Research & reports

Oscar Wang, Rosalind Deaker, Floris van Ogtrop · Agricultural Systems · Global

A systematic review using the PRISMA protocol searched for literature on food-waste based hydroponic fertilisers (FWBHF), identifying 6,840 papers with search terms combining "food-waste," "hydroponic," "fertiliser" and "organic," narrowing to 308 papers by title and abstract relevance and ultimately including 37 papers in the final review. The review sought to identify major challenges limiting yield outcomes in food-waste based hydroponic systems, explore conventional and non-conventional improvements, and propose a standardized reporting framework for future research, framed against a backdrop of an estimated 931 million tonnes of food wasted globally in 2018.

Maulia Usni, Melani Fitri · Prosiding Seminar Nasional Pembangunan dan Pendidikan Vokasi Pertanian · Indonesia

Based on a literature review drawing on books, websites and journals, this study examines how urban farming can support agricultural sustainability in West Sumatra Province, Indonesia. Framing sustainability around the availability of natural resources, human resources and environmental quality, it identifies strategies for optimizing urban farming, including microgreens cultivation, hydroponics, aeroponics, vertical cropping systems (vertikultur), and indoor vertical farms.

Richard Morris, Shannon Davis, Gwen‐Aëlle Grelet, Pablo Gregorini · Land · Global

Applying a GIS-based model (ESMAX), this study tests a spatial method called "Agroecology for the City," aimed at maximizing ecosystem services (ES) in outwardly expanding peri-urban development. Agroecological farm system (AFS) parcels of 1 ha and 4 ha were configured within a real-world 200 ha peri-urban residential development to identify arrangements maximizing the supply of three regulating ecosystem services the local community identified as critical, plus multifunctional performance across them. Configurations with AFS parcels interspersed evenly among built-up areas provided the best multifunctionality across the four ecosystem services tested.

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.

Mélanie Douziech, Stefan Mann, Stefan Galley, Jens Lansche · Agronomy for Sustainable Development · Global

Urban agriculture is often associated with sustainable practices, but the diversity of systems classified as urban agriculture and limited information on their sustainability call that link into question. Drawing on 91 scientific papers, a study proposes a holistic classification of urban agricultural systems combining technical, social and economic characteristics, with economic production intensity and the intensity of cooperation among actors as key axes. One end of the scheme covers ground-based, open, socially motivated systems with high cooperation and low production intensity; the other end covers building-integrated, quasi-closed systems with high production intensity. Mapping sustainability claims from the literature onto the scheme associated "urban farming" with job creation, food safety, water savings and higher yields, and "urban gardening" with educational potential, biodiversity improvements and lower yields.

Chengxiang Zi, D. Winterbottom, Juanjuan Liu · Frontiers in Sustainable Food Systems · China

Focusing on a well-preserved village of the Dong ethnic group in southwest China that maintains traditional livelihoods and a local food system, a study used field surveys, interviews and participatory mapping to propose an edible green infrastructure (EGI) model for traditional villages. The model comprises the "rice-fish-duck" cycle as the core of traditional livelihoods, a hierarchical ecological structure of "households-groups-village," and corresponding management models. By theoretically analyzing the EGI of traditional villages shaped over China's millennia-old agricultural civilization, the study aims to inform sustainable food-system and natural-resource-management knowledge, applying it to the construction of bio-districts in rural China.

Priya Singh, Ramakrishna Bora, Asha Devi · International Journal of Bioscience and Biochemistry · India

This study evaluated the effectiveness of integrated nutrient management (INM) in enhancing brinjal (Solanum melongena L.) growth, yield, and soil fertility in urban agricultural settings in Jorhat, India. Given declining soil fertility and over-reliance on chemical fertilizers, INM — combining chemical fertilizers, organic manures, and biofertilizers — was tested as a sustainable alternative using a Randomized Complete Block Design (RCBD) with four treatments (control, chemical fertilizers, organic manures, INM), each replicated three times. Growth parameters (plant height, Leaf Area Index, number of branches) were measured, and fruit yield and quality were recorded at harvest; soil fertility indicators (pH, organic carbon, nitrogen, phosphorus, potassium) were analyzed at the start and end of the study. INM significantly enhanced growth, producing the highest plant height (112 cm), LAI (3.7), and number of branches (6.5). INM-treated plants produced 33% higher fruit yield (25.4 tons/ha) than the chemical fertilizer treatment and 66% higher than the control. Soil fertility improved in INM plots, with increases in soil pH (6.8), organic carbon (1.8%), and nitrogen, phosphorus, and potassium levels.

