Benefits of non-commercial urban agricultural practices—a systematic literature review

Citation: Boukharta, O.F.; Huang, I.Y.; Vickers, L.; Navas-Gracia, L.M.; Chico-Santamarta, L. Benefits of Non-Commercial Urban Agricultural Practices—A Systematic Literature Review. Agronomy 2024,14, 234. https://doi.org/10.3390/ agronomy14020234 Academic Editor: Rosa Maria Fanelli Received: 29 December 2023 Revised: 20 January 2024 Accepted: 21 January 2024 Published: 23 January 2024 Copyright: © 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). agronomy Review Benefits of Non-Commercial Urban Agricultural Practices—A Systematic Literature Review Ouiam Fatiha Boukharta 1,* , Iona Yuelu Huang 2, Laura Vickers 3, Luis Manuel Navas-Gracia 1and Leticia Chico-Santamarta 1,4,* 1TADRUS Research Group, Department of Agricultural and Forestry Engineering, University of Valladolid, 47011 Valladolid, Spain; [email protected] 2 Food, Land and Agribusiness Management, Harper Adams University, Edgmond, Shropshire TF10 8NB, UK; [email protected] 3 Agriculture and Environment Department, Harper Adams University, Edgmond, Shropshire TF10 8NB, UK; [email protected] 4Global Impact Department, Harper Adams University, Edgmond, Shropshire TF10 8NB, UK *Correspondence: [email protected] (O.F.B.); [email protected] (L.C.-S.) Abstract: Urban agriculture refers to any type of activity located within or around a city designed to provide ecosystem services. Given the rapid population growth and urbanization, urban agriculture is seen as a potential alternative route to a more sustainable urban food system. This review answers the main question: What are the benefits of non-commercial of Urban Agriculture (NCUA) forms and its contribution towards food production? using a systematic literature review approach. The methodology involved capturing 1355 recent articles from qualified search engines, using key terms according to the defined question, then screened for relevance and the defined scope of this review, resulting in a final selection of 40 articles for analysis. The results show that implementing NCUA practices has multifaced social, economic, and environmental benefits, such as improving people’s health, reducing expenditure on food and creating sustainable cities, highlighting the need to recognize the multifaceted role of NCUA in promoting a more sustainable lifestyle and strengthening local communities and engagement. Moreover, awareness of urban agriculture differs between developed and developing countries, as does the recognition and valorization of its benefits. Further research is needed to examine the enabling factors and barriers to NCUA adoption in different urban context, the resource implications, and the long-term sustainability of these practices. Keywords: non-commercial urban agriculture; benefits; community gardens; school gardens; allotments; urban farms 1. Introduction Ensuring sustainable urban food systems is of extreme importance, given that urban areas are currently characterized by rapid population growth, aggressive food marketing, and unhealthy diets [ 1 ]. Indeed, these areas and their inhabitants face numerous challenges linked to the expansion of urbanization, including socio-economic, ecological, and environmental issues, which have a negative impact on the environment and unsustainable urban development and a huge impact on health [ 2 ]. According to the World Health Organization (2020), we are now in an era of concern for mental health and well-being, in which the presence of green spaces has been shown to reduce the mental health burden associated with depression [ 3 ], affecting more than 264 million people. In addition, cities increasingly need food supplies, but growth of cities is reducing urban and peri-urban green spaces and removing food production. Sustainable food production should therefore be located close to the centers of consumption [4]. To address these challenges, urban agriculture (UA) is seen as a potential solution that can provide green space and bring food production [ 5 ]. Indeed, UA is defined as any type Agronomy 2024,14, 234. https://doi.org/10.3390/agronomy14020234 https://www.mdpi.com/journal/agronomy Agronomy 2024,14, 234 2 of 19 of activity located within or at the periphery of a city and aimed at providing products and ecosystem services to the residents, such as physical and mental health benefits, mitigation of social and economic problems, and community resilience [6]. Many forms of UA are currently being practiced [ 6 ]. In this systematic review, the focus is on NCUA, focusing particularly on urban farms, community gardens, school gardens, and allotments. Community gardens (CG) have been defined as ‘open spaces which are managed and operated by members of the local community in which food or flowers are grown, and whose total area is maintained collectively, ranging from small neighborhood gardens to larger ones of up to 1000 m2’ [6,7]. This is a popular strategy for strengthening social cohesion and improving health [ 1 ]. As far as allotments (A) are concerned, they have been defined as ‘plots of land designated by local authorities for the purpose of growing vegetables for home consumption’ [ 8 ]. A occurs when land is acquired through a personal-use lease [ 8 ]. Nevertheless, when A meet the criteria of growing food or flowers in a communal manner, they can also be considered as CG [ 9 ]. Another form of NCUA are school gardens (SG), which feature vacant land on school sites designed for a range of food education-related agricultural activities involving student participation [ 10 ], which are useful for improving children’s nutritional outcomes and knowledge [ 11 ], making them more willing to try unfamiliar varieties of fruits and vegetables [ 12 ]. In addition, SG provide an opportunity to meet and interact with other students in a natural environment, developing social skills, communication, and cooperation [ 13 ]. The final form of UA that is evaluated in this study is urban farms (UF), which are considered the main source of income for many urban households [ 14 ]. According to the FAO, by 2022, urban and periurban farmers will increasingly strive to produce high-demand crops efficiently, making the best use of available resources and inputs, whether by planting in the ground or in containers [ 4 ]. Moreover, they can provide shelter for birds and beneficial insects, helping to preserve urban biodiversity [15]. The benefits of implementing NCUA practices within the cities have long been demonstrated in the literature, which can be categorized into economic, environmental, and social benefits. The literature considers NCUA to have a number of potential social benefits, including strengthening social capital, increasing social cohesion and community resilience, and improving public health [ 16 ]. Moreover, the positive social effects of being in nature have been shown to increase feelings of generosity, friendship, and empathy [ 17 , 18 ]. Indeed, it reduces personal feelings of anxiety and improves mental health and well-being [ 19 – 21 ]. In terms of economic benefits, a number of studies have shown that the implementation of urban agricultural practices (UAP) helps to reduce the global food supply and demand situation, as it can be seen as a source of income while providing direct access to a wider range of nutritionally rich products [ 22 ]. In other words, UA can generate an additional source of income, improving the economic situation of many households [ 14 ]. The final aspect is that of the environmental, where the outcomes of UA are generally highly valued and recognized by scientists for their great potential to improve the quality of urban life and the environment [ 23 ]. In fact, the creation of UA spaces in cities helps to retain stormwater, purify the air, and conserve biodiversity [ 24 ], thus helping to mitigate the pollutants responsible for global warming [ 25 ]. Moreover, as food is grown and produced locally, it reduces transport costs and ensures environmental protection [26]. In view of continuing population growth, shrinking urban spaces, and increasing food insufficiency, it is worth discussing and examining the NCUA and its current relevance. Although the categories of benefits of NCUA have been presented in existing literature, there is a lack of understanding of the variations in the types of benefits derived from different forms of NCUA and how these benefits may vary in different contexts. To this end, the following main research question (RQ) was defined: What are the benefits of non-commercial forms of Urban Agriculture and its contribution towards food production? To facilitate the understanding and structure of this review, this main question is complemented by the following sub-research questions: Agronomy 2024,14, 234 3 of 19 - RQ1: Which countries have conducted this type of research? And what are the similarities and differences across countries/continents? - RQ2: What forms of NCUA food production have been practiced? - RQ3: What are the similarities and differences reported across different forms of UA? - RQ4: What are the challenges and limitations of implementing UAP faced by the authors of the selected articles in this review? The main objective of this systematic review is therefore to synthesize the evidence on the benefits of NCUA practices, since much of the existing research is case-specific and lacks a comprehensive systematic analysis of the benefits in different contexts and at different scales, such as the lack of awareness of these projects, the benefits they bring to the population and the city, and the feasibility of integrating UAP [ 27 , 28 ]. To this end, and through this review, we aim to summarize the findings and relevance of the available literature, using a systematic mapping, in order to provide an overview of NCUA practices to ensure a healthy and accessible food supply while improving urban environmental performance for current and future generations. Section 2describes the methodology used for this review and presents the main inclusion and exclusion criteria that enabled the final selection of the articles analyzed and coded to answer and address our RQs. Section 3presents the results and conclusions of this analysis, highlighting the different categories of NCUA benefits, the differences between and across countries, along with the difficulties and limitations reported in the selected articles with regard to NCUA implementation. Section 4places these results in a clearer