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.

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.

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.

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.

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.

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.

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.

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.

Chammi P. Attanayake, Ganga M. Hettiarachchi, Mónica Palomo, Gary M. Pierzynski, Blanca Calderón · ACS Agricultural Science & Technology · United States

The effect of limestone and composted manure on lead (Pb) in vegetables and Pb bioaccessibility was assessed in a contaminated urban garden (total Pb ~200 mg kg⁻¹). Amendments did not affect Pb in vegetables or Pb bioaccessibility. Peeling reduced Pb concentration in radish by half, and removing surface dust reduced Pb in leafy vegetables by 40-50%. Daily Pb intake from consuming lettuce and carrot/beetroot from this garden was approximately 1.5 times higher than the interim reference level proposed by the U.S. Food and Drug Administration.

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.

Hillary A. Craddock, Elisabeth Fost Maring, Stephanie Grutzmacher · African Journal of Food Agriculture Nutrition and Development · Ethiopia

A mixed-methods pilot survey of 21 teachers and parents in Debre Berhan, Ethiopia, investigated household agricultural practices to understand foodborne illness risks. The study found that half of respondents using manure applied uncomposted manure as fertilizer, and many kept multiple animal species. This suggests a high risk of pathogen exposure for children and adults through contact with uncomposted manure and animals.

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.

Cosmos C. Alamanjo, Abimbola O. Adepoju, H. Martin, R.N. Baines · Zenodo (CERN European Organization for Nuclear Research) · Nigeria (Jos)

This mixed-methods study investigated farmers' perceptions, willingness, and capacity to use household sewage sludge as organic resources for peri-urban agriculture around Jos, Nigeria. Farmers were found to use a complex mix of fertilizers and were keen to utilize household sewage sludge for soil fertility, though constrained by accessibility. A critical finding was that household sewage sludge observed in the field is heterogeneous due to its proximity to urban refuse disposal, raising concerns for possible cross-contamination of pollutants and indicating a lack of extension guidance.

Surendra K. Pradhan, Olufunke Cofie, Josiane Nikiema, Helvi Heinonen‐Tanski · Sustainability · Global

This research determined the fertilizer value of sawdust and fecal sludge (SDFS) pellets and compared their effect on lettuce cultivation with other fertilizers in a greenhouse and open field. SDFS pellets, with or without enrichments, resulted in higher saleable fresh weight lettuce yields than commercial compost, poultry manure, mineral fertilizer, or no fertilizer. Open field cultivation yielded more than greenhouse cultivation. While no helminth eggs were detected, some fecal coliforms were found in lettuces fertilized with almost all tested fertilizers, including NPK and the non-fertilized control.

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.

이윤숙 · · Global

Urban agriculture has gained emphasis due to its importance for leisure and recreation in modern society. However, public health may not be guaranteed due to continuous odors from animal compost. Biochar is an amendment that can reduce odors and enhance crop productivity, but this abstract is truncated and does not present specific research findings.

Marta Bożym · Ochrona Środowiska i Zasobów Naturalnych · Poland

A study measuring heavy-metal content (cadmium, lead, copper, zinc, nickel, chromium) in compost and resident earthworms sampled from home composters and allotment gardens in the Opole region of Poland. The compost samples themselves were not contaminated with heavy metals and stayed within Polish legal limits for solid organic fertilizers. However, metal accumulation in earthworms varied by metal: the bioaccumulation factor (BAF) was high for cadmium, lead and zinc, while no accumulation was found for nickel, chromium or copper. The authors conclude that earthworm species native to Poland, such as Eisenia fetida, can serve as potential bioindicators of metals in the environment.

