Research & reports

MDRC · MDRC · United States

A project page for ABLE (Adolescent Behavioral Learning Experience) at New York City's Rikers Island, the first US social impact bond. Goldman Sachs invested $9.6 million over four years, backed by a $7.2 million guarantee from Bloomberg Philanthropies. The programme served 16- to 18-year-olds, a group with a recidivism rate near 50 per cent within a year and more than 200 additional days in jail over six years, against a New York City incarceration cost above $85,000 per person per year. Cognitive behavioural therapy was cited as capable of cutting recidivism by up to 25 per cent, and the payment threshold was set at a 10 per cent reduction; a pilot ran February–June 2012 and full implementation from September 2012 to August 2015, with Moral Reconation Therapy delivered by The Osborne Association and Friends of Island Academy.

· Wikipedia · Global

The GIIN is a New York nonprofit founded in September 2009 by Amit Bouri and Antony Bugg-Levine, publicly unveiled on 25 September 2009 by Bill Clinton at the Clinton Global Initiative. It exists to scale and professionalise impact investing, running conferences and market research and managing the IRIS impact-measurement standards (launched 2009, succeeded by IRIS+ in 2019) and the Operating Principles for Impact Management. It had 421 member organisations as of June 2025, revenue of $16,484,237 and total assets of $16,968,824 in 2022, and 186 companies across 40 countries had signed the Operating Principles as of March 2025.

Zhao H., Wardropper C.B., Cao H., Campbell C.G., Chang N.-B., Qiu J. · npj Urban Sustainability · United States (South Florida)

A University of Florida (UF/IFAS) study of where public support for urban agriculture actually comes from, combining a survey of 1,000 adults across Miami-Dade, Broward and Palm Beach counties (in English and Spanish) with AI-assisted analysis of thousands of US news stories over the past decade. Support is not monolithic: different behaviours have different drivers. A sense of community connection predicts financial donations; hands-on gardening experience predicts volunteering; a sense of shared responsibility predicts buying local produce and backing policy. News interest has risen especially since COVID-19, and is strongest in Florida and West Coast states. The authors conclude that outreach tailored to the specific behaviour being sought works better than one uniform message.

Kremer, Peleg, Borowiak, Craig, Scolio, Madeline · Journal of Agriculture, Food Systems, and Community Development · 米国（ペンシルベニア州フィラデルフィア）

US community gardens embody a conundrum: vital to community well-being and integral to urban social infrastructure, yet profoundly vulnerable through insecure land tenure, fragmented policy support and systemic disinvestment. This reflective essay examines the Philadelphia Garden Data Collaborative (PGDC), a multistakeholder initiative documenting, protecting and advocating for community-managed green space, from the authors' position as participant researchers. It traces the shift from grassroots mapping to coordinated data stewardship, which enabled both emergency interventions (such as preventing sheriff-sale evictions) and long-term preservation strategies, and examines the ethical dilemmas of collecting sensitive community data where bureaucratic neglect has rendered gardens invisible and where visibility can expose them to new risks. It concludes that data can strengthen advocacy and inform policy, but must be coupled with secure tenure mechanisms and sustained public investment.

Pearson, Natalie · British Food Journal · 英国（食を育てる人びとへの質的調査）

It is often argued that growing one's own food reduces household food waste by raising appreciation of food, but focused research on this is lacking. Using thematically analysed qualitative surveys with a privileged sample of food gardeners, this study finds the relationship more complex than proposed: for these gardeners, growing their own food can also decrease appreciation of food and create waste because of the challenges of growing, processing and storing it. Food gardening could nonetheless become an instrumental waste-prevention practice if growing is made easy and convenient, gardeners are given opportunities to work together, more channels exist for sharing surplus, and cooking skills improve. Its contribution is to critique the assumption that growing your own always leads to appreciation of food and less waste.

Gao, Si, Burce, Katrina, Smith, Laney, Espinoza, Nina, Melbourne, Alfred · Frontiers in Soil Science · 米国（カリフォルニア州ウェスト・サクラメント）

Urban agriculture soils are commonly amended with compost, yet how such systems respond functionally to biochar across application rates is poorly understood. In a field experiment at Three Sisters Gardens (West Sacramento, CA, USA), biochar was applied at 0, 10, 20 and 30 t/ha to compost-amended plots under corn and squash, and late-season soils were analysed for physical, chemical and biological indicators. Intermediate rates (10–20 t/ha) improved aggregate stability and increased soil respiration; the highest rate (30 t/ha) produced the strongest biological responses, including higher microbial biomass, fungal:bacterial ratios and extracellular enzyme activities in nitrogen and phosphorus cycling. Soil pH and cation exchange capacity did not differ significantly among treatments. Regression analyses indicated nutrient availability was more strongly associated with microbial indicators than with bulk soil chemistry, consistent with microbial mediation of biochar-associated nutrient dynamics, and the patterns held broadly across both cropping systems.

