Research & reports

Guido Evangelista, Juan David Arosemena, Gaia Stringari, Joan Romanyà, Xavier Gabarrell, Francesco Orsini, Gara Villalba · Agriculture Ecosystems & Environment · Global

This study evaluated the application of 150 t ha-1 of ramial chipped wood (RCW) to degraded peri-urban agricultural soils, comparing its effects on yield, soil health, and greenhouse gas emissions for spinach and sweet potato. Spinach grown with RCW showed the lowest productivity (1.16 – 0.32 kg m-2) among treatments, while sweet potato achieved the highest yield (1.72 – 1.99 kg m-2). High RCW doses initially led to higher CO2 emissions but significantly reduced N2O emissions for spinach (from 0.36 kg ha-1 to 0.07 kg ha-1) and enhanced soil organic carbon and nitrogen stocks for sweet potato, indicating agronomic and environmental trade-offs.

Xiaoya Lin, Jiajun Xu, Ting Wang, Randy A. Dahlgren, Lanyue Feng, Wenli Qin, Qinglong Liang, Zhixia Qin, Zengling Ma, Liyin Qu · Environmental Technology & Innovation · Global

A two-year monthly investigation of water quality and dissolved organic matter (DOM) optical properties (absorbance and fluorescence) in a eutrophic, urban-agricultural wetland. Dissolved organic carbon (DOC) increased from spring to summer in both years and correlated significantly with trophic level index (TLI), total nitrogen, COD, and chlorophyll a, indicating that eutrophication added to the organic carbon pool through both sewage inputs and algal production. Loss of protein-like component C3, together with a significant negative correlation between microbial humic-like component C2 and dissolved oxygen, suggested that microbial deoxygenation converted bio-labile DOM into recalcitrant DOM (RDOM) during summer. In winter, lower temperatures limited microbial transformation, and continuous sewage inputs increased protein-like C3, while RDOM removal via particle adsorption-sedimentation and photodegradation exceeded its accumulation. Machine learning analysis found microbial transformation explained 39.1-41.2% of variation in humic-like components, more than terrestrial inputs, sewage sources, and algal production combined (2.1-31.6%), identifying microbial transformation as the dominant driver of wetland RDOM formation. Eutrophication is stated to have negative effects on wetland ecosystems, though the study also notes that, if sewage and algae are effectively managed, the same process could enhance carbon sequestration.

Piaopiao Ke, Beñat Olascoaga, Pasi Kolari, Outi Tahvonen, Sami Haapanala, Tom Kokkonen, Leena Järvi, Markku Kulmala, Anna Lintunen · Urban forestry & urban greening · Finland

A year-round eddy covariance and soil chamber measurement in an urban allotment garden in southern Finland showed it functioned as a net CO₂ source (0.69 kg m⁻² yr⁻¹) despite 77% vegetation cover. High respiratory emissions (4.7 kg m⁻² yr⁻¹) exceeded photosynthetic uptake (4.0 kg m⁻² yr⁻¹), likely due to elevated soil organic carbon (13.4 ± 8.7%) and high soil C:N ratio from management amendments. These findings challenge assumptions about urban gardens as inherent carbon sinks and suggest carbon-smart management practices are needed.

Yanick Borel Kamga Valerie Njitat Tsama* · Journal of Biodiversity and Environmental Sciences (JBES) · Cameroon (Nkongsamba)

This study assessed the impact of untreated waste from the municipal slaughterhouse in Nkongsamba, Cameroon, on vegetation by conducting floristic inventories at upstream, near, and downstream sites. Twenty-five 100 m2 plots were established at each site, revealing a total of 105 species from 79 genera and 41 families. The downstream site exhibited the highest species richness with 81 species, 70 genera, and 35 families, but these results showed a dominance of ruderal taxa and pollution bio-indicators like Commelina benghalensis and Tithonia diversifolia, reflecting ecological disturbance of the plant environment.

Aashna Sinha, Kailash Bisht, Digvijay Singh · · Global

This article explores vertical hydroponic farming, noting its benefits like reduced space and water use, and enhanced robustness with Plant Growth-Promoting Microorganisms (PGPMs). However, it also demonstrated that the system's ecological impact is significantly affected by growing media, pots, electricity use, and transportation. The study suggests potential for reducing greenhouse gas emissions and abiotic resource decline by using fiber as growing medium and paper containers.

Diana Elinos, M. Carolina Cruz, Andrea Loyo del Castillo, Mar Zamora, Grecia Karime Yebra Peralta, José Gabriel Reyes Fernández · Memorias del Concurso Lasallista de Investigación Desarrollo e innovación · Global

This study analyzed the impact of inorganic pesticides, highlighting their potential mutagenic and carcinogenic effects and negative impact on biodiversity, water, and soil contamination. It proposed a methodology for creating an organic pesticide and presented results on its efficacy in pest control. The study concluded that inorganic pesticides pose significant risks, while organic pesticides offer a safe and effective alternative, and emphasized the need to prioritize organic solutions in agriculture.