perspective, exploring some of the main implications of the NCUA, taking up the results at a global level and filling in the gaps found in the literature. The final section is the conclusion, in which an overview of the current situation is presented, together with some recommendations that should be followed for better implementation of the future NCUA. 2. Materials and Methods The methodology used in this review follows the systematic literature review process recommended by James et al. (2016). This involved searching for and capturing relevant articles on the topic under review, using key terms derived from the main RQ, and then screening them according to their relevance to the specific topic of this study, and other criteria that will be described further in the following sub-sections. The methodology aimed at ensuring a rigorous, comprehensive, and objective literature collection and filtering processes, in order to reduce reviewer selection and publication bias and guarantee transparency of evidence inclusion decisions [29]. 2.1. Search Strategy The databases consulted included the Web of Science and Scopus search engines. The search terms used were developed on the basis of the key elements of a systematic literature review: population, intervention, and outcomes, where population refers to the object of our study, in this case urban agriculture, intervention refers to the description of the action addressed and the studies, namely food production in this review, and outcomes represent the results we wish to find, which are benefits. In addition, Boolean operators such as “AND” and “OR” were used for the combinations of our keywords for this search, enabling the following string to be formed: ((((urban AND (agricul* OR farm*)) OR “community garden*” OR “school garden*” OR allotment*) AND benef*) AND (food OR fruit* OR veg*)). Details of the components and relevant key terms are presented in Table 1. In terms of components, it shows the different ways in which a keyword can be searched for. For example, in the case of urban agriculture, agriculture can be written in different ways, such as agriculture, agricultural, etc., which is then searched for under agricul*; similarly, benefits, which can be written in different ways, such as benefit, benefits, beneficial, etc., to avoid missing information, is searched for under benef*. This is the best way to be sure of obtaining all the relevant information needed to address our problem. Agronomy 2024,14, 234 4 of 19 Table 1. Search terms used in Scopus and Web of Science. Components Key Terms Population urban agricul*—urban farm* urban AND (agricul* OR farm*) school garden—school gardens “school garden*” community garden—community gardens “community garden*” allotment* Intervention food production food OR fruit* OR Veg* Outcomes benefit—benefits—beneficial— benefic—etc. benef* 2.2. Inclusion and Exclusion Criteria The inclusion criteria for this review were articles and early accepted articles published in English between 2016 and 17 January 2023 to ensure that the review included the most recent literature on the subject, given that the growing interest in UAP and their implementation in cities has improved since 2016, and increased significantly from 2020. No country limitation was used, as the aim was to carry out a global review. The specific inclusion and exclusion criteria presented in Table 2were applied manually for screening at title and abstract and at full text. If the criteria could not be applied at title and abstract screening due to incomplete information, they were included for full text screening. Table 2. Inclusion and exclusion criteria. Criterion Eligibility Exclusion Document type Articles and early accepted articles Conference papers, book chapters, reviews, editorials, conference reviews, Open and non-open access full text articles not accessible Language English Others Timeline From January 2016 until 17 January 2023 Before 2016 Relevance Non-commercial urban agriculture Commercial urban agriculture Type of articles Empirical paper with primary findings about the benefits of NCUA Review papers, commentaries, or primary studies with no benefits reported 2.3. Data Extraction and Analysis The search and selection process identified 1754 articles from the Web of Science and Scopus search engines. After deleting 399 duplicates, the total number of articles selected was 1355. After applying the inclusion criteria by selecting articles and early accepted articles in open and non-open access, all in English between 2016 and 17 January 2023, as well as the exclusion criteria, excluding conference papers, book chapters, etc., directly from Web of Science and Scopus via the selection filters provided on their web pages, and then checking the resulting data and eliminating articles that do not meet our selection criteria, 45 articles were deemed eligible for results mapping. When coding and analyzing each article, 5 articles were excluded: 2 for including commercial UAP, 2 for not including any NCUA content, and 1 for not including any NCUA benefits, which resulted in a final selection of 40 articles for analysis. The diagram illustrated in the PRISMA Figure 1 demonstrates in detail the process and results of screening stage by stage. Agronomy 