Bundesverband der Kleingartenvereine Deutschlands (BKD) · Bundesverband der Kleingartenvereine Deutschlands (BKD) · Germany

The national statistics page of the German federation of allotment garden associations (BKD). It gives the base figures — 867,092 plots, 44,000 hectares, an average plot of 370 square metres — along with the three-tier structure of roughly 13,000 clubs, 502 district federations and 20 state federations, membership by state, and a ranking of plots in the 15 largest cities (Berlin about 66,000, Leipzig 39,000). The nationwide average wait for a plot is three years, rising to seven in Berlin and eight in Hamburg. It also shows the skew by which the eastern states excluding Berlin, holding 15 per cent of the population, contain more than half of all allotments.

Gesellschaft für Schleswig-Holsteinische Geschichte · Gesellschaft für Schleswig-Holsteinische Geschichte · Germany

An encyclopaedia entry from the Society for Schleswig-Holstein History. It dates the appearance of 'poor gardens' in the duchies to the end of the 1820s and records that by 1826 they existed in 19 towns. In 1830 the Society of Voluntary Friends of the Poor in Kiel allocated plots on the municipal land at the Prüner Schlag at a size of 400 square metres — a size the entry says still holds today. The initiative is attributed to the governor Landgrave Carl of Hesse (1744–1836); the entry notes that the later allotment movement begun by the Leipzig physician D. M. Schreber (1808–1861) turned the poor gardens into Schrebergärten.

VGT Gartenfreunde Treptow e. V. · VGT Gartenfreunde Treptow e. V. · Germany

A source page in which the Berlin-Treptow garden association explains the Allotment and Small-Lease Ordinance of 31 July 1919 clause by clause. Section 1 put the rent for non-commercial horticultural land in the hands of the lower administrative authority, to be set in light of local conditions and land values after consulting agricultural and horticultural experts. Section 3 barred the landlord from terminating the lease, gave the holder a right to convert a loan for use into a lease, and a right to demand renewal once a term expired. Under section 4 an allotment office was set up in the Treptow district administration, which lasted until 1938. The association's 1948 statutes, the page notes, still referred back to the 1919 ordinance.

· Wikipedia (Deutsch) · Germany

The article on the history and scale of Germany's national allotment federation. Founded on 21 August 1921 as the Reich federation of German allotment associations, it later became the Bundesverband Deutscher Gartenfreunde and took its present name on 9 September 2023. It now covers more than 13,000 clubs and 20 state bodies, some 900,000 plots on 44,000 hectares used by around five million people — an area equal to 0.25 per cent of Germany's agricultural land. The article also carries the historical figures for 1938: one million members on 45,000 hectares, producing 350 million kg of fruit and 300 million kg of vegetables.

· Wikipedia (Deutsch) · Germany

The article on the VKSK, East Germany's national allotment organisation. Founded in Leipzig on 29 November 1959, it held the exclusive right to establish allotment sites. Membership stood at about 850,000 in 1962 and reached roughly 1.5 million by 1988. An extraordinary congress on 27 October 1990 resolved to dissolve the body with effect from 31 December 1990, and its gardeners and clubs passed into the all-German federation that followed.

· Wikipedia (Deutsch) · Germany

The article on Germany's intercultural gardens. The pilot project grew out of the initiative of immigrant families in Göttingen-Geismar in 1996, and as of 2025 more than 400 intercultural garden projects exist across the country. Support centres on the Stiftung Interkultur in Munich, described as a creation of the foundation partnership anstiftung & ertomis. The association at the movement's origin, Internationale Gärten e. V. Göttingen, was set up in 1998 and runs three gardens covering 11,000 square metres with around 70 families from 25 countries.

