Research & reports

Santropol Roulant · Santropol Roulant · Canada

Santropol Roulant's rooftop farm in Montreal's Plateau neighbourhood combines intensive garden beds with container gardening and keeps beehives. Produce grown there feeds the organization's meals-on-wheels kitchen, and kitchen scraps are composted in the basement and returned to the rooftop farm, forming a closed food-waste loop.

U.S. Environmental Protection Agency (EPA) · U.S. Environmental Protection Agency (EPA) · United States

This EPA page explains composting: food waste is responsible for 58% of landfill methane emissions and makes up 24.1% of municipal solid waste. Of the 66.2 million tons of food waste generated in the US in 2019, only 5% was composted. Compost adds organic matter and boosts soil microbial diversity, reduces reliance on chemical fertilizers and pesticides, and — because it is typically processed near where it is generated — supports local economies.

· Wikipedia · Global

The Wikipedia article on compost describes it as a mixture used as plant fertilizer that improves soil's physical, chemical and biological properties, made by decomposing plant/food waste and manure. It requires four elements — carbon, nitrogen, oxygen and water — with an optimal carbon-to-nitrogen ratio of about 25:1. About 20% of landfill waste is compostable material such as food, and composting reduces methane emissions compared to landfilling organic material.

· Wikipedia · South Korea

This Wikipedia article on recycling in South Korea (the URL 'Food_waste_in_South_Korea' redirects here) describes a pay-as-you-throw system requiring households to buy designated bags for general waste separate from food waste. The food-waste recycling rate rose from 2% in 1995 to 95% by 2013. Per-capita food waste generation exceeds 130 kg/year, and RFID-enabled smart bins reduced food waste by 47,000 tonnes over six years. South Korea's overall recycling rate reached 59% in 2013, the second-highest among OECD countries; daily household waste fell from 1.3 kg (1994) to 0.94 kg (2013) while the recycled share rose from 15.3% to 83.2%.

· Wikipedia · Taiwan

This Wikipedia article on waste management in Taiwan describes a recycling programme that began in 1989 following a 1987 amendment to the Waste Disposal Act, with the 3R Foundation established in 1994. There are 33 recyclable items across 13 categories; raw food waste is processed into fertilizer for farmers while cooked food waste is converted into livestock feed. As of August 2023, 25 large-scale incineration plants operate, 22 publicly owned (5 publicly operated, 17 privately operated) and 3 privately owned and operated. In 2016, 76.8% of fly ash from coal-fired power plants (1.703 million tons) was reused in construction.

· Wikipedia · Global

A Wikipedia article on terra preta, a fertile anthropogenic dark soil found across the Amazon Basin, formed between 450 BCE and 950 CE and rich in low-temperature charcoal and pottery shards. It notes black carbon content reaching up to 9% (versus 0.5% in surrounding soils), depths of up to 2 meters, a regeneration rate of about 1 centimeter per year, an estimated coverage of 0.1-0.3% (6,300 to 18,900 square kilometres) of the Amazon Basin, and modern biochar-based attempts to recreate it.

· Wikipedia · Global

Soil is a complex three-phase system of minerals, organic matter, gases, water, and organisms that supports plant growth and soil life. A typical soil is about 50% solids (45% mineral, 5% organic matter) and 50% pore space, with microbial density around 10^8 organisms per gram and pore-space CO2 concentrations 10 to 100 times atmospheric levels.

· Wikipedia · Global

Soil compaction is a geotechnical process that removes air between soil particles under stress, increasing density. It is essential as a support layer in construction but reduces water infiltration and root growth in agriculture. The degree of compaction is assessed relative to maximum dry density determined by tests such as the Proctor test; the article presents no specific numeric data.

Gao, Si, Burce, Katrina, Smith, Laney, Espinoza, Nina, Melbourne, Alfred · Frontiers in Soil Science · 米国（カリフォルニア州ウェスト・サクラメント）

Urban agriculture soils are commonly amended with compost, yet how such systems respond functionally to biochar across application rates is poorly understood. In a field experiment at Three Sisters Gardens (West Sacramento, CA, USA), biochar was applied at 0, 10, 20 and 30 t/ha to compost-amended plots under corn and squash, and late-season soils were analysed for physical, chemical and biological indicators. Intermediate rates (10–20 t/ha) improved aggregate stability and increased soil respiration; the highest rate (30 t/ha) produced the strongest biological responses, including higher microbial biomass, fungal:bacterial ratios and extracellular enzyme activities in nitrogen and phosphorus cycling. Soil pH and cation exchange capacity did not differ significantly among treatments. Regression analyses indicated nutrient availability was more strongly associated with microbial indicators than with bulk soil chemistry, consistent with microbial mediation of biochar-associated nutrient dynamics, and the patterns held broadly across both cropping systems.

· Frontiers in Sustainable Food Systems · Spain (Barcelona)

A study analysing both the agronomic and the organisational dimensions of Barcelona's community gardens, examining empirically how citizen-led urban gardens are managed and run.

· Frontiers in Sustainable Food Systems · Global

A thematic review synthesising global trends, innovations, governance frameworks and pathways to sustainability in urban agriculture, mapping the field's current state and future directions including citizen participation, policy support and environmental challenges.

Liu Q., Chen T., Zhang N., Lin Z., Ye Z., Jiang K., Gao Y., Guo Y., Weng A. · Energy (Elsevier), 320:135191 · China (Yangtze River Delta)

A quantitative assessment of rooftop agrivoltaics (RAV) — co-locating solar PV and crops on building rooftops — against the SDGs. For the Yangtze River Delta urban agglomeration (~10,720 km² of rooftops) it estimates ~93.1 TWh/year of electricity (6.3% of regional demand), ~43.6 Mt/year of lettuce, large job creation, and ~127 Mt/year of CO2 reduction, positioning RAV as a multifunctional urban land-use that pairs 'zero food miles' food production with clean energy.