2024,14, 234 5 of 19 Agronomy 2024, 14, x FOR PEER REVIEW 5 of 20 selection of 40 articles for analysis. The diagram illustrated in the PRISMA Figure 1 demonstrates in detail the process and results of screening stage by stage. Figure 1. The PRISMA 2020 flow diagram of the systematic literature review process (adapted from Page et al., 2020 [30]). A qualitative synthesis approach was adopted to map the results of the included articles. For this purpose, the software used in the present review is NVivo, one of the most used qualitative data management programs. NVivo has features such as character-based coding, rich text capabilities, and multimedia functions that are crucial for qualitative data management [31]. In addition, it enables researchers to process large amounts of data with greater transparency and provides opportunity for double-checking the reliability of coding by members of the research team [32]. Figure 1. The PRISMA 2020 flow diagram of the systematic literature review process (adapted from Page et al., 2020 [30]). A qualitative synthesis approach was adopted to map the results of the included articles. For this purpose, the software used in the present review is NVivo, one of the most used qualitative data management programs. NVivo has features such as character-based coding, rich text capabilities, and multimedia functions that are crucial for qualitative data management [ 31 ]. In addition, it enables researchers to process large amounts of data with greater transparency and provides opportunity for double-checking the reliability of coding by members of the research team [32]. 3. Results The following sections present the results obtained from this review, which clearly answer our main RQ and the sub-questions. It should be noted that across the articles obtained, there is a steady increase in the number of articles published per year, with Agronomy 2024,14, 234 6 of 19 accelerated progression from 2020 to 2023, showing that the concept of UA has become more popular in recent years, and that interest in its application is growing. 3.1. Study Sites Location From the included papers, Figure 2shows the number of articles from different countries using a map to facilitate data analysis and processing the country distribution of the selected studies using a bar chart indicating the number of articles published by each country: Agronomy 2024, 14, x FOR PEER REVIEW 6 of 20 3. Results The following sections present the results obtained from this review, which clearly answer our main RQ and the sub-questions. It should be noted that across the articles obtained, there is a steady increase in the number of articles published per year, with accelerated progression from 2020 to 2023, showing that the concept of UA has become more popular in recent years, and that interest in its application is growing. 3.1. Study Sites Location From the included papers, Figure 2 shows the number of articles from different countries using a map to facilitate data analysis and processing the country distribution of the selected studies using a bar chart indicating the number of articles published by each country: Figure 2. Location of the study sites identified from the 40 articles analyzed in this systematic literature review, represented on a world map featuring a heatmap showing the number of articles published per country (where the darker the color, the more articles exist). Figure 2 shows that there was a very wide distribution of NCUA related studies throughout this research, in which it can be seen that around 30 countries were analyzed. Figure 2 also presents a heatmap showing the frequency of articles published by country, where the darker the color, the more articles were published. It can be seen that USA and Canada have the highest number of published articles in this overview. Figure 2 is complemented by Figure 3, which illustrates in greater detail the countries where the most UAP have been analyzed: Figure 2. Location of the study sites identified from the 40 articles analyzed in this systematic literature review, represented on a world map featuring a heatmap showing the number of articles published per country (where the darker the color, the more articles exist). Figure 2shows that there was a very wide distribution of NCUA related studies throughout this research, in which it can be seen that around 30 countries were analyzed. Figure 2also presents a heatmap showing the frequency of articles published by country, where the darker the color, the more articles were published. It can be seen that USA and Canada have the highest number of published articles in this overview. Figure 2is complemented by Figure 3, which illustrates in greater detail the countries where the most UAP have been analyzed: Agronomy 2024, 14, x FOR PEER REVIEW 6 of 20 3. Results The following sections present the results obtained from this review, which clearly answer our main RQ and the sub-questions. It should be noted that across the articles obtained, there is a steady increase in the number of articles published per year, with accelerated progression from 2020 to 2023, showing that the concept of UA has become more popular in recent years, and that interest in its application is growing. 