J.A. Veraart, Cora van Oosten, Vincent Linderhof, Confidence Duku, Wilfred Appelman, A.M.E. Groot, Marjolein Sterk, Ilse Voskamp · International Journal of Water Governance · Global

With water-related problems from climate change threatening the future of food systems in both the Netherlands and Ghana, this comparative case study analyzed rainwater harvesting and wastewater reuse in the Rhine-Scheldt Estuaries (Netherlands) and the Bono East Region (Ghana). The analysis focused on identifying similarities in how experts and stakeholders use spatial information to remove barriers to, or foster enablers of, the uptake of nature-based solutions (NbS) in view of climate change. Both rainwater harvesting and wastewater treatment techniques were found to be available and ready for adoption by farmers and the food processing industry, but their uptake was hampered by multiple barriers ranging from biophysical and technical to social and institutional. Spatial information was concluded to be a potential enabler for NbS adoption if applicable to a wide range of possible solutions for water scarcity in food production, though both case studies showed difficulty making the future spatially explicit, and in both cases the effect on biodiversity of, respectively, effluent water reuse and rainwater harvesting did not play a direct role in stakeholder dialogue.

David Berná Serna, Sara Sama Acedo, Patricia Homs Ramírez de la Piscina · Revista Española de Sociología · Spain

Against the backdrop of the current eco-social crisis, this article analyzes the "eco-transformative capacity" of collective initiatives in three Spanish case studies: neo-ruralization and natural wine production in the Sierra Oeste de Madrid and southern Sierra de Gredos, agroecological supply systems in Catalonia, and community urban gardens integrated into a municipal program in Madrid. The analysis focuses on the motivations, challenges, and limitations agents encounter while practicing sustainable ways of dwelling, producing, and consuming, and on their relationship to public institutional agendas on eco-social transition.

Utis Sutisna, Junun Sartohadi, Nur Ainun Harlin Jennie Pulungan, Ngadisih Ngadisih, YB Praharto, Nurul Hidayati · Prosiding Seminar Hasil Penelitian dan Pengabdian Kepada Masyarakat · Indonesia

A pyrolysis reactor technology (Prosiding Seminar Hasil Penelitian dan Pengabdian Kepada Masyarakat, Indonesia, 2024) converts sorted urban organic waste slurry into biochar using a self-sufficient pressure-control system with automatic temperature control and internal use of pyrolysis gas as fuel, processing waste at 400-500°C. Performance testing on soil samples showed the resulting biochar had 65-70% fixed carbon content with physical and chemical stability suitable as a soil amendment, increased soil cation exchange capacity by up to 30%, and increased soil moisture by up to 15% compared with untreated control soil. The reactor reduced organic waste volume by 50% and the biochar was reported to improve urban agricultural soil fertility and productivity.

Akiko Iida, Toru Terada, Kazuaki Tsuchiya, Tadashi Yamaguchi, Makoto Yokohari · Urban forestry & urban greening · Japan

Using Tokyo — where urban and agricultural land use have long been intermixed — as a case study, mailed questionnaires and in-person semi-structured interviews with urban farmers examined how community-scale composting of urban-forest green waste is integrated into commercial urban agriculture (2024, Japan). About one-third of professional urban farmers still produced compost, mainly from leaf litter, to improve soil quality, and had adapted to urbanization by sourcing leaf litter beyond their own woodlands from neighboring urban forests within a few kilometers, including parks, schools, and shrines. While urbanization has drastically altered the physical landscape, farmers have carried this intangible composting system forward for hundreds of years by retrofitting it, though the study found farmers are motivated by economic rather than environmental reasons. The authors conclude that decentralized composting works effectively in commercial urban agriculture where waste supply and demand sites are geographically close, and call for further research on scaling up waste recycling through urban agriculture.

Mochamad Yusuf · Al-Masharif Jurnal Ilmu Ekonomi dan Keislaman · Indonesia

Focused on agriculture — one of the strongest sectors supporting Indonesia's economy — this descriptive paper (2024) examines the readiness of Central Java Province, the country's third-largest producer of agricultural output, to build a green economy while adopting a nature-conservation blueprint. Using secondary data collected and analyzed into author-formulated recommendations, the paper finds Central Java is pursuing green-economy and circular-economy practice through the agriculture sector via organic crop cultivation, urban farming, farmers markets, and environmentally friendly agricultural-product education, and concludes that maximizing this implementation requires supporting government regulation/legislation together with societal practice.