Landesverband Berlin der Gartenfreunde e. V. · Landesverband Berlin der Gartenfreunde e. V. · Germany

The Berlin state federation of garden friends tracing its own history. It counts roughly 40,000 'Pflanzer' in Berlin between 1890 and 1910 and places the origin of today's federation in the April 1901 union of all planter associations of Berlin and its surroundings. After a series of First World War emergency decrees capped rent increases and obliged municipalities to provide land for cultivation, the Allotment and Small-Lease Ordinance of 31 July 1919 imposed rent control, banned leasing for profit and allowed land to be secured compulsorily. On 20 October 1919 the board of Berlin's colonists voted to rename their body the central federation of German allotment associations; by 1929 the Berlin provincial federation had 66,570 members, and that year Rehberge in Wedding opened as what the page calls Germany's first permanent allotment colony.

Singh C., Koduganti M., Patil S. · Urban Studies · India

A study measuring the self-reported wellbeing outcomes of urban agriculture in India at individual and community level, drawing on a household survey (n=361), key informant interviews (n=50) and in-depth interviews with home gardeners (n=7). Its novelty is a dataset covering both formal and informal settlements, going beyond existing Indian data. Wellbeing is operationalised through physical and mental health, intra-family, community and beyond-human connectedness, and contribution to pro-environmental values. The authors find significant perceived benefits at individual, household and community levels, and that urban agriculture lets citizens participate, innovate and collectivise in deeply meaningful ways — concluding that it needs to be recognised and mainstreamed within ongoing urban sustainability and climate initiatives.

Teerlinck J., Dewaelheyns V., Wittemans K., Tzoulas K., Raymaekers P., Cavan G., Steen T., Somers B. · Urban Forestry & Urban Greening · Belgium (Flanders)

A paper on domestic gardens in Flanders, Belgium, examining how gardens are used, what they are composed of, and what stands in the way of climate change adaptation in them — treating the privately-held share of urban green space as an adaptation resource. Note: this entry is written from the paper's bibliographic record and title; see the article itself for its figures and conclusions.

Karasungur S., Yavaş M. · Land Use Policy · Türkiye (Erzurum)

A paper that frames urban agriculture as a land-use policy instrument for protecting peri-urban agricultural land from urbanisation, analysed on a grid basis for Erzurum, Türkiye. Its angle is to treat urban agriculture not only as growing food in the city but as an institutional means of restraining farmland conversion. Note: this entry is written from the paper's bibliographic record and title; see the article itself for its figures and conclusions.

Bundesverband der Kleingartenvereine Deutschlands (BKD) · Bundesverband der Kleingartenvereine Deutschlands (BKD) · Germany

The national allotment federation's own history page. It sorts the nineteenth-century origins into six lines — poor gardens, factory gardens, Red Cross workers' gardens, the Berlin arbour colonists, gardens of the natural-healing movement and the Schreber gardens — and states that these lacked state legitimation and legal rules, with the absence of termination protection and the head-tenant system (Generalpächtersystem) in particular obstructing lasting protection. It records the passage of the Kleingarten- und Kleinpachtlandordnung by the National Assembly in Weimar on 31 July 1919, which banned commercial head-leasing and required rents to be fixed; the 1909 founding of the central federation; the Reich government's 1916 establishment of a central office for vegetable growing in allotments; the founding of the Reich federation of German allotment associations on 14 August 1921 at the second Reich allotment congress in Bremen; the Nazi-era Gleichschaltung; the post-war split into the VDK (Bochum, 1949) in the West and the VKSK (Leipzig, 1959) in the East; the 1973 renaming to BDG; and the renaming to BKD on 9 September 2023.

Bezirksamt Pankow von Berlin · Bezirksamt Pankow von Berlin (berlin.de) · Germany

An exhibition text in which Berlin's Pankow district office traces the history of allotment sites in the district. It describes the spread of Red Cross workers' gardens in the early twentieth century and their consolidation in 1906 into the Verband deutscher Arbeitergärten vom Roten Kreuz under Alwin Bielefeldt (1857–1942); the head-tenant (Generalpächter) system common around the turn of the century, in which land was leased and sublet with contracts often running for a single year; and the Kleingarten- und Kleinpachtlandordnung of 31 July 1919, which gave legal protection and prohibited head-leasing. On the arbour colonists it records the first permanent municipal lease in Blankenburg on former sewage fields in 1910 and the 1911 formation of a unified federation of arbour colonists of Berlin and surroundings, and cites a 1912 survey finding that 70 per cent of Berlin schoolchildren had never seen a sunrise and 54 per cent no sunset. For the GDR period it notes the founding of the VKSK in 1959, more than a million members by 1988 and its dissolution on 27 October 1990; more recently, that of Berlin's 900 allotment sites roughly 600 were given permanent protection and about 160 only time-limited protection.

