Research & reports

Stéfanny da Cruz Nóbrega, Lara Cristine Gomes Ferreira · OKARA Geografia em debate · Brazil (Goiânia)

This article presents results from a university extension project between the Federal University of Goiás and elementary school students in Goiânia, Brazil. The project focused on socio-environmental education through an agroecological school garden, integrating theory and practice with didactic sequences on agrarian geography topics like food consumption awareness, socio-biodiversity, traditional knowledge, and soil management. Activities included workshops on vertical gardens and composting, a soil workshop, and field trips, aiming to exchange knowledge on agricultural production forms, agroecology, and food sovereignty, valuing family farming.

Yoshiki HARADA, Thomas H. Whitlow, Nina Bassuk, Jonathan Russell‐Anelli · Frontiers in Sustainable Food Systems · United States (New York City)

This study compared various soil mixes for rooftop farms to assess stormwater retention, yield, and quality of drought-sensitive crops. A 5-week greenhouse experiment cultivated leaf lettuce using an irrigation rate mimicking average growing season precipitation for New York City, comparing five soil mixes made of coconut coir, biochar, and animal manure compost, plus a commercial rooftop farm soil. Three soil mixes showed good yield with water retention rates up to 100%, and drainage nitrogen output levels were less than 13% of current levels at an operational rooftop farm in NYC.

Pai S., Ai N., Zheng J. · Sustainable Cities and Society, 50:101683 · United States

Using Chicago as a case study, this analysis assesses the feasibility of decentralized community composting on portions of public parks in terms of cost and greenhouse gas emissions. It finds decentralized composting delivers outreach, landfill diversion and cost-saving benefits, with an estimated net benefit of about $100 per tonne, indicating the financial viability of a city-wide strategy to compost household food waste locally.

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.

Sally Brown, Ned Beecher · Compost Science & Utilization · United States

This study modeled the carbon benefits and costs of biosolids compost use in King County, Washington. Soil carbon sequestration was highest for use on disturbed soils, such as new housing developments, neglected urban soils, or highway right-of-ways (–1.1 Mg CO2eq per Mg compost), and lowest for use in well-tended yards or other highly maintained landscapes (–0.036 Mg CO2eq per Mg compost). Compost use for tree growth, calculated over a 30-year period, added above-ground sequestration benefits ranging from –1.53 Mg CO2eq per Mg compost for a mature tree grown on a healthy soil to –4.58 Mg CO2eq per Mg compost for a newly planted tree grown on a disturbed site. Assuming a 20 km haul distance, transport costs ranged from 0.005 Mg CO2eq per Mg compost for delivery in a 5 Mg truck to 0.09 Mg CO2eq per Mg compost for pick up in a personal vehicle.

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.

Vergara, S.E., Silver, W.L. · Environmental Research Letters · United States

A study measuring greenhouse gas emission patterns and emission factors from windrow composting of organic waste. The methane emission factor was 1.7 ± 0.32 g CH4/kg wet feedstock, CO2 was 19 ± 3.7 g CO2/kg, and nitrous oxide was below instrument detection limits. Life-cycle emissions, accounting for avoided emissions and carbon sequestration, were negative at −690 g CO2-e/kg, indicating a net mitigation benefit.

Elizabeth A. Miernicki, Sarah Taylor Lovell, Sam E. Wortman · Urban Agriculture & Regional Food Systems · United States (Illinois)

A 2-year field experiment in Illinois compared urban production systems (direct soil, compost-only raised beds, and mixed compost-and-soil raised beds) and fertilizer sources for their effects on growing media, weeds, and vegetable yields. Compost raised beds had higher pH, organic matter, and nutrients and sharply reduced weeds, and the authors recommend raised beds with a mix of compost and soil for urban vegetable production.

Janaina Henrique dos Santos, Júlio César Maestri · Cadernos de Agroecologia · Brazil

This work presents the experience of reapplying the "Revolution of the Baldinhos" Social Technology, which involves managing organic residues and urban agriculture, in Macaiba-RN, Brazil. The project focuses on women collecting household organic waste to produce thermophilic static compost for urban food production and gardening. This method, originating from the UFSC Method, was applied through the Urban Housing Project with Social Technology (MUTS), supported by AACC/RN and Banco do Brasil Foundation, marking its first national application.