Victor Crespo de Oliveira, Leonardo França da Silva, Érika Manuela Gonçalves Lopes, Ana Carolina Chaves Dourado, Matheus Mendes Reis, Bruna Nogueira Rezende, Letícia Duron Cury, Cássio Furtado Lima, Fabiane de Fátima Maciel, Silvana Ferreira Bicalho, Ariadna Faria Vieira · · Europe

Noting that global population growth is raising concerns about the sustainability of cities and soils, climate change, and food access and security, and that many urban areas face challenges related to their food supply infrastructure, this paper positions urban agriculture as a potential contributor to food security and income generation for impoverished households, while noting that conventional agriculture contributes to soil erosion and soil/groundwater pollution, and that climate change disrupts animal life cycles and drives species extinction, reducing food availability for humans and other organisms. Within this framing, the paper presents aquaponics as a method integrating urban agriculture for plant cultivation with safe fish production, and reports a project to develop and install an optimized aquaponics system at the School of Engineering, Polytechnic of Porto (ISEP). The soil-less vertical garden was built using two tanks holding approximately 2,000 liters of water, spanning three floors with three planter boxes and more than 120 positions for growing vegetables. Pedagogical activities were also carried out, involving students from Bioresources, Chemical Engineering, Biomedical Engineering, Electrical and Computer Engineering, Mechanical Engineering and Informatics Engineering.

Haochen Zhao, James T. O’Connor, Sarah Zou, Zakaria M. Solaiman, Bede S. Mickan, Nanthi Bolan · Soil Use and Management · Australia

At six community gardens across three soil mapping units — calcareous deep sands, coloured sand and pale sands — in the Perth metropolitan area, Australia, soil samples were compared between cultivated raised beds and adjacent bare ground used as a control. Raised-bed soils showed lower bulk density, higher pH buffering capacity, more available nitrogen, phosphorus and potassium, greater cation exchange capacity, total carbon and microbial biomass than surrounding urban soil, and were estimated to have accumulated 0.55 kg of carbon per square meter (5.5 t/ha) in the top 10 cm, with no significant heavy metal contamination detected in any of the garden soils. The improved soil health and carbon storage were attributed mainly to regular application of compost produced within the gardens.

Bruno Dias Magalhães, D. B. Almeida, Gabriel Mattos Ornelas, Lara Andrade Silva Viana, Flávia de Paula Duque Brasil, Carneiro, Ricardo José, 1955-, Fundação João Pinheiro, Universidade do Estado de Minas Gerais, Universidade do Estado de Minas Gerais, Fundação João Pinheiro, Fundação João Pinheiro, Fundação João Pinheiro · LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) · Brazil

An analysis of the process of building the Participatory Guarantee System (SPG) for organic/agroecological production in the Belo Horizonte Metropolitan Region (RMBH), Brazil. The SPG's construction traces back to 2004, driven mainly by social movements and civil society actors engaged with urban agroecology; in 2018 the Belo Horizonte municipal government initiated the first protocol of intentions to strengthen agroecology in the RMBH, creating an Inter-institutional Support Committee with SPG consolidation as one of its goals. The article traces this articulation trajectory, emphasizing civil society and social movements' role in what it frames as a "peri-institutional" space, examining how the Committee builds capacities as agroecology draws closer to the state, while also questioning how much real autonomy and agency the people who actually produce and sell within this arrangement retain.

Fitta Setiajiati · Cannarium · Indonesia

A community outreach and mentoring program in Kelurahan Mulyaharja, Bogor City, Indonesia, ran from September to October 2021 with members of the KWT Ciharashas women farmers group. After surveys and discussions with local officials, tourism managers and farmer groups, the team introduced rain garden installation and eco-enzyme production as low-cost urban farming methods, building a demonstration plot on farmer-group land. Residents who had not previously heard of rain gardens or eco-enzymes engaged enthusiastically, and the activity produced more optimal land use along with improvements in aesthetics and environmental health.

Antônio Pampana · Revista VérticeFIB · Brazil

This review essay traces the history of urban agriculture in Brazil—from backyard cultivation of Portuguese origin, through its post-industrial decline, to worsened food insecurity during the Covid-19 crisis—and argues that agroecological urban agriculture (AUA) can combine sustainable management with social benefits, increased biodiversity, and diversified food production including unconventional food plants (PANCs). It cites the green infrastructure project in Vitoria-Gasteiz, Spain, and the Oriente corridors project in metropolitan Medellín, Colombia, as examples of AUA in strategic green-infrastructure planning, while noting that AUA remains largely absent from urban public policy.