3.1. Study Sites Location From the included papers, Figure 2 shows the number of articles from different countries using a map to facilitate data analysis and processing the country distribution of the selected studies using a bar chart indicating the number of articles published by each country: Figure 2. Location of the study sites identified from the 40 articles analyzed in this systematic literature review, represented on a world map featuring a heatmap showing the number of articles published per country (where the darker the color, the more articles exist). Figure 2 shows that there was a very wide distribution of NCUA related studies throughout this research, in which it can be seen that around 30 countries were analyzed. Figure 2 also presents a heatmap showing the frequency of articles published by country, where the darker the color, the more articles were published. It can be seen that USA and Canada have the highest number of published articles in this overview. Figure 2 is complemented by Figure 3, which illustrates in greater detail the countries where the most UAP have been analyzed: Figure 3. Cross-country distribution of articles analyzed in this review. According to Figure 3, the largest number of articles are found in USA, Australia, Canada, UK, and EU countries. In addition, other African and Asian countries are also Agronomy 2024,14, 234 7 of 19 implementing UA, such as Morocco and Malaysia, demonstrating that NCUA is now a global concept that is increasingly widespread around the world (particularly in more developed countries), given the benefits it provides. 3.2. NCUA across Continents In North America, food insecurity affected around 14.3 million people in 2018 [ 33 ]. Consequently, NCUA has become very popular in New York City, which has at least 500 urban spaces [ 34 ]. The aim is to improve access to fresh produce for city dwellers, especially the food-insecure, and has been attributed to tackling poverty and food shortages in times of war and economic depression [35]. In Australia, rapid population growth and ageing in capital cities are increasing pressure on social, environmental, and public health systems, where one in four Australians experience chronic episodes of loneliness [ 10 ]. Australian local authorities are therefore coordinating their efforts to improve the urban canopy within the cities, which would offer significant opportunities to improve well-being [36]. The NCUA situation in Europe differs from country to country: Germany is a typical European country where NCUA is about much more than just food production, and where there is an appreciation of the benefits NCUA brings to citizens, through active participation in European Union projects [ 37 ]. In the UK, therapeutic and prescriptive gardening is gaining increasing support to help people overcome or live with mental health problems [ 9 , 38 ]. In Spain, CG have only emerged recently and are developing rapidly. In Croatia, urbanization, environmental issues, the future development of tourism, and social issues (mental health, unhealthy diet, and poverty) are behind the development of UA [ 39 ]. In North Africa, Morocco has an agricultural strategy adopted in 2008, known as the Plan Maroc Vert (Green Morocco Plan, in English), and whose second pillar supports smalland medium-sized farmers so as to encourage the implementation of NCUA within the cities [ 40 ]. Finally, in South Africa, several studies have been conducted to assess the role of NCUA in contributing towards poverty alleviation and food security [41]. 3.3. Forms of NCUA Identified Many forms of NCUA can be implemented in a city, including community gardens (CG), allotments (A), school gardens (SG), and urban farms (UF) [ 3 ]. In this section, the aim is to map the different forms of NCUA studied in different countries on the basis of the articles selected, processed and analyzed in this review. To this end, Figure 4presents the result of the cross-tabulation analysis of the forms of NCUA identified in the studies carried out in the selected countries. Figure 4shows that the most widespread form of NCUA found from the selected articles is CG, with 29 articles out of 40, followed by UF and then A and SG (this analysis considered that the same study can deal with several forms of NCUA at the same time). Other forms of NCUA reportedly used are rooftop gardens, backyard gardens, etc., but these were not part of the selection criteria of this review. These results show that there is a diversity in the implementation of different forms of NCUA within countries, differing from a country to another, as explained in Section 3.4. 