Research & reports

Nelson Joseph Msacky, Amelia Alfred, Oscar Punguti, Edson Protas, Iddi Mapande, Novatus, Shukrani Phillip, January G Msemakweli · Open MIND · Global

This systematic review aims to synthesize current scientific evidence on the effectiveness of fruit-waste-derived biochar in immobilizing potentially toxic elements (PTEs) in contaminated agricultural soils. It will evaluate how fruit-waste biochar reduces metal bioavailability, plant uptake, and associated human health risks from vegetable consumption. The review also seeks to identify which fruit wastes are used as biochar feedstocks and which biochar properties and production conditions influence immobilization performance, noting that existing research is fragmented.

Sustiyana Sustiyana, Teguh Soedarto · Jurnal Agrosains Karya Kreatif dan Inovatif · Indonesia (Pamekasan)

This study aimed to analyze the influence of access to organic waste, training and education on waste management, government policy support, environmental and social awareness, and business opportunities on income and environmental preservation in sustainable urban farming in Pamekasan. Conducted at Roemah Maggot Nusantara, which uses Black Soldier Fly maggots for organic waste management, the study used multiple linear regression analysis. Results showed that all independent variables simultaneously had a significant effect on income and environmental preservation. However, partially, only environmental and social awareness had a significant effect, while access to organic waste, training and education, government policy support, and business opportunities did not show a significant effect.

Guido Evangelista, Juan David Arosemena, Gaia Stringari, Joan Romanyà, Xavier Gabarrell, Francesco Orsini, Gara Villalba · Agriculture Ecosystems & Environment · Global

This study evaluated the application of 150 t ha-1 of ramial chipped wood (RCW) to degraded peri-urban agricultural soils, comparing its effects on yield, soil health, and greenhouse gas emissions for spinach and sweet potato. Spinach grown with RCW showed the lowest productivity (1.16 – 0.32 kg m-2) among treatments, while sweet potato achieved the highest yield (1.72 – 1.99 kg m-2). High RCW doses initially led to higher CO2 emissions but significantly reduced N2O emissions for spinach (from 0.36 kg ha-1 to 0.07 kg ha-1) and enhanced soil organic carbon and nitrogen stocks for sweet potato, indicating agronomic and environmental trade-offs.

Farooq Ahmad Khan, Faheemullah Khan, Sumati Narayan, Mohammad Amir, Zaffar Mahdi Dar · International Journal of Research in Agronomy · Global

This review synthesizes the concept, design principles, carbon sequestration mechanisms, storage potential, and environmental benefits of carbon gardens, which are multifunctional landscapes designed to maximize carbon sequestration and deliver a wide range of ecosystem services. The article highlights their application in urban and rural landscapes and their integration with carbon-negative farming through practices such as biochar use and compost recycling. It also discusses key challenges related to carbon measurement, establishment costs, land availability, and long-term management.

Serafina Stone, Jeremy Farr, Damian Hine, Yasmina Sultanbawa, S. K. Fyfe · Local Environment · Australia (Brisbane)

This research investigated how 16 members of four urban community gardens in Brisbane, Australia, derive value from their involvement in relation to the food system, using semi-structured interviews and participant observation. The findings indicate that while urban community gardens alone cannot address food security needs, they provide spaces for building community, generating social capital, connecting to nature, and developing food systems education. These benefits are contingent on the gardens' continued existence and primarily extend to those able to participate.

Isabela Thomas Mkude · TANZANIA JOURNAL OF SCIENCE AND TECHNOLOGY · Tanzania (Dar es Salaam)

In Dar es Salaam, Tanzania, the utilization of faecal sludge derived compost (FSDC) by urban farmers remains limited due to farmers' prejudice and hesitance. This study investigated factors influencing FSDC acceptance through a cross-sectional survey of 76 urban farmers. Results indicated that garden location in communal areas, income generation as the primary farming purpose, and accessibility of soil inputs were significantly associated with FSDC acceptance. Farmers' awareness and experience also played important roles.

James Mbugua · African Journal of Climate Change and Resource Sustainability · Global

Biochar is presented as a promising nature-based solution for urban resilience, applicable in soil remediation, stormwater management, and carbon sequestration within green infrastructure. However, its widespread adoption faces significant barriers, including inconsistent feedstock supply, high production costs, limited public awareness, and a lack of standardized quality and safety regulations. The study also identifies a critical need for policies that integrate biochar into urban planning frameworks and incentivize its production and application.

Aminu Zakariyau, Murtala Rabiu · International Journal of Advances in Engineering and Management · Nigeria (Katsina City)

The potential ecotoxicological impacts of municipal solid waste compost (MSWC) on soil, plants, and humans in urban Katsina, Nigeria, were assessed. Analysis of soil mixtures and plant biomass (maize and beans) revealed high phytotoxicity in beans, while maize considered MSWC as phytonutrients. No statistical difference in non-biodegradable substance concentrations in soils and plants was found, and ecological risk index (ERI) indicated low risk; however, Target Hazard Quotients (THQ) suggested a likelihood of non-carcinogenic effects to the ecosystem.