María Virginia Maiza, Joan Muñoz‐Liesa, Anna Petit‐Boix, Verónica Arcas‐Pilz, Xavier Gabarrell · Resources Conservation and Recycling · Global

A life cycle assessment compared three human urine management strategies for nitrogen fertilizer production: an artificial wetland, an on-site lab-scale aerobic reactor (S2), and a centralized wastewater treatment plant. S2 showed the highest environmental impacts in 6 out of 8 categories, including high energy demand (750 kg MJ-eq) and ecotoxicity (602 kg 1.4-DCB-eq), although it offered an advantage in marine eutrophication. Upscaling S2 could reduce impacts and lower payback time, with nitrogen production exceeding 2.3 times the yearly demand for building tomato production.

Leigh Whittinghill, Major Ballard, Anju Chaudhary, Smriti Kandel, Caitlin Mullins, Pradip Poudel · HortScience · United States

This study analyzed runoff water quality from four different nutrient management treatments (conventional fertilizer, organic fertilizer, low-compost + organic fertilizer, and high compost) in raised beds and small plastic pool container plots in the United States. Water samples, collected monthly, were analyzed for pH, conductivity, color, turbidity, nitrate-nitrogen, ammonia-nitrogen, total phosphorus, and potassium. While significant differences existed between raised beds and container plots, these did not translate to meaningful water quality differences for most variables, except for nitrate-nitrogen. The conventional fertilizer treatment showed greater or more variable nutrient leaching than other treatments.

Iván Nocua, Karen del Pilar Galindez, J. Cordero, Astrid Del Pilar Ardila Bernal, Julián Serna, Omar David Guzmán, Cristian Fernando Camargo Muñoz, Mauricio Parra‐Quijano · Agronomía Colombiana · Colombia (Bogotá)

An urban garden was established within a greenhouse at the Universidad Nacional de Colombia, Bogotá campus, to investigate the effects of weeds and compacted soil in a biointensive approach. Over a two-month measurement period, 13 weed species were identified, with Veronica spp. being the most represented, and Poaceae family plants predominant within the orchard. While soil properties improved with the biointensive method and organic material addition, the presence of weeds highlights challenges and limitations in establishing urban gardens.

Angelica Mendoza Beltrán, Kelzy Jepsen, Martí Rufí-Salís, Sergi Ventura, Cristina Madrid‐López, Gara Villalba · The Science of The Total Environment · Spain (Barcelona)

This study mapped N2O emissions from peri-urban agriculture in the Metropolitan Area of Barcelona (AMB), Spain. Researchers spatially distributed factors like crop type, fertilizer use, and irrigation, creating N2O emission maps using crop-specific and Tier 1 IPCC emission factors (EFs). The study found that Tier 1 IPCC EFs estimated 15% more emissions (7718 kg N2O-N year−1) than crop-specific EFs (6533 kg N2O-N year−1) for the entire AMB, indicating higher emissions for rainfed crops with Tier 1 EFs and for irrigated horticultural crops with crop-specific EFs. The mapping helps evaluate spatial variability of key factors but carries uncertainties due to downscaling regional data.

Ionat; id_orcid 0000-0001-9080-2282 Zurr, Oron; id_orcid 0000-0002-2893-5364 Catts · UWA Profiles and Research Repository (University of Western Australia) · Australia

The "Sunlight, Soil & Shit (De)Cycle" project, presented by SymbioticA in February 2022, is a performative experiment exploring agricultural technology (AgTech) and its aim to remove natural elements like sunlight, soil, and organic waste from food production. This project considers whether the precursor to sustainable food systems will be the creation of a metabolic rift, where the means of production grow ever distant from nature. It highlights a critical environmental tradeoff by questioning the separation of humans from nature in technological farming.

Muhammad Sarjan, M. Taufik Fauzi, Ruth Stella P. Thei · Unram Journal of Community Service · Indonesia (Mataram City)

This action research in Mataram City during the COVID-19 pandemic introduced Integrated Pest Management (IPM) practices to urban farming groups. Group discussions revealed that while participants were interested in developing fresh vegetables and fruits and found benefits in meeting family food needs, most members were unfamiliar with environmentally friendly cultivation techniques, particularly IPM.

Monika Egerer, Brenda B. Lin · CABI Reviews · Global

This review evaluated ecosystem services (ES) within urban agriculture (UA) systems and the trade-offs between these services. Urban agriculture provides many benefits and environmental services such as food provision, social cohesion, and climate regulation. However, it was shown that management decisions can create trade-offs between ecosystem services, where an increase in one service may potentially reduce the system's ability to provide another service at a desired level.

