Would a sustainable city be self-sufficient in food production?

Small, Gaston E.; McDougall, Robert; Metson, Geneviève S.

doi:10.2495/dne-v14-n3-178-194

Cited by 7 publications

(5 citation statements)

References 59 publications

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“…Research question three required a more qualitative review of the retained studies. Previous framework papers on urban nutrient flows and resource use in UA highlight the need to consider the unique constellation of social, economic, technological, and ecological factors to identify drivers of observed patterns and intervention points (Metson et al, 2015a,b;Small et al, 2019a). These papers provided broad categories of contextual factors to consider.…”

Section: Discussionmentioning

confidence: 99%

“…There is a high potential for nutrient reuse in UA, but this can only be achieved sustainably if nutrients are used efficiently. UA can involve the inefficient use of resources in a particular city (Goldstein et al, 2016;Small et al, 2019a), which can in turn contribute to excessive resource extraction and pollution. Nutrient losses caused by ineffective N and P management in rural agriculture have been identified as main contributors to water quality impairment (Schröder et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

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A Review of Nutrient Losses to Waters From Soil- and Ground-Based Urban Agriculture—More Nutrient Balances Than Measurements

Vlasakker

Tonderski

Metson

2022

Front. Sustain. Food Syst.

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Urban agriculture has a high potential to contribute to local circular economies, for instance by using nitrogen, phosphorus, and potassium in city organic waste streams as fertilizer inputs. However, inefficient use of waste-derived fertilizers could contribute to local water quality impairment related to nitrogen and phosphorus losses. Organic waste derived fertilizers are particularly challenging from a nutrient stoichiometry perspective, making over- and under-application of a particular nutrient likely. Where, and under what conditions, urban agriculture acts as a net positive for a circular nutrient economy vs. a nutrient water quality risk remains unclear. Here we review empirical peer-reviewed studies (2000–2021) on soil- and ground-based urban agriculture with a stated concern for nutrient losses to water. Of the 20 publications retained and reviewed (out of 241 screened), only seven measured losses to waters. There were four experimental studies, of which three measured nutrient leachate losses under different garden management practices. Of the 16 studies done in real-world conditions, only four quantified losses to water as leachate; average losses spanned 0.005 to 6.5 kg ha−1 for phosphorus, and 0.05 to 140 kg ha−1 for nitrogen. 13 of the 16 non-experimental studies provided data on nutrient inputs and harvested crop outputs, which could be used to calculate garden nutrient balances—an indicator of nutrient use efficiency. Although the value ranges were large, most studied gardens showed nutrient surpluses (inputs > crop harvest) for nitrogen and phosphorus (but not potassium); these surpluses were identified as a risk for losses to water. Contextual factors such as different access to fertilizers and knowledge, along with regulations and environmental factors can help explain the wide range of balance values and nutrient losses observed. Although a large surplus of inputs was often linked to increased leachate losses, it was not always the case in the limited number of studies we identified. Our review suggests that more field studies that measure losses to waters, and document contextual factors, are needed to determine how urban agriculture may contribute to a sustainable circular economy for all three nutrients without nutrient-related water quality impairment.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Review of Nutrient Losses to Waters From Soil- and Ground-Based Urban Agriculture—More Nutrient Balances Than Measurements

Vlasakker

Tonderski

Metson

2022

Front. Sustain. Food Syst.

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“…It is compatible with green energy harvesting from organic waste and can also give other benefits to the circular economy (as indicated in Fig. 2), including job opportunities [25]. Since India is an agrarian nation, UA had long been a household tradition that began with the management of kitchen food waste, but it slowly got lost in the current patterns of urbanization.…”

Section: Literature Studymentioning

confidence: 99%

Urban Agriculture as a Sustainable Option for Solid Waste Management: Case Study of an Indian City

