylor · Urban Agriculture & Regional Food Systems · United States (Chicago)

This study evaluated chemical and biological soil-health indicators at 21 urban-to-periurban sites in Chicago (home gardens, community gardens, institutional farms, and private urban farms). It measured soil fertility, nematode trophic composition and food-web indices, and concentrations of lead, arsenic, and zinc; nematode communities differed by management scale and were likely influenced by soil organic matter and pH. Lead, arsenic, and zinc were below levels of concern, and soil fertility was significantly increased by management, particularly in community gardens and urban farms.

Cassia Silva Santos Góes · Revista Integrativa de Inovações Tecnológicas nas Ciências da Saúde · Brazil

This paper documents the presentation of the “School Garden Project in Bahia” at the International Congress on Technological Innovation in Health Sciences, held from November 15 to 18, 2017, at IFBA SAJ. The presentation highlighted the school's experiences with a social community garden, including resistances, advancements, garden care outside school hours, and the teaching of composting and natural fertilizers using organic compounds.

A. V. Silva, Jamerson Fábio Silva Filho, Dalcimar Regina Batista Wangen, M. L. C. Souza, E. L. Silva · Scientific Electronic Archives · Brazil (Urutaí)

This project at Maria Cândida de Jesus Municipal School in Urutaí, Brazil, engaged elementary students and staff in composting and school gardening to raise awareness about waste reduction, reuse, and recycling. Participants learned about environmental issues, practiced composting with Californian worms, and used the resulting compost to fertilize vegetables in a newly built school garden. The initiative successfully demonstrated student enthusiasm for selective waste collection, composting monitoring, and garden implementation.