Research & reports

Veronika Hansen, Franziska Häfner, Bianca Messmer, Luca Bragazza, Carsten Tilbæk Petersen, Jakob Magid · Agriculture Ecosystems & Environment · Europe

Using a long-term field trial (the CRUCIAL experiment) running for more than 20 years in Denmark, this study compared the long-term effects of bio-based fertilizers (BBFs) — compost, sewage sludge, cattle slurry, and human urine — against conventional mineral NPK fertilizer on soil physical, chemical, and biological properties. Mineral NPK fertilizer supported crop productivity and improved certain soil properties but did not deliver the broader soil health benefits of organic amendments; compost and sewage sludge notably increased soil organic carbon, cation exchange capacity, porosity, water content at field capacity, and microbial activity while reducing bulk density and clay dispersibility. Human urine produced a nitrogen fertilizer effect on crop yield comparable to NPK, but showed a higher sodium adsorption ratio than NPK and a negative trend in bulk density (though values stayed below critical thresholds), indicating a need for complementary organic matter input, and carbon-rich bio-based fertilizers reduced crop production per unit of nitrogen applied.

Alex Axinte, Carmen Rafanell, Bogdan Iancu · Environmental Sociology · Europe

This study investigates the persistence of "gardening by the bloc," an informal urban gardening practice in the green spaces of collective housing districts in post-socialist Bucharest, Romania. Often dismissed in public discourse as a leftover of socialist-era survival strategies, the research instead reconsiders it as an everyday social interaction that supports communities amid urban transformation. Drawing on Tsing and De Angelis, the study frames the practice as a local form of "latent commons" reflecting broader socio-political shifts in a post-socialist city. Based on qualitative research, it documents how residents use, adapt and manage these green spaces and their relations with institutional actors under increasingly neoliberal governance, arguing that the overlap between a market-oriented regulatory project, inherited socialist structures, and collective spatial practices has shaped a distinct way of living together. As an emerging form of urban commons, gardening by the bloc can sustain shared communal practices against an increasingly individualized society and lay groundwork for bottom-up regeneration of housing estates, but the article also reveals contradictions inherent to latent commons, including internal tensions and ambiguities.

Johanna Bock, Márcio Zamboni Neske, Martin Krauß, Andrea Dombrowski, Jörg Oehlmann · Environmental Sciences Europe · Europe

Focusing on small water bodies in private urban gardens, this study examined whether chemical pollution limits insect diversity, given that gardens make up a significant share of urban green area and can serve as important habitats and stepping stones for insects, while pesticides, fertilizers and chemical run-off from building materials can strongly affect habitat quality and insect biodiversity. Garden pond toxicity was assessed using in vitro and in vivo methods and chemical screening. Of 17 ponds examined, only one water sample and one sediment sample were found non-toxic in a bioluminescence assay with Aliivibrio fischeri. Enhanced dioxin-like activity was measured in seven water and ten sediment samples using a reporter gene assay with Saccharomyces cerevisiae, and most water extracts showed mutagenic potential in the Ames fluctuation assay (Salmonella typhimurium strains YG1041 and YG1042), while most sediment extracts were not mutagenic. Increased larval mortality of Chironomus riparius occurred in five water-sediment systems built from pond samples, correlating positively with in vitro water toxicity and with concentrations of benzothiazole derivatives measured by LC-HRMS, likely originating from EPDM rubber pond liners. Substance composition differed significantly between house and allotment gardens, with higher concentrations measured in allotment ponds. The study concludes that chemical pollution in private urban gardens may have been underestimated to date, and that pond toxicity can severely affect insect populations, warranting further study.

Yu Huan, Steffen Nijhuis, Nico Tillie · Journal of Cleaner Production · Europe

Using Rotterdam as a case study, researchers combined machine-learning suitability modeling (XGBoost with SHAP), deep-learning land-use simulation, and monetary ecosystem-service valuation to compare three scenarios for 2030 and 2050: business-as-usual, suitability-based autonomous transformation, and a suitability-based landscape-approach transformation. Suitability-guided scenarios outperformed business-as-usual, with the landscape-approach scenario producing the most stable multi-decadal outcomes for regulating and cultural services, but provisioning services could plateau or decline when ecological protection constraints limited intensive production.