Rayssa da Rocha Batista, Aparecida Hurtado Soares, Carolina Simões dos Santos, Henderson Gonçalves Nobre · Cadernos de Agroecologia · Brazil

In Capitão Poço, PA, urban and peri-urban farmers cultivate vegetables for subsistence and surplus sale. The NEA/UFRA/Capitão Poço/PA has supported these farmers by providing information on agroecology principles and building participatory knowledge on sustainable vegetable production technologies. This initiative included three training workshops on agroecological production systems, covering biofertilizer production, composting, and vermicomposting, fostering learning and knowledge exchange.

Rodrigo Vanderlan do Nascimento, Ajibola Isau Badiru, Luiz Agberto Fragoso De Oliveira · REMEA - Revista Eletrônica do Mestrado em Educação Ambiental · Brazil (Maceió-Alagoas)

This study explored the pedagogical possibilities of using a composter for biofertilizer production as an interdisciplinary teaching resource in the school garden of Monte Sinai College in Maceió-Alagoas, Brazil. Employing a qualitative, exploratory research approach with observational data analysis, it identified educational benefits in environmental projects. The process utilized mango tree residues from the school as primary biomass generators for the composter.

Pei Yu · Digital Commons - RISD (Rhode Island School of Design) · United States (New York City)

This research explores waste management in New York City, the world's most wasteful city, seeking ways to bring waste back into the city and connect people with it. Phase I investigates the composition, quantity, and mobility of NYC's waste management, while Phase II focuses on organic waste and the potential of vacant lots in Lower East Manhattan. Phase III proposes a composting park on the East River, engaging residents in various stages of waste management, and aims to connect urban residents to collective waste and the biome's power to transform organic waste into soil, food, and a new life cycle.

Kaitlin Hathaway · Digital Showcase Research, Scholarship, & Creative Works (University of Lynchburg) · United States (Lynchburg)

The Lynchburg College Community Garden at Beaver Point, United States, was established in 2016 by students and faculty to teach sustainable agriculture and enrich soil. In spring and summer 2017, projects included donating produce, promoting pollinators, raising chickens, and composting. The abstract also describes a designed rainwater collection and irrigation system.

Sabine O’Hara, Dwane Jones, Harris B. Trobman · Advances in higher education and professional development book series · United States

The Landgrant College of the University of the District of Columbia operates urban food hubs as the only exclusively urban land-grant university in the United States. These hubs utilize bio-intensive hydroponic and aquaponic systems and green roofs to maximize productivity in small urban spaces, and kitchens serve as business incubators and training facilities. They also promote waste and water reuse through composting, rainwater capture, and green infrastructure, offering training, wellness, and leadership opportunities to UDC students and DC residents.

Rosalie M. Sharp, Daniel J. Brabander · GeoHealth · United States (Boston)

This study assessed lead (Pb) bioaccessibility, transport, and exposure pathways in urban gardens in Roxbury and Dorchester, MA, in partnership with The Food Project, which brings local farmers into the research. Compost had lower total Pb, lower gastric Pb solubility, and less fine-particle resuspension than soils, with a mean bioaccessible Pb of 265 mg/kg—nearly an order of magnitude lower than soils. Across all matrices, grain sizes under 37 μm held a disproportionate share of bioaccessible Pb, whose isotopic composition pointed to leaded gasoline and leaded paint.

Maia G. Fitzstevens, Rosalie M. Sharp, Daniel J. Brabander · Elementa: Science of the Anthropocene · United States (Boston)

To support urban agriculture and limit childhood lead exposure from resuspended urban soils, this study measured bulk and bioaccessible lead in five types of compost used in Boston urban gardens. Different feedstocks showed unique geochemical fingerprints; bulk lead in compost was a fraction of that in urban soils, yet the bioaccessible fraction exceeded the IEUBK model's default parameters. Based on the observed bioaccessibility, 170 mg/kg total lead in compost yields the same bioaccessible lead as the model predicts for the 400 mg/kg EPA soil benchmark, so risk assessments should treat compost as an urban matrix.

Brown S.L., Chaney R.L., Hettiarachchi G.M. · Journal of Environmental Quality, 45(1):26-36 · United States

A review examining the risk that urban soil lead poses to urban agriculture. It concludes that adding compost, organic matter and phosphorus improves soil properties and reduces both the bioavailability of soil lead and fugitive dust, so urban agriculture is unlikely to raise children's blood lead. The findings support the safety of compost-centred soil management in urban gardens.

