Research & reports

Sanchez A. · Frontiers in Chemical Engineering · Global (review)

A perspective article synthesising scientific knowledge on decentralized (home and community) composting of food waste, discussing its role relative to centralized systems in urban organic waste management.

Shefaza Esmail, Maren Oelbermann · Frontiers in Soil Science · Tanzania (Mwanza)

This study investigated farmer perspectives and compost application for soil management in urban agriculture in Mwanza, Tanzania. Semi-structured interviews with 34 urban farmers revealed concerns about climate change and unpredictable rain, with 82% desiring soil improvements. A field trial showed that organic amendments (poultry manure and food waste compost) improved soil water holding capacity by 14-19% and enhanced microbial biomass 1.7-4 times compared to inorganic nitrogen fertilizer, with comparable crop productivity.

Eleano Rodrigues da Silva, Sônia Sena Alfaia, Marta Iria da Costa Ayres, S. G. A. de Sousa, Robert Corrêa Rodrigues · Concilium · Global

This study investigated the production of liquid humus (HL) using different solvents and proportions for use in urban and peri-urban afforestation and agriculture. Nutrient content and concentrations, yields, and the odor and appearance of the residue were analyzed. Results indicated that the odor in all HL samples was very mild, practically odorless, allowing their use in urban areas. From the chemical compositions of the analyzed products, it was inferred that HL has potential for use in urban agricultural practices, possibly contributing to improving soil cation exchange capacity (CTC).

José Hilario Rocha Araujo, A. Pando-Bahuon, C. Hartmann, H. Aroui-Boukbida, Thierry Desjardins, Thomas Z. Lerch · Frontiers in Ecology and Evolution · Global

This study evaluated the possibility of growing green vegetables on soils made from excavated deep horizon soils and green waste compost. Over three seasons, the effects of different amounts of compost (10, 20, and 30%) and the addition of earthworms (Lumbricus terrestris) on the production of lettuce, arugula, and spinach were tested in situ. The results demonstrated that it is possible to reuse urban mineral and organic wastes to engineer soils adapted to agriculture. Higher doses of compost significantly increased plant biomass, especially when earthworms were introduced.

· Middle East Journal of Agriculture Research · Egypt

Two experiments were conducted in 2020 and 2021 on a rooftop garden in Giza, Egypt, to investigate the effect of substrate type and fertilizing programs on molokhia and spinach yield and nitrate content. Substrate S1 (50% perlite: 50% peat moss) was found more suitable for high yield. While chemical nutrient solution (CNS) alone resulted in the highest yield, the combination of S1 and CNS followed by compost tea for 5 days before harvest (CNS+5) was most suitable for high yield with lower nitrate accumulation.

Anithadevi Kenday Sivaram, Logeshwaran Panneerselvan, Aravind Surapaneni, Elliot Lee, Kurunthachalam Kannan, Mallavarapu Megharaj · Environmental Advances · Australia

This study assessed 19 commercially available composts, garden soils, and potting mixes in Australia for 38 per- and polyfluoroalkyl substances (PFAS). Total PFAS concentrations ranged from 1.26 to 11.84 µg kg−1 (dry weight), with total perfluorinated carboxylic acids (ƩPFCAs) being higher than perfluoroalkyl sulfonic acids (PFSAs). The total oxidizable precursor assay (TOPA) showed an increase in short-chain ƩPFCAs (0.48 to 7.63 µg kg−1) in composts and potting mixes, indicating transformation of PFCAs precursors. The measured concentrations of short-chain PFCAs in soil substrates have the potential to contribute to plant uptake and food chain transfer of PFAS to humans.

José Luis Villalpando, Daniel Francisco Chi-Maas, Itzel López‐Rosas, Víctor Ángel Aquino-Luna, Jesús Arreola-Enríquez, Julia Cristel Alcudia-Pérez, Gilberto Matos-Pech, Roberto Carlos Gómez-García, Jesús Froylán Martínez-Puc, William Cetzal‐Ix · Agriculture · Global

This study evaluated a backyard system using 50cm × 50cm pinewood boxes for maize and peanut over nine months. Approximately 213 kg of organic residues were converted into 300 kg of mature compost, and plant development was compared between compost and control conditions. Correlation analyses of morphological properties showed that nutrient effects were positively associated with crop morphology, with maize yields of 9 kg/m2 in compost conditions and 6.6 kg/m2 in control, and peanut yields of 184 g/m2 in compost and 73 g/m2 in control.

Mamdouh M. Arafa Arafa, Sabry M. Shaheen, A.M.K Mansour, M. F. A. Ahmed · International journal of Environmental Studies and Researches · Egypt

Over the 2020 and 2021 growing seasons at Sadat City farms (Cairo–Alexandria Desert Road, Menoufia Governorate, Egypt), this study tested the effect of compost application on root-rot disease management and tomato productivity. Rhizoctonia solani and Sclerotium rolfsii were isolated from rotted tomato plants as the main pathogens causing root rot and damping-off, which reduced yield. Adding plant residue, cow manure, or compost (plant residue plus cow manure) to soil before transplanting, at a rate of 1.2 kg/m², significantly reduced disease incidence and raised plant survival compared with untreated controls in both seasons. Compost — a tomato-rich organic fertilizer — applied at 1.2 kg/m² produced the largest reduction in disease incidence and the largest increases in vegetative growth (plant height, branches per plant, leaves per branch), yield parameters, flavonoid content, and total phenol content across both seasons; no clear significant differences were found between the plant-residue and cow-manure treatments in plant growth characteristics.