Janine Opitz, Monika Egerer · Renewable Agriculture and Food Systems · Germany

An online survey of 111 responding projects from Germany's urban community gardening network examined the presence and diversity of nut tree species and the motivations and challenges for adopting and expanding them. Nut trees existed in almost half of the responding projects, but in small numbers with low yields, hindered by limited space, local laws and regulations, and interaction with other garden species, and only 50% of projects planned to incorporate more nut tree species in the future.

Finn Williams, Ruby Johnston, Aiden Campbell · International Journal of Horticulture and Food Science · Germany

At the Christchurch College of Food Technology in New Zealand, researchers compared five growing systems -- rooftop container, raised bed, peri-urban orchard, rural orchard (reference), and heated greenhouse -- for avocado (Persea americana) cv. 'Hass' under simulated Bavarian Plateau conditions, using a randomized complete block design with four replications over three years (2020-2022). The rural orchard yielded highest at 22.3 kg per tree, peri-urban raised beds achieved 18.7 kg per tree using 56% less land, and rooftop containers (200 L pots) produced only 6.8 kg per tree, confirming that container culture is viable but yield-limited; rooftop systems had the lowest weed pressure, peri-urban orchards supported the richest arthropod biodiversity, and ISSR molecular markers confirmed genetic uniformity among grafted plants across systems, ruling out somaclonal variation as a source of the yield differences.

Emmanouel Arizanis, Dimitrios Kyriazis, Vassilis Barkoukis · Journal of Adventure Education & Outdoor Learning · Europe

This study tested the effectiveness of a specially designed school garden project aimed at improving intrinsic motivation (enjoyment, satisfaction/effort), social skills (responsibility, cooperation), and behavior (attitude, intention) as components of environmental behavior, among 152 fourth- and sixth-grade primary school pupils in Greece (M = 10.89 years, SD = 0.99), assigned to intervention and control groups. Pupils were tested before the intervention, at its end, and two months afterward. Over an eight-week intervention of two hours per week aligned with the Greek school curriculum, the intervention group attended the school garden project while the control group attended unrelated projects. The analysis found the program had a long-lasting effect on pupils' environmental behavior.

Monika Onyszkiewicz, Marta Sylla · Sustainability · Poland

This study surveys the current state of active Community-Supported Agriculture (CSA) groups in Poland, identifying active CSA farms and analyzing their offers, reach, and member characteristics, motivation, and involvement. As of when the study was conducted in 2023/2024, 13 food-producing farmers were inventoried across 35 groups, reaching an estimated 1,200 people. Drawing on the experience of CSA communities elsewhere in Europe, the study concludes that an umbrella organization is needed to network Poland's CSA community and support active farmers through advocacy, education, and coordination of CSA development at the national level.

Małgorzata SIEMIONEK-RUSKAŃ, Małgorzata Siemionek · Journal of Environmental Management and Tourism · Europe

This study examines the integration of environmental priorities into participatory budgeting (PB) processes in selected European cities in Poland, Spain, and Portugal, using a qualitative case-study approach supported by literature review and document analysis. Case studies from Warsaw and Gdańsk (Poland), Barcelona and Valencia (Spain), and Lisbon and Porto (Portugal) were analyzed, drawing on academic sources, municipal budget reports, and environmental planning documents to examine how PB in each city has funded projects addressing green infrastructure, waste management, energy efficiency, sustainable transport, and climate adaptation. The study finds that participatory budgeting in these cities has funded projects including community gardens, green roofs, riverbank restoration, and bicycle infrastructure.

Christos Ioannides, Alexandra Tsatsou, Daniel Mamais, Simos Malamis, Georgios Tsimiklis, Dimitra Tsiakou, Z. Tsiropoulos, Mariarina Michailidou, Apostolos Tzourtziotis, Christina Karaberi, Orestis Raptis, Constantinos Noutsopoulos · Urban Water Journal · Europe

This study presents the design, implementation, and evaluation of a city-wide pilot of circular urban agriculture across 31 locations in Trikala, Greece. The pilots included rainwater harvesting, precision irrigation, composting, and an online monitoring platform. Assessed through a mixed-methods approach using 20 environmental, economic, and social indicators, the system showed stable technical performance and effectiveness in reducing resource consumption.