· Wikipedia (English) · Germany

The article on the German food crisis of 1916–17 during the First World War. It states that the Allied blockade reduced food supplies by 33 per cent and that the civilian diet fell to 1,560 calories a day by the summer of 1917 and to 1,000 calories a day in winter, against the 3,000 calories said to be needed by a healthy adult male. The name comes from the substitution of fodder swedes (turnips) for the failed potato crop. Female mortality is given as rising 11.5 per cent in 1916 and 30 per cent in 1917 against pre-war rates, and the historian G. J. Meyer is cited, quoting a Berlin physician, for the claim that eighty thousand children died of starvation in 1916. The historian Avner Offer is cited for the estimate that one-fifth to one-third of food could be obtained only through illegal channels.

Deutsche UNESCO-Kommission · Deutsche UNESCO-Kommission · Germany

The German UNESCO Commission's page on the Berlin Modernism Housing Estates, inscribed as World Heritage in 2008. It lists the component estates: Gartenstadt Falkenberg (built 1913–1916), Siedlung Schillerpark (1924–1930), the Großsiedlung Britz or Horseshoe Estate (1925–1930), Waldsiedlung Zehlendorf (1926–1932), Wohnstadt Carl Legien (1928–1930), Weiße Stadt (1929–1931) and Großsiedlung Siemensstadt (1929–1934). Alongside the 2008 inscription it records that the Waldsiedlung Zehlendorf was added in July 2026; that estate has more than 1,900 dwelling units on 70 hectares. The architects named are Bruno Taut, Martin Wagner, Walter Gropius, Hans Scharoun, Hugo Häring and Otto Rudolf Salvisberg.

Landesdenkmalamt Berlin · Landesdenkmalamt Berlin (berlin.de) · Germany

A short notice issued by the Berlin State Heritage Office on 27 July 2026. It reports that on 26 July 2026 the 48th session of the UNESCO World Heritage Committee, meeting in Busan, South Korea, inscribed the Waldsiedlung Zehlendorf as the seventh component of the World Heritage site 'Berlin Modernism Housing Estates'. The estate was built between 1926 and 1932 by the housing cooperative GEHAG and comprises 1,917 dwellings — 1,108 in multi-storey blocks and 809 single-family houses. The architects were Bruno Taut, Hugo Häring and Otto Rudolph Salvisberg, with the open spaces designed by Leberecht Migge and Martha Willings-Göhre. It lies around the U-Bahn station Onkel Toms Hütte on line U3 and along Argentinische Allee in the Steglitz-Zehlendorf district. The nomination process began in 2021.

Berliner Forum für Geschichte und Gegenwart e.V. · Welterbe Siedlungen der Berliner Moderne (Berliner Forum für Geschichte und Gegenwart e.V.) · Germany

The page on the Britz Horseshoe Estate from the official site for the Berlin Modernism Housing Estates World Heritage property. Construction ran from 1925 to 1931, with Bruno Taut and Martin Wagner responsible for the overall plan and urban design and Leberecht Migge and Ottokar Wagler for the garden design. The estate comprises 1,963 dwellings — 679 single-family rowhouses and 1,284 flats — ranging from 1.5 to 5 rooms. The World Heritage property covers 37.1 hectares with a 73.1-hectare buffer zone, and the emblematic horseshoe-shaped main block is 350 metres long. It was inscribed as World Heritage in 2008 and designated a garden monument in 2010.

Chifunda Emmanuel Felix, Kifunda Christina Felix · Cogent Food & Agriculture · タンザニア

A paper on urban and peri-urban agriculture in Dar es Salaam examined through the gender dynamics of the people working in it. The bibliographic record (authors, journal, DOI) was verified at the source, but the abstract could not be retrieved, so only the scope of the topic is described here.

Rduch Paulina, Hodor Katarzyna, Wilkosz-Mamcarczyk Magdalena · Cities · ポーランド・チェコ

A study of Katowice (Poland) and Brno (Czech Republic) examining how family allotment gardens function as greenery in city centres, together with the legal regulations that govern them. Drawing on statistical and cartographic data, it shows a downward trend in the area of allotment gardens within cities.

Bhaskaran Varsha, Nilon Charles H. · Urban Forestry & Urban Greening · インド

A paper framing home gardens in Bengaluru as everyday environmental stewardship by residents. The bibliographic record was verified at the source, but the abstract could not be retrieved, so only the scope of the topic is described here. The same authors have published related work on home gardens and urban wildlife in the city.