Kyle Richardville, Dan Egel, Andrew Flachs, Amit K. Jaiswal, D.J. Perkins, A. W. Thompson, Lori Hoagland · Urban Agriculture & Regional Food Systems · Global

A two-year field trial tested whether amending degraded urban soils with locally made leaf-mold compost could improve soil chemical and biological properties and support the survival of a plant-growth-promoting, disease-suppressive microbial inoculant (Trichoderma harzianum T-22) in tomato (Solanum lycopersicum) production. Compost-amended plots showed markedly higher active soil organic matter and marketable fruit yield in both years, lower foliar disease severity in year two, and reduced transplant-stress deaths from T-22 inoculation in one cultivar, but the authors caution that all composts must be tested for heavy metals or pathogens and that overapplication can reduce crop health.

· Sensors · Global

Optimizes bokashi composting of household organic waste in a smart composting bin, fermenting banana peels with EM-1 brans over 14 days while sensors log temperature, humidity and moisture.

Leena Erälinna, Barbara Szymoniuk · Sustainability · Finland

This article presents an experimental project in Turku, Finland, aimed at implementing a circular food system in sustainable urban farming. The project had two objectives: reducing food waste in Turku University Campus restaurants and supporting local nutrient recycling by composting food waste for urban farming. The resulting concept, based on two experimental studies, is globally replicable for managing local circular food systems.

A. Varela, Alexandra Sandoval-Albán, Marcela Muñoz, Alfonso Goméz Gómez, Manuel Bogoya, Germán Combariza · Urban forestry & urban greening · Global

This study evaluated the optimal combination of three different modular extensive green roof structures and two types of local substrates (compost and soil + biochar) for Lactuca sativa L. var. crispa (lettuce) growth under tropical climate conditions, measuring physicochemical and biological properties of substrates and plant growth variables over seven weeks under rainy and dry conditions. A monolithic multilayer structure, high Mg concentrations, elevated amounts of 600 μm aggregates, and lower substrate bulk density were linked with higher L. sativa yield, but the specific substrate used was not associated with this result. Some physicochemical and microbiological properties of substrates changed by the experiment's end, with these changes dependent on climatic conditions.

Jemima Japakumar, Rosazlin Abdullah, Noor Sharina Mohd Rosli · AGRIVITA Journal of Agricultural Science · Malaysia (Kuala Lumpur)

A field study in an urban community garden in Kuala Lumpur, Malaysia, investigated the effects of biochar and compost on Amaranthus sp. growth and soil properties. Using a randomized complete block design with five treatments, the combination of biochar and compost significantly increased plant height, leaf count, leaf width, chlorophyll content, fresh and dry weight, soil organic matter, and soil organic carbon content compared to other treatments. This combination showed the best effects in enhancing both soil properties and plant growth.

Corinna Schröder, Franziska Häfner, Oliver Christopher Larsen, Ariane Krause · Agronomy · Global

This pot trial with lettuce plants assessed the fertilizer value of composts derived from urban organic waste. Seven treatments, including food waste vermicompost and thermophilic compost from green waste and human feces, were investigated. Lettuce yield and total uptake of P, K, Ca, and Mg were highest with coir-based vermicompost, while fecal compost resulted in high shoot P and K but lower Ca and Mg uptake. All composts required additional nitrogen for lettuce growth, indicating a need for further research on macronutrient availability and alternative N sources.

Samuel Ken‐En Gan, Ser-Xian Phua, Joshua Yi Yeo, Zealyn Shi‐Lin Heng, Zhenxiang Xing · Methods and Protocols · Global

This study investigated using mealworms and superworms to consume polystyrene (PS) and their frass as plant fertilizer. Researchers found that small amounts of sucrose and bran increased PS consumption by the worms. Superworm frass, in particular, supported better growth and rooting of dragon fruit cacti over a fortnight compared to mealworm frass and control media. These findings suggest worms could offer a zero-waste solution for plastic degradation and urban farming.

Jennifer Jevons · · New Zealand (Wellington)

The work of Kaicycle, an urban farming initiative located on Wellington City Council land in New Zealand, was spotlighted. This initiative aims to help the community by improving awareness of soil health, advocating for food waste minimization, growing produce, and practicing regenerative composting. Kaicycle recycles food scraps from the community, composts using anaerobic microbes, and produces vegetable boxes for sale.

Charles Karani, Eric Obedy Gido, Hillary K. Bett · DOAJ (DOAJ: Directory of Open Access Journals) · Global

This study surveyed 456 urban agro-producer households using an electronically-structured questionnaire to explore informal agro-food waste management and safety measures in low- and lower middle-income countries. Findings showed significant disparities in management and safety practices between participating and non-participating livestock and mixed producers. Waste reduction (86%), utilization (86%), segregation (63%), and composting (58%) were preferred, while disposal (18%) and mixing with salt/dry feeds (24%) were less preferred. Knowledge variables, such as waste sorting and urban agriculture knowledge, had a greater influence on these practices.