Anne-Louise Fritz, Ramia Jannoura, René Beuschel, Christoph Steiner, Andreas Buerkert, Rainer Georg Joergensen · Chemical and Biological Technologies in Agriculture · Africa

This 2-year study in semi-arid Ouagadougou and sub-humid Tamale, West Africa, measured the effects of biochar and N fertilization on soil microbial biomass carbon, fungal ergosterol, and functional diversity. Sole biochar addition did not affect soil chemical or biological properties, but biochar with N fertilization increased microbial respiratory response. N fertilization decreased soil pH by 1.1 units in both cities, and a pH of 4.7 led to reduced microbial biomass carbon and ergosterol contents in Tamale. An N fertilizer-induced decline in soil pH below 5 should be avoided, as it decreased microbial biomass carbon and microbial functional diversity.

Paulien C. H. van de Vlasakker, Karin Tonderski, Geneviève S. Metson · Frontiers in Sustainable Food Systems · Global

A review of empirical peer-reviewed studies (2000-2021) on nutrient losses to water from soil- and ground-based urban agriculture. Of 241 publications screened for a stated concern with nutrient losses to water, 20 were retained, but only seven had actually measured losses to water. Of four experimental studies, three measured leachate losses under different garden management practices; of 16 real-world studies, only four quantified losses to water as leachate, with measured average losses ranging from 0.005 to 6.5 kg/ha for phosphorus and 0.05 to 140 kg/ha for nitrogen. Thirteen of the 16 non-experimental studies provided input and harvested-crop data allowing nutrient balances to be calculated; despite wide value ranges, most studied gardens showed nutrient surpluses (inputs exceeding crop harvest) for nitrogen and phosphorus but not potassium, identified as a risk factor for losses to water, though large surpluses were not always linked to higher leachate losses. The review concludes that more field studies measuring actual losses to water, and documenting contextual factors, are needed to determine whether urban agriculture can contribute to a circular economy without causing nutrient-related water quality impairment.

Solomon Tulu Tadesse, O. Oenema, Christy van Beek, Fikre Lemessa Ocho · Frontiers of Agricultural Science and Engineering · Ethiopia

This study in Jimma, Ethiopia, from 2015-2050, used an N mass flow model and field experiments to explore manure recycling from urban livestock farms under four scenarios. It found that livestock manures are the main organic wastes in urban areas, and manure production in urban and peri-urban agriculture (UPA) is projected to increase 3 to 10 times. Critically, only 13% to 38% of manure nitrogen will be recycled in croplands, and intensification of urban livestock production greatly increased nitrogen surpluses, indicating a significant environmental tradeoff.

Maha Deeb, Peter M. Groffman, Manuel Blouin, Sara Perl Egendorf, Alan Vergnes, Viacheslav Vasenev, Donna L. Cao, Daniel C. I. Walsh, Tatiana Morin, Geoffroy Séré · SOIL · Global

This review examines the use of Constructed Technosols (CTs), mixtures of organic and mineral waste, for green infrastructure (GI) in urban spaces. While CTs have high potential to provide multiple soil functions and contribute to urban greening, urban soils are often physically, chemically, or biologically unsuitable for GI features. The analysis suggests that the composition and structure of CTs should be adapted to available wastes and by-products, as well as future land use and environmental conditions, highlighting the need for careful design to overcome existing limitations.

Noiry Pérez Pompa, Santa Laura Leyva Rodríguez · Sinergia Académica · Cuba

A diagnosis of farms infested by Dichrostachys cinerea (marabú) in urban and suburban agriculture was conducted at Los Téllez farm in Becerra, Las Tunas municipality, Cuba. Soil quality indicators for reddish-brown Fersialitic soils over granitoids were evaluated across four land-use systems: two infested by D. cinerea and two agricultural systems cultivated for 10 years after marabú deforestation. Results showed that D. cinerea systems exhibited the highest soil quality index, based on organic matter, bulk density, and earthworm biomass. Conversely, cultivated systems achieved the lowest accumulation of organic carbon, oligochaete density and biomass, and total porosity.

Jennifer Engels, Sheree J. Watson, Henrietta Dulai, Kimberly Burnett, Christopher A. Wada, ‘Ano‘ilani Aga, Nathan DeMaagd, J. J. McHugh, Barbara Sumida, Leah L. Bremer · PLoS ONE · United States (O‘ahu)

A researcher-farmer collaboration on O‘ahu's Sumida watercress farm conducted a 25-year trend analysis and a year of intensive spring water sampling. Negative correlations were found between historical crop yields and increases in the Oceanic Niño Index, temperature thresholds, and pest outbreaks. Despite urbanization, on-farm water quality was very high, and microbial analyses suggested the farm provides nutrient retention services to downstream systems. The study demonstrates that challenges facing urban agricultural systems shift over time.