Noémie Régeard · L’Espace Politique · Congo

This article explores the circularity of organic matter streams in Nkayi, an intermediate city in Congo, through interviews and observations. The qualitative inquiry reveals the coexistence of institutional household waste streams, supported by a development project, and informal organic matter streams, identified through intra- and peri-urban agricultural practices. These streams are subject to various socio-territorial, political, and economic tensions.

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.

Yanick Borel Kamga Valerie Njitat Tsama* · Journal of Biodiversity and Environmental Sciences (JBES) · Cameroon (Nkongsamba)

This study assessed the impact of untreated waste from the municipal slaughterhouse in Nkongsamba, Cameroon, on vegetation by conducting floristic inventories at upstream, near, and downstream sites. Twenty-five 100 m2 plots were established at each site, revealing a total of 105 species from 79 genera and 41 families. The downstream site exhibited the highest species richness with 81 species, 70 genera, and 35 families, but these results showed a dominance of ruderal taxa and pollution bio-indicators like Commelina benghalensis and Tithonia diversifolia, reflecting ecological disturbance of the plant environment.

Javier Bayo, Joaquín López-Castellanos, Marta Doval-Miñarro, Sonia Olmos · Scientific Reports · Spain

An ATR-FTIR analysis of 11 commercial compost products found microplastics in every sample, averaging 137.65 ± 6.01 items/kg dry weight and up to 631.14 mg/kg. Eco-labeled composts had significantly lower microplastic abundance, size, and concentration than non-eco products. Microplastic concentration correlated negatively with pH and nitrogen content and positively with organic matter content.

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.

Roopika Sivaraman, Haritha Thulaseedharan Nair, Sharmila Krishnan, Perumal Siddhuraju · Soil and Sediment Contamination An International Journal · India (Coimbatore)

This study analyzed biocompost and water samples from four agricultural nurseries in semi-urban Coimbatore, India, for microplastic contamination using density separation and ATR-FTIR. While physicochemical properties met Indian standards, microplastic fragments (85%) and fibers (15%) were found in two biocompost samples (BC-B and BC-C), identifying PMMA, PP, and EVA polymers. No microplastics were detected in samples BC-A and BC-D, but the findings suggest semi-urban agricultural gardening may contribute to microplastic accumulation in terrestrial environments, potentially harming soil and plant health.

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.

Géant Basimine Chuma, Jean M. Mondo, Adrien Byamungu Ndeko, Etienne M. Akuzibwe, Espoir Mukengere Bagula, Gustave Nachigera Mushagalusa · Discover Sustainability · Democratic Republic of Congo (Bukavu City)

This study investigated the quantity, composition, and disposal practices of domestic waste in Bukavu City, Eastern D.R. Congo. Findings revealed significant challenges in waste management infrastructure and practices, showing that approximately 5% of waste undergoes composting, while 10% is used as livestock feed, 66% incinerated, and 17% buried. Waste management is primarily handled by children (82%), with very limited involvement from non-governmental organizations.

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.

Jaume Vilasís Pamos, Pablo Aránguiz, Stefhania Lozano, Guillermo Palau Salvador · Revista Lecciones Vitales · Spain (Valencia)

This study examines urban agriculture initiatives in Valencia, Spain, which adopt an agroecological approach to promote sustainable practices like composting. While these collective strategies aim for sustainable agricultural models and contribute to food sovereignty, they face significant challenges, particularly regarding access to water. The initiatives also engage in political action and promote equitable organizational models.

Moye Eric Kongnso · International Journal of Environment Agriculture and Biotechnology · Cameroon

A mixed-methods study in the West Region, Cameroon, examined compost use in urban farming through 265 household surveys, 11 in-depth interviews, and one focus group. While compost availability and technical assistance favor its use, small-scale farmers face significant technical, knowledge, financial, institutional, and policy constraints. State extension services prioritize mineral fertilizers over compost, and the current regulatory framework does not encourage compost use, leading to the persistence of traditional practices.

Anne-Kristin Løes, Sebastian Eiter, Tatiana Rittl · Environmental Sciences Europe · Europe

Using soil data from ten peri-urban case farms near Oslo and Bergen, Norway, this study estimated how quickly potentially toxic element (PTE) concentrations would rise in soil under intensive application of compost or digestate from food waste, composted garden waste, or horse and poultry manure applied annually to meet a theoretical carrot crop's nitrogen, phosphorus and potassium demand. Under this intensive fertilization scenario, Norwegian soil quality limits for PTEs would be reached within 20-85 years, faster in soils with more organic matter, with limits reached first for copper and zinc, both essential micronutrients. The urban waste-based fertilizers were also found to be poorly balanced in macronutrients, with rates covering potassium demand leading to high phosphorus and nitrogen surpluses. The study concludes Norway's PTE regulations are stricter than the EU's and do not support recycling organic matter and nutrients from urban waste.

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.

Li Jiacheng · Eco-Business / Dialogue Earth · China

China's mandatory waste-sorting policy, launched in Shanghai in 2019, improved diversion and recycling but created a new problem: overbuilt waste-to-energy incineration capacity. Shanghai diverted 54% of its waste (6.46 million tonnes) in 2021, up from 21% in 2018, while the number of national incinerators grew from 130 in 2011 to 927 by 2023, pushing 2022 national overcapacity to 100.99%.