農林水産省 · 農林水産省 · Japan

Guidance published by Japan's Ministry of Agriculture, Forestry and Fisheries (MAFF) in July 2024, anticipating increased use of biodegradable plastic bags for household food-waste collection. It requires that such bags be removed, or sufficiently decomposed so their breakdown products do not inhibit crop growth, at composting and biogas facilities.

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.

Gemma Nohales, Mike Stinavage · Zero Waste Europe · Europe

The EU mandated separate collection of bio-waste across all Member States from 31 December 2023, but a LIFE BIOBEST survey of 14 Member States found economic, legal/administrative, organisational and technical barriers present in 86-100% of sampled countries. Only 7 of 27 Member States fully met the 2020 recycling targets, and only 9 are on track for the 2025 targets.

Gabin Colombini, Fatima Senouci, Cornelia Rumpel, Sabine Houot, Philippe Biron, Axel Felbacq, Marie-France Dignac · Environmental Pollution · France

A 2024 analysis of archived soils from a long-term field experiment in France that received three urban composts — municipal solid waste compost, biowaste compost, and a sewage-sludge-plus-green-waste compost — over 21 years. Density fractionation followed by oxidation isolated 1,417 coarse microplastic (CMP) particles, identified by Py-GC/MS; different compost types produced different accumulation levels, and CMP content in soil rose over time. After 21 years the measured number of CMP particles matched estimates derived from compost inputs, but the measured mass did not for any of the three composts, which the authors attribute to biotic transport or to weathering and fragmentation making particles smaller. No difference in temporal pattern was found between films and fragments. The value of the study is long-term evidence that returning urban organic matter to soil also imports plastic; note that the site is farmland, not a city garden, so the figures cannot be transferred directly to citizen composting.

Daniel González, Raquel Barrena, Javier Moral-Vico, Ignacio Irigoyen, Antoni Sánchez · Waste Management · Spain

A 2024 study that measured methane and nitrous oxide (the main greenhouse gases), ammonia, volatile organic compounds (VOCs) and odour from several operating community composting sites in Spain treating kitchen waste, leftovers and household biowaste. Greenhouse-gas emission rates ranged from 5.3 to 815.2 mg CO₂eq per kg volatile solids per day and odour rates from 69.8 to 1,088.5 odour units on the same basis; both fell as temperature and biological activity declined with composting progress, and both were generally lower than rates reported for open-air full-scale composting plants. VOC families were most diverse in the early composting phases, while terpenes — limonene, α-pinene and β-pinene — were the most abundant throughout. The authors start from the observation that scientific data on gaseous emissions from community composting are scarce, which means that arguments about odour nuisance to neighbours have until now lacked measured reference values.

Benedicta Yayra Fosu-Mensah, Nathanael Nii-Odai Laryea, Daniel Darko, Michael Mensah · Heliyon · Ghana (Accra)

In the Greater Accra Metropolitan Area of Ghana, which generates about 2,291 tonnes of municipal solid waste daily (roughly 14% plastic), researchers analysed two municipal solid-waste composts, two dried sewage sludges and a reference soil with five replicates each. Microplastic loads were highest in sludge 1 at 4,316 ± 968 particles/kg, followed by compost 1 at 3,572 ± 1,196, compost 2 at 3,104 ± 418 and sludge 2 at 2,024 ± 562, against 232 ± 62 in the reference soil. Polyethylene, polyester and polypropylene dominated. The results show that returning urban organic waste to soil also carries microplastics into soils and crops. Limitations: only five sampling sources, and FTIR polymer identification applied to a 10% subsample.

Agência Senado · Agência Senado (Senado Federal) · Brazil

An Agência Senado article reporting that Law 14,935/2024, sanctioned on July 26, 2024 and published in the official gazette on July 29, 2024, created Brazil's National Policy on Urban and Peri-urban Agriculture (PNAUP). The law defines urban and peri-urban agriculture as farming and livestock activity integrated into the urban ecological and economic system, and lists seven objectives including expanding food security for vulnerable urban populations, occupying idle urban spaces, generating alternative income, linking production to public procurement, promoting family labor and cooperatives, encouraging agroecological production, and spreading organic-waste recycling.