Josh Beniston · The Knowledge Bank (The Ohio State University) · United States (Ohio)

An experiment on assessing and managing soil quality for urban agriculture was conducted during the 2011 and 2012 growing seasons on demolished vacant urban lots in Youngstown, Ohio. Soil compaction was identified as a primary constraint, with high bulk density values of 1.79 g cm⁻³ for in-ground plots and 1.55 g cm⁻³ for raised beds. Crop yield data from 2011 showed that both compost-amended and compost + biochar-amended plots had significantly greater crop yields than control plots, with compost + biochar plots achieving the highest harvest index values.

Mirelys Rodríguez Alfaro, Olegário Muñiz Ugarte, Bernardo Calero Martín, A. Álvarez, Francisco Martínez Rodríguez, Teudys Limeres Jiménez, Mercedes Orphee Montoya, Adriana M. de Aguilar Accioly · DOAJ (DOAJ: Directory of Open Access Journals) · Cuba

This study evaluated the heavy metal content of Cadmium, Lead, and Nickel in organic fertilizers (composts from urban solid waste) and substrates, and their effect on vegetables grown in organoponics in Havana and Guantánamo, Cuba. Composts obtained from unsorted urban solid waste and the substrates prepared from them were found to contain heavy metals, especially Cadmium and Lead, above maximum permissible limits. It was concluded that these products should not be used for food production, as these metals translocate to the edible parts of the cultivated vegetables.

Sally Brown, Ingrid Clausen, Mark A. Chappell, Kirk G. Scheckel, M. Newville, Ganga M. Hettiarachchi · Journal of Environmental Quality · Global

Against a background in which the safety of urban farming has been questioned because of possible contamination in urban soils, this study tested whether high-iron biosolids-based composts could reduce the bioaccessibility of soil lead (Pb) and arsenic (As), using two laboratory incubations and a field trial. Pb and As bioaccessibility were assessed with an in vitro assay, and changes in Pb, As, and Fe speciation were analyzed on select samples using micro-X-ray fluorescence mapping and micro-XANES. A compost with iron added to wastewater-treatment residuals (Fe WTR compost), applied to soil at 100 g/kg, decreased Pb bioaccessibility in both laboratory incubations, though results for As were mixed. In contrast, the composts tested in the field trial (with iron added as Fe powder or FeCl) did not reduce bioaccessible Pb and showed only limited reductions in bioaccessible As; these same composts also had no effect on Pb bioaccessibility in the second laboratory incubation. The study concludes that high-iron biosolids compost is effective at reducing Pb accessibility only for certain types of iron-rich materials.

O. Muñiz, M. Ternero, Álvarez Montero, F. Martínez, T. Limeres, O. Jouber, M. Orphee, Julia Vidan Estevez, B. Calero, F. A. de Alcantara, Adriana María de Aguiar Accioly · Portuguese National Funding Agency for Science, Research and Technology (RCAAP Project by FCT) · Global

This paper situates its topic within the urban agriculture movement, which it describes as having successfully enabled low-input food production in cities, noting that organoponicos — plots focused on producing leafy vegetables and condiment crops in organic substrates — have driven up demand for organic material sources. The title indicates the study addresses the effect of using heavy-metal-contaminated compost on vegetable production, but the available abstract provides only this background context, with no results on contamination or crop impact stated.

J.N. Hogard, Julius N. Fobil, Godfred K. Ofosu-Budu, D. Carboo, Nii‐Ayi Ankrah, Alexander K. Nyarko · · Ghana

This study in Ghana investigated the macro-nutrient content and heavy metal concentrations in solid waste composts to assess their potential for soil fertility amelioration and health implications in urban and peri-urban agriculture. Overall NPK concentration was low, with agricultural waste composts showing higher total N, K, and organic carbon than municipal solid waste (MSW) composts. Heavy metal concentrations for Ni, Zn, Cu, and Cd were generally low and within Australian standards. However, lead (Pb) concentration in mixed MSW composts was significantly high during the dry season, exceeding the Australian limit of 150 mg/kg Pb for unrestricted use. Seasons and composting processes were found to be important determinants of toxic metal concentrations in final compost products.