Pengxuan Xie, José M. Mogollón, Jan Willem Erisman, Valerio Barbarossa · Sustainable Cities and Society · Europe

This study models spatial and temporal crop rotations on Amsterdam's rooftops using planting-structure optimization for crop rotation planning, to assess how much of the city's dietary demand for specific crop groups could be met by productive green roofs. Using average productive green roof crop yields and climatic variability from 2003-2021, it estimates Amsterdam's potential productive green roofs could achieve urban food self-sufficiency of 52% for selected crops (41-54% accounting for climatic and spatial variability), rising to 71% (50-71%) when the planting structure is optimized. Lettuce-broccoli occupies the largest productive green roof area, at roughly 100 hectares, and six vegetable types were found to match well with Amsterdam's dietary requirements.

Jarosław Chmielewski, Barbara Gworek, Alicja Walosik, Magdalena Florek-Łuszczki · Annals of Agricultural and Environmental Medicine · Poland

Soil (N=196) and root vegetable (N=94) samples from 16 allotment gardens in Warsaw, Poland, were analyzed for manganese, zinc, copper, lead and cadmium and assessed for health risk. Parsley, carrots, beetroots and celery grown in these gardens accumulated elevated levels of all five metals, and the health risk assessment found an increased risk of carcinogenic effects from cadmium and lead in consumers of these root vegetables; the authors conclude consumption of vegetables from the examined gardens should be very limited or eliminated from the diet entirely.

Anna Stage (17743305), Marie Caroline Vermund (11075551), Mads Bølling (6661577), Camilla Roed Otte (21175813), Alberte Laura Oest Müllertz (21175816), Peter Bentsen (3527732), Glen Nielsen (10468844), Peter Elsborg (8894495) · Figshare · Europe

This is the SPIRIT checklist for the FoodACT protocol, a multimethod, quasi-experimental study preregistered with ClinicalTrials.gov (#NCT05839080) investigating how the existing Danish school garden program Gardens to Bellies (GtB), delivered at six locations across Region Zealand and Region of Southern Denmark, affects fourth-grade pupils' food literacy, climate change literacy, school motivation and physical activity. Approximately 1,600 pupils attending GtB form the intervention group and approximately 1,600 pupils from non-participating schools form the control group, with pupils in the eight-session program growing, preparing and cooking foods; outcomes will be measured via pre/post surveys, accelerometry in a 900-pupil subsample, text-message surveys and semi-structured and focus-group interviews, analyzed using linear mixed models and thematic analysis. As a protocol document, it describes study design rather than results.

Ylva Wallinder · Local Environment · Europe

A study of Gothenburg, Sweden, examines the city council's shift over the past decade from associational (collective) urban gardening toward entrepreneurial gardening on municipal land, promoted through a scheme called "from garden box to hectare" that draws residents into entrepreneurial training while taking municipal gardening classes. Analyzing the consequences of this commodification of urban sustainability projects, the study finds that socio-economic resources and social relations both limit and strengthen entrepreneurial gardening practices and participants' quality of life, and that perceived competition among gardeners has turned urban gardening into a lonely, precarious, and individualized activity compared with the formalized associational gardening the municipality previously promoted. The finding points to a mismatch between the local government's sustainability visions and gardeners' actual experience.

Ouiam Fatiha Boukharta, Loïc Sauvée, Fabiana Pena-Fabri, Leticia Chico-Santamarta, Luis Manuel Navas-Gracia · Cities · France

In Rouen, France, a two-level urban agriculture governance system—the metropolitan authority and the City of Rouen—was examined through 19 semi-structured interviews with project stakeholders. The two levels shared similar approaches to social aspects, education, fresh produce consumption, and the goal of long-term project viability, but differed in project selection criteria: the metropolis applied less strict requirements than the city regarding plot size and soil analysis.

Diego López-Collar, Pietro Agostini, Francisco J Cabrero-Sañudo · DIGITAL.CSIC (Spanish National Research Council (CSIC)) · Europe

This study reports the first records of two non-native ant species, Monomorium carbonarium (1858) and Cardiocondyla mauritanica (1890), within the urban area of Madrid, Spain, along with updated occurrence records for the Argentine ant (Linepithema humile). These detections are mostly associated with irrigated green spaces—public parks, private gardens, urban orchards, and landscaped medians—and confirm that Mo. carbonarium and C. mauritanica are established in the city, extending their known Iberian distributions beyond coastal areas into the interior, while new Li. humile records point to its persistent, patchy distribution across Madrid.