Delphine Manka’abusi, Désiré Jean‐Pascal Lompo, Christoph Steiner, Mariko Ingold, Edmund Kyei Akoto-Danso, Steffen Werner, Volker Häring, George Nyarko, Bernd Marschner, Andreas Buerkert · Journal of Plant Nutrition and Soil Science · Sub-Saharan Africa

To quantify carbon and nitrogen losses in urban and peri-urban agriculture soils in West Africa, this study measured CO2-C, N2O-N, and NH3-N fluxes from irrigated fields in Ouagadougou, Burkina Faso, and Tamale, Ghana, under different fertilization and (waste)water regimes. Compared with unamended controls, fertilizer application increased average cumulative CO2-C emissions by 103% over eight cropping cycles in Ouagadougou and by 42% over seven cropping cycles in Tamale. Total emissions across all cropping cycles reached 14 t C/ha in Ouagadougou — 73% of the carbon applied as organic fertilizer over two years at that site — and 9 t C/ha in Tamale. Fertilizer application increased N2O-N emissions in Ouagadougou by 37-360% across cropping cycles and NH3-N losses by an average of 670%, but had no significant effect on N2O-N losses in Tamale. Wastewater irrigation did not significantly raise CO2-C emissions in Ouagadougou, but in Tamale CO2-C emissions were 71% higher on wastewater plots (1.6 t C/ha) than on controls (0.9 t C/ha); wastewater had no significant effect on N2O-N or NH3-N emissions at either site. Biochar did not affect N2O-N or NH3-N losses but could help reduce CO2-C emissions from urban garden soils.

Simon Tresch, David Frey, Renée‐Claire Le Bayon, Paul Mäder, Bernhard Stehle, Andreas Fließbach, Marco Moretti · Scientific Reports · Switzerland (Zurich)

A study in 85 urban gardens across Zurich, Switzerland, investigated the impact of gardening on five soil functions and the relationship between plant (600 spp.) and soil fauna (18 earthworm spp., 39 springtail spp.). High plant diversity positively affected soil fauna and multifunctionality, but intense garden management decreased plant diversity. This indicates a trade-off where intensive gardening, while potentially beneficial for some aspects, can negatively impact overall plant diversity.

Gaston E. Small, Sara Osborne, Paliza Shrestha, Adam D. Kay · International Journal of Environmental Research and Public Health ·

This study measured phosphorus (P) concentrations in native soil below four- and six-year-old urban garden plots, collecting soil cores from five plots of each age. It found that inorganic weakly exchangeable P was significantly elevated in native soil below garden plots (>35 cm deep) compared to reference profiles, indicating accumulation of excess P from compost. This suggests that while urban agriculture can recycle P, over-application of compost may contribute to soil and water pollution.

Gaston E. Small, Paliza Shrestha, Geneviève S. Metson, Katherine Polsky, Ivan Jimenez, Adam D. Kay · Environmental Research Communications · United States

Survey data from 142 gardeners and urban farmers in the Twin Cities Metropolitan Area, USA, characterized phosphorus (P) and nitrogen (N) inputs and harvest, and measured soil P concentrations at a subset of sites. Median application rates were 300 kg P/ha and 1400 kg N/ha, with low nutrient use efficiencies (2.5% for P, 5.0% for N). Garden soils had a median Bray P value of 80 ppm, far exceeding recommended levels, indicating a buildup and potential loss of P and N. Urban gardens, though only 0.1% of land area, constitute one of the largest inputs of P to the watershed.

Odiney Alvarez‐Campos, Gregory K. Evanylo · Journal of Environmental Quality · Global

The impacts of exceptional quality (EQ) biosolids and inorganic fertilizer applied for rehabilitating anthropogenic soils on potential nitrogen (N) and phosphorus (P) water quality impairment risk were compared. After two years, reclamation rates of biosolids resulted in soil P saturation ratios greater than the recommended 30% but lower than the 65% limit. While nitrate N (NO3–N) posed the greatest nutrient leaching risk, lysimeter-collected mass loading of NO3–N from reclamation rates was not greater than for the inorganic fertilizer.

Delphine Bernadette Ouédraogo, Delwendé Innocent Kiba, Zacharia Gnankambary, Sheick K. Sangaré, Diakouba Sirima, Hassan Bismarck Nacro, Michel Papaoba Sédogo · Journal of Agricultural Science · Burkina Faso (Ouagadougou)

This study investigated cropping practices and their drivers in 133 peri-urban farms near Ouagadougou, Burkina Faso. Soil sample analysis revealed that monoculture led to low soil organic carbon, while polyculture led to low soil available potassium. The socio-economic conditions of the farms explained up to 60% of the variability in cropping practices.