Zhang Y., Chen T., Gasparri E., Lucchi E. · Sustainability (MDPI), 17(2):666 · Australia (Sydney)

Proposes a modular agrivoltaics building envelope that physically integrates thin-film PV and hydroponic farming into the building skin itself, rather than treating solar and agriculture as separate systems. Using a circular design approach with multi-objective optimization of energy, light, water and structure (case study: Sydney), it extends food-plus-energy production from rooftops to walls and facades, highlighting space-utilization and system-integration gains for net-zero urban architecture.

Wilkens J., Mombo S., Dumat C. · Urban Science · France (Toulouse)

Examines 11 years of collective urban gardens in the Toulouse region through the lens of global health—encompassing human well-being, soil health, and interspecies interactions—as a driver of agroecological transitions among gardeners.

Otieno J.A., Omia D.O., Amwata D.A. · Frontiers in Sustainable Food Systems · East Africa (Kenya)

Evidence-based study demonstrating how vertical gardening (particularly sack farming) in Kibera's informal settlements underpins household food security. Shows how stacking soil-filled sacks vertically enables vegetable production in space-constrained environments, serving as a solution to chronic hunger.

Ranalli et al. · Journal of Applied Ecology · Global (urban ecosystems)

2025 research on how urban agriculture and urban planning enhance pollinator habitats in changing landscapes. Urban environments offer benefits to pollinator communities: lower pesticide use, greater variety of floral resources, and increased landscape heterogeneity. Urban agriculture serves as a pollinator reservoir and source area for adjacent rural regions, contributing to food security, poverty alleviation, and pollinator conservation.

Irigoyen I., López M., Orden L., Moral R., Nogués I., Bustamante M.Á. · Agronomy · Europe (urban agriculture focus)

June 2025 study examining how decentralized and community composting are emerging as novel scenarios favoring localized management and valorization of organic waste streams. Supports organic waste reduction at community level and nutrient cycling for urban agriculture fertilization, offering alternatives to centralized composting.

Shimelis G., Kim D., Yimer F., Tadesse M. · Science of The Total Environment · Africa (Ethiopia)

2025 study estimating compost production potential from municipal organic waste and human excreta in Addis Ababa, Ethiopia, with projections through 2050. Quantifies economic benefits (compost sales, fertilizer cost reduction), soil carbon sequestration, and greenhouse gas mitigation. Demonstrates feasibility of organic waste-to-compost systems for urban agriculture in African cities.

· Frontiers in Sustainable Food Systems · North America (Sacramento, California, USA)

Field research conducted at two urban farms in Sacramento, California, USA. Investigates effects of locally produced compost and biochar amendments on soil health and plant nutrient uptake. Demonstrates feasibility of combining sustainable resource cycling with crop productivity in community-based urban agriculture systems.

Thompson, R., Climate & Food Security Research Initiative · Agriculture · Global

Analyzes urban agroecology as a key strategy to build climate-resilient communities and strengthen urban food systems. Examines multifaceted impacts of community-based agricultural practices on biodiversity conservation, local food security, and climate adaptation. Includes comparative case studies from Global South and Global North perspectives.

Emory Walker, Mara Welty, Emma Creviston, Jacob J. Adler · Urban Agriculture & Regional Food Systems · United States (Lafayette)

This project examined how straw cover affects the soil microbiome of a community garden, using EcoPlate carbon-source utilization analysis and 16S rRNA sequencing on samples from the Erie Street GrowLocal community garden in Lafayette, Indiana. Straw cover increased soil moisture content and significantly increased bacterial alpha diversity, with a shift toward carbohydrate preference, though beta diversity showed no difference between conditions. The authors conclude that straw coverage can improve soil microbial biodiversity and moisture, potentially benefiting yields and food quality for communities.

Leigh Whittinghill, Megan Goins, Shawn Lucas · HortScience · United States

This study examined how two urban agriculture production systems (raised beds and container plots) and four nutrient-management treatments (conventional fertilizer, organic fertilizer, peat-and-compost plus organic fertilizer, and peat-and-compost only) affected yields of relay-cropped leafy greens across the 2018–2019 seasons. Significant differences between systems and treatments were few and inconsistent, but results suggest small plastic-pool containers are suitable for urban greens production and tentatively support organic fertilizers and compost as a nutrient source.

Estenia Ortiz, Adriana Mayr Mejia, Emma Borely, Liam Schauer, Lena Young Green, Maya Trotz · Sustainability · United States (Tampa)

Motivated by a community's desire to co-locate community gardens with stormwater pond spaces, this study monitored water quality of a 23.4-hectare stormwater detention pond in East Tampa, Florida over one year and compared it to US EPA reuse recommendations and water quality criteria. pH and conductivity were acceptable for irrigating crops and heavy metals were below maximum reuse levels, but E. coli concentrations exceeded irrigation requirements and synthetic organic compounds exceeded human health criteria.

· Sustainability · China (Chongqing)

A life cycle assessment of a large industrial aquaponics system in Chongqing, China, evaluating environmental performance and identifying optimization strategies.

· International Journal of Environmental Science and Technology · Global

Proposes a household-scale vermicomposting bin using Perionyx excavatus to both treat domestic organic waste and grow vegetables; adding a ventilation pipe improved performance.