Blake Baldwin, Kathleen Koenig, Andries Van der Bent · The Science Teacher · United States

This article describes a partnership between an urban, Midwestern STEM high school, a local university's Engineers Without Borders (EWB) chapter, and a nonprofit organization. In spring 2014, an engineering design unit was developed for high school juniors in a Principles of Engineering course to update compost bins for a community garden. The unit integrated science content with engineering practices, aiming to help students understand conservation, learn the science behind composting, and design effective compost bins to meet the client's needs.

William Kort · UWM Digital Commons (University of Wisconsin–Milwaukee) · United States

This study developed a framework for life cycle environmental assessment of urban organic waste utilization in urban agriculture, specifically fruit and vegetable production. Results suggest that a full "urban nutrient cycle" offers significant environmental benefits, including meeting up to 70% of vegetable and 17% of fruit consumption needs in Northern and Eastern U.S. cities, with potential water savings of 10-17% of annual domestic use. Optimizing resource recovery through source separation leads to 1-2% lower wastewater generation and up to 44% greater phosphorus recovery, while overall energy and emissions benefits are 1-2% of a city's annual totals.

Talita Slota Kutz, Fernanda Daniela Bandelero, Jéssica Cardoso, Thiago de Olivera Vargas · · Brazil

This work describes a 16-hour theoretical-practical workshop conducted in a settlement in Peritoro-MA, Brazil, during the "Operacao Velho Monge" of Project Rondon in 2014. The workshop aimed to disseminate agroecological horticulture through the implementation of a pilot community garden project with drip irrigation and composting systems, facilitating learning for both the settlement community and participating students.

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.

Joshua W. Beniston, Rattan Lal, Kristin L. Mercer · Land Degradation & Development · United States (Youngstown)

In Youngstown, Ohio, this study measured soil and plant responses to organic-matter amendments made from yard wastes and to raised beds on vacant lots where houses had recently been demolished. Two years after application, the amendments significantly improved soil physical, chemical, and biological properties and increased vegetable yields, with a soil quality index comparable to rural agricultural soils. The results indicate urban agriculture can be productive on vacant land and that yard-waste amendments can restore degraded urban soils.

Angela Y. Y. Kong, Cynthia Rosenzweig, Joshua Arky · HortScience · United States

This study evaluated the effects of organic and inorganic nitrogen (N) inputs on N dynamics within substrate typically used on rooftop farms during an 8-week greenhouse experiment in the United States. Substrate without added N inputs (control) was compared with synthetic fertilizer and three organic N inputs: composted poultry manure, municipal green waste compost, and vermicompost. Few differences in N cycling and yields were found among treatments receiving organic N inputs, despite differences in carbon-to-nitrogen ratios. Crop yields from the synthetic fertilizer and municipal green waste compost treatments were higher than other organic N input treatments. Inorganic N levels in the synthetic fertilizer treatment decreased from 129 mg N/L to 113 mg N/L, while control and organic N input treatments showed nearly 10-fold decreases from 79.5–117.8 mg N/L to 12.8–16.6 mg N/L over 8 weeks. The greatest losses of ammonium and nitrate via leachate were measured from the synthetic fertilizer treatment.

Geneviève S. Metson, Elena M. Bennett · Elementa Science of the Anthropocene · Canada

A study of Montreal, Canada, examining the potential and barriers for phosphorus (P) recycling through organic waste, noting that currently only 6% of P in Montreal's waste is recycled. Combining semi-structured interviews with 19 key stakeholders, participant observation over more than 1.5 years, and document review, the study identified key barriers and facilitators to achieving a high level of organic waste recycling through composting. A provincial law mandating 100% recycling of organic matter was found to have great potential to facilitate increased P recycling, but this potential is inhibited by a lack of shared vision about the roles of government, the private sector, and citizens in producing high-quality compost, along with cultural inertia, lack of knowledge, and lack of infrastructure. Urban agriculture, which benefits from strong citizen support and is both a consumer and producer of compost, could help overcome some of these barriers, but limited access to garden space and training, and diversity in the fertiliser qualities gardeners want, somewhat limit this potential.

Tainã Coelho Quevedo, Anilton Squena de Oliveira, Lauren Machado Gayeski, Marcelo Pereira de Barros · DOAJ (DOAJ: Directory of Open Access Journals) · Brazil

Through Universidade Feevale's participation in Brazil's Projeto Rondon, workshops presented concepts and methodologies for developing community gardens and reusing organic waste and rainwater in two locations in Maranhao state. Three lectures were given and four community gardens, four composters, and two cisterns were built across four municipal schools, training 97 people. Environmental multipliers were trained through active community participation, and alternative cost-reduction techniques were made available for economically disadvantaged regions.