Agarwal

Bardhan

Das

2021

WIT Transactions on Ecology and the Environment

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The rapid growth of India's urban population coupled with food security concerns has driven urban agriculture into Indian cities. It is also commonly known that urban local bodies are struggling with the ever-increasing municipal solid waste, and in managing its segregation, transportation, and treatment. Inadequate organic waste management causes a slew of issues like gas emissions and health risks to the community. Since household wet wastes are full of nutrient-rich organic matter favorable for growing plants, urban agriculture provides an excellent opportunity of bridging the gap by reimagining waste as a resource. This study is based on the premise that decentralized urban waste management can be achieved through reusing and recycling organic waste that can benefit urban food production. It has conducted a qualitative and quantitative assessment of the organic waste usage in urban agriculture in the Indian city of Mumbai, Maharashtra. This paper presents the results of the study and examines the existing and potential capacity of urban agriculture in consuming organic urban waste in Mumbai's context. This case study also helps in visualizing circular economy against a real-life urban scenario and how the production-consumption loop may gainfully sustain each other. Based on the learning, the paper recommends mainstreaming urban agriculture into the sustainable city framework.

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“…Controlled environment systems are considered by some as key part of future food production ( Lakhiar et al, 2018 ; Cowan et al, 2022 ). This is largely due to the possibility of operating hydroponic systems in greenhouses in regions with unfavorable climatic conditions and in urban areas ( Sharma et al, 2018 ; Small et al, 2019 ). Closed hydroponic systems also allow the re-utilization of drained nutrient solution from the root zone by recirculating the collected drain after mixing with stock solution.…”

Section: Introductionmentioning

confidence: 99%

Sources of nitrous oxide emissions from hydroponic tomato cultivation: Evidence from stable isotope analyses

Karlowsky

Buchen‐Tschiskale²,

Odasso³

et al. 2023

Front. Microbiol.

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IntroductionHydroponic vegetable cultivation is characterized by high intensity and frequent nitrogen fertilizer application, which is related to greenhouse gas emissions, especially in the form of nitrous oxide (N2O). So far, there is little knowledge about the sources of N2O emissions from hydroponic systems, with the few studies indicating that denitrification could play a major role.MethodsHere, we use evidence from an experiment with tomato plants (Solanum lycopersicum) grown in a hydroponic greenhouse setup to further shed light into the process of N2O production based on the N2O isotopocule method and the 15N tracing approach. Gas samples from the headspace of rock wool substrate were collected prior to and after 15N labeling at two occasions using the closed chamber method and analyzed by gas chromatography and stable isotope ratio mass spectrometry.ResultsThe isotopocule analyses revealed that either heterotrophic bacterial denitrification (bD) or nitrifier denitrification (nD) was the major source of N2O emissions, when a typical nutrient solution with a low ammonium concentration (1–6 mg L−1) was applied. Furthermore, the isotopic shift in 15N site preference and in δ18O values indicated that approximately 80–90% of the N2O produced were already reduced to N2 by denitrifiers inside the rock wool substrate. Despite higher concentrations of ammonium present during the 15N labeling (30–60 mg L−1), results from the 15N tracing approach showed that N2O mainly originated from bD. Both, 15N label supplied in the form of ammonium and 15N label supplied in the form of nitrate, increased the 15N enrichment of N2O. This pointed to the contribution of other processes than bD. Nitrification activity was indicated by the conversion of small amounts of 15N-labeled ammonium into nitrate.Discussion/ConclusionComparing the results from N2O isotopocule analyses and the 15N tracing approach, likely a combination of bD, nD, and coupled nitrification and denitrification (cND) was responsible for the vast part of N2O emissions observed in this study. Overall, our findings help to better understand the processes underlying N2O and N2 emissions from hydroponic tomato cultivation, and thereby facilitate the development of targeted N2O mitigation measures.

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Would a sustainable city be self-sufficient in food production?

Cited by 7 publications

References 59 publications

A Review of Nutrient Losses to Waters From Soil- and Ground-Based Urban Agriculture—More Nutrient Balances Than Measurements

A Review of Nutrient Losses to Waters From Soil- and Ground-Based Urban Agriculture—More Nutrient Balances Than Measurements

Urban Agriculture as a Sustainable Option for Solid Waste Management: Case Study of an Indian City

Sources of nitrous oxide emissions from hydroponic tomato cultivation: Evidence from stable isotope analyses

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