Agnieszka Zawadzińska, Piotr Salachna, J. Nowak, Waldemar Kowalczyk, Rafał Piechocki, Łukasz Łopusiewicz, Anna Pietrak · Agronomy · Global

This study investigated the use of compost made from pulp and paper mill sludge, fruit-vegetable waste, mushroom spent substrate, and rye straw as a growing medium for container-cultivated tomatoes. Tomato plants grown in compost-enriched media showed higher leaf greening, more ripe fruit, and increased levels of polyphenols, flavonoids, potassium, calcium, magnesium, and copper compared to controls. Specifically, a medium with 25% compost, 30% high peat, 15% low peat, 20% pine bark, and 10% wood fiber yielded the highest fresh fruit weight, total polyphenol content, and L-ascorbic acid levels.

Dora Neina, Sibylle Faust, Rainer Georg Joergensen · Chemical and Biological Technologies in Agriculture · Ghana

A study in Ghana investigated the potential agricultural value of charcoal and firewood ashes by examining differences in their chemical and mineralogical compositions and the suitability of various extractants for plant nutrients. Charcoal ash had higher pH, EC, and CCE than firewood ash, while firewood ash contained higher levels of As, Cu, Mg, and Zn, and more Mg-rich minerals. Both ashes contained trace elements, but their bioavailability and plant uptake after field application may differ and may not necessarily lead to plant uptake.

Baptiste Grard, Nastaran Manouchehri, Christine Aubry, Nathalie Frascaria‐Lacoste, Claire Chenu · International Journal of Environmental Research and Public Health · Global

A five-year experimental trial quantified the food production potential, soil fertility, and potential contamination of Technosols created from urban wastes for rooftop edible production. The cropping system showed promising results for food production and maintained high fertility. However, a concern was identified regarding the trace metal content of certain edible crops, specifically zinc (Zn) and copper (Cu), although most trace metal levels were below existing norms.

Alak Barman, Swarna Shome · International Journal of Biosciences (IJB) · Bangladesh

An experiment in Gazipur during 2018-19 investigated the effect of six different ratios of soil and organic materials on strawberry and marigold growth and yield for rooftop gardens. Marigold performed best with 1 kg vermicompost for 1 kg soil (T5), while strawberry showed best performance in most parameters under the same treatment. The lowest yield was recorded from 1 kg cowdung for 2 kg soil (T4).

Remigio Paradelo, Antía Villada, María Teresa Barral · International Journal of Environmental Research and Public Health · Global

A two-month pot experiment studied heavy metal transference from five metal-rich urban waste composts and a manure vermicompost to lettuce and Italian ryegrass under controlled conditions. Plant concentrations of Zn, Cu, and Cd increased with their concentrations in compost, while no such relation was observed for Pb. The study found that the ratio of element concentration in plant to compost was much higher for Zn, Cd, and Cu than for Pb, indicating lower bioavailability of Pb.

Dotanhan Yeo, Kouassi Dongo, Adeline Mertenat, Phillipp Lüssenhop, Ina Körner, Christian Zurbrügg · International Journal of Environmental Research and Public Health · Côte d'Ivoire (Tiassalé)

A 2020 assessment of material flows and greenhouse-gas mitigation from decentralized composting, based on primary data from a pilot composting facility in the municipality of Tiassalé, Côte d'Ivoire. Flows were visualised with STAN version 2.6 (Vienna University of Technology) and carbon emission reductions estimated with UNFCCC methods. In 2017 the station processed 59.4 metric tons of organic waste and produced 14.2 metric tons of mature compost — 24% of input mass on a wet-weight basis and 36% on a dry-weight basis. The compost's nutrient content matched published values for sub-Saharan African compost, and heavy metal contamination met both French and German compost standards. Under this composting scenario, 87% of the baseline emissions that would occur under open dumping could be avoided. The study was motivated by the fact that, despite many composting initiatives across sub-Saharan Africa, data on material flows and mitigation contribution were lacking. It rests on one facility and one year of data and does not address long-term operational continuity or markets for the compost produced.

Wielemaker R., Oenema O., Zeeman G., Weijma J. · Science of the Total Environment, 668:1277-1288 · Global

Drawing on a survey of urban agriculture practitioners in industrialised countries, this study characterises how city-derived resources such as compost, food waste and urine are used as fertiliser and how nutrients are managed. It maps the practices and challenges of cycling urban organic waste back to farmland, systematising on-the-ground approaches that link food-waste composting to urban agriculture.

Tibu C., Annang T. Y., Solomon N., Yirenya-Tawiah D. · International Journal of Recycling of Organic Waste in Agriculture · Ga West, Ghana

In Ga West Municipality, Ghana, stack-pile composting of market waste with sawdust, rice straw and swine manure was monitored for temperature, pH, N, P, K and heavy metal concentrations through the composting process.