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.

ADEME · ADEME Infos · France

One year after France's January 2024 mandate for source-separated food waste, ADEME reports that about 50% of residents (32.1 million people) now have access to municipal sorting services, 56% sort their food waste, and 9 million tonnes of biowaste per year have been diverted from incineration and landfill, backed by €100 million in green-fund investment since 2023.

Anne Lenormand · Banque des Territoires (Localtis) · France

Reporting that France's source-separation infrastructure for biowaste has tripled in three years since the January 2024 legal mandate, giving 32.1 million French residents (about 50%) access to sorting solutions (municipal collection, individual and shared composting). The rollout had a difficult start but is now accelerating, with 20 million more residents expected to gain access.

Department for Environment, Food & Rural Affairs, HM Treasury, Department for Business and Trade · GOV.UK · United Kingdom

On 23 December 2025 the UK government announced it would raise the 100% Agricultural and Business Property Reliefs threshold from £1m to £2.5m, effective 6 April 2026. Married couples or civil partners will be able to pass on assets worth up to £5m tax free, and up to £5.65m when combined with existing nil-rate bands. The government projects that the number of estates claiming agricultural property relief affected by the 2026-27 reforms will roughly halve, from 375 to 185.

Ministry of Housing, Communities & Local Government (MHCLG) · Ministry of Housing, Communities & Local Government (MHCLG) · United Kingdom

According to MHCLG's statistical release (published 9 October 2025), the extent of land designated as Green Belt in England as at 31 March 2025 was estimated at 1,633,220 hectares, around 12.5% of England's land area. This represents a decrease of 660 hectares (0.04%) from 31 March 2024, driven mainly by local authority boundary policy changes (650 hectares across six authorities) and digital boundary updates (10 hectares). By region, London has the highest proportion of its area designated Green Belt, at 22.1%.

Ministry of Housing, Communities & Local Government (MHCLG) · Ministry of Housing, Communities & Local Government (MHCLG) · United Kingdom

A technical note describing how the UK's MHCLG compiles official statistics on green belt land in England, collecting area figures as of 31 March each year from local authorities via the Annual Green Belt (AGB) return. The 2024-25 response rate was 99% across 177 local authorities, and prior-year area figures are subject to scheduled revisions.

European Environment Agency (EEA) · European Environment Agency (EEA) · Europe

According to this EEA indicator, water scarcity affected 28% of EU territory during at least one season in 2023. Although water abstraction fell 14% across the EU between 2000 and 2023, the area affected by water scarcity has not shrunk overall. Southern Europe experiences water scarcity year-round, with about 30% of the population in areas of permanent water stress and up to 70% in areas of seasonal summer stress; Cyprus and Malta are the most severely affected (seasonal WEI+ above 40%), with Greece, Romania, Portugal, Italy and Spain also notably affected in spring and summer.

· Wikipedia (español) · Spain

According to Spanish Wikipedia, the exact founding date of the Water Tribunal is unknown, though the most widely held theory dates it to around 960 CE, during the reign of a Caliph. It is made up of eight síndicos, one representing each irrigation community, one of whom generally serves a two-year term as president. It meets every Thursday at noon (except from Christmas to 6 January and on public holidays) at the 'Door of the Apostles' of Valencia Cathedral, with administrative meetings afterward at the Casa Vestuario on Plaza de la Virgen. It was inscribed by UNESCO as intangible cultural heritage on 30 September 2009.

· Viquipèdia (català) · Spain

According to Catalan Wikipedia, the irrigated farmland (horta) of Valencia took shape in the Middle Ages under Islamic rule through the construction of séquies (irrigation channels) and assuts (weirs). The main séquies of the Túria river have been governed since Islamic times by the Tribunal de les Aigües, inscribed by UNESCO as intangible cultural heritage in 2009. Eight séquies in the Vega de València draw water from the Túria and have historically supported orange, vegetable and rice cultivation, but many now run beneath houses and streets, with rice farming described as being in crisis as farmland is converted to housing.