3.4. Forms of NCUA by Countries CG is an abundant form of UA. Figure 4shows that of the 11 articles analyzed in the USA, 10 address CG cases, while in Australia and Spain, CG cases are found in all the articles analyzed from these two countries. For the other countries, only 3 of the 18 categories selected do not contain that form of NCUA in their analysis. Regarding UF, it is the second frequently used NCUA form in this review, which is most widely used in multi-countries (studies that evaluated more than one country), followed by Italy and USA. Finally, UF, A, and SG forms were the least used in the selected articles for this review. Agronomy 2024,14, 234 8 of 19 Agronomy 2024, 14, x FOR PEER REVIEW 8 of 20 Figure 4. Cross-tabulation of NCUA forms implemented across the countries evaluated in the selected articles of this review. A: allotments; CG: community gardens; SG: school gardens; UF: urban farms. Colors: red: no articles mentioning the form of NCUA practices; yellow: low; dark yellow: medium; light green: high; dark green: very high (Source: the authors). Figure 4 shows that the most widespread form of NCUA found from the selected articles is CG, with 29 articles out of 40, followed by UF and then A and SG (this analysis considered that the same study can deal with several forms of NCUA at the same time). Other forms of NCUA reportedly used are rooftop gardens, backyard gardens, etc., but these were not part of the selection criteria of this review. These results show that there is a diversity in the implementation of different forms of NCUA within countries, differing from a country to another, as explained in Section 3.4. 3.4. Forms of NCUA by Countries CG is an abundant form of UA. Figure 4 shows that of the 11 articles analyzed in the USA, 10 address CG cases, while in Australia and Spain, CG cases are found in all the articles analyzed from these two countries. For the other countries, only 3 of the 18 categories selected do not contain that form of NCUA in their analysis. Regarding UF, it is the second frequently used NCUA form in this review, which is most widely used in multi-countries (studies that evaluated more than one country), followed by Italy and USA. Finally, UF, A, and SG forms were the least used in the selected articles for this review. 3.5. Methodology Employed and Its Link to NCUA Forms Understanding the methodology employed to analyze the different NCUA forms is one of the main objectives of this review. The following subsections will present different results extracted from the analysis carried out via coding in NVivo 14 Software: Figure 4. Cross-tabulation of NCUA forms implemented across the countries evaluated in the selected articles of this review. A: allotments; CG: community gardens; SG: school gardens; UF: urban farms. Colors: red: no articles mentioning the form of NCUA practices; yellow: low; dark yellow: medium; light green: high; dark green: very high (Source: the authors). 3.5. Methodology Employed and Its Link to NCUA Forms Understanding the methodology employed to analyze the different NCUA forms is one of the main objectives of this review. The following subsections will present different results extracted from the analysis carried out via coding in NVivo 14 Software: 3.5.1. Methodologies Used for the Realization of the Article Identifying the different research methods used in each of our 40 articles provides a better understanding of the type of research methods employed to analyze the benefits of NCUA, as shown in Figure 5: Figure 5shows that the most commonly used research methods approach adopted is the survey to collect data for analysis. Surveys were used in 15 articles out of 40 (37%), followed by interviews and observation with 7.5% each, and finally the experimental method with 5%. The use of the mixed method is the most interesting. Indeed, it indicates that the most frequent approach in the articles was to use a mixture of research methods. The percentage breakdown of the mixed method is presented in more detail in Figure 6. In these 17 articles out of 40, surveys have the highest percentage of use, followed by interviews, and finally observation and experimentation (Figure 6). The results show that the joint use of surveys and interviews to analyze NCUA forms is favored for analysis, and can be supplemented by observation and/or experimentation, making understanding and evaluation more precise. Agronomy 2024,14, 234 9 of 19 Agronomy 2024, 14, x FOR PEER REVIEW 9 of 20 3.5.1. Methodologies Used for the Realization of the Article Identifying the different research methods used in each of our 40 articles provides a better understanding of the type of research methods employed to analyze the benefits of NCUA, as shown in Figure 5: Figure 5. Number of articles that employed exclusively each research methodology in the selected articles, except for the mixed category which is where articles employed more than one research method. Figure 5 shows that the most commonly used research methods approach adopted is the survey to collect data for analysis. Surveys were used in 15 articles out of 40 (37%), followed by interviews and observation with 7.5% each, and finally the experimental method with 5%. The use of the mixed method is the most interesting. Indeed, it indicates that the most frequent approach in the articles was to use a mixture of research methods. The percentage breakdown of the mixed method is presented in more detail in Figure 6. Figure 6. Frequency of use of each search method in articles using the mixed search method. In these 17 articles out of 40, surveys have the highest percentage of use, followed by interviews, and finally observation and experimentation (Figure 6). The results show that the joint use of surveys and interviews to analyze NCUA forms is favored for analysis, and can be supplemented by observation and/or experimentation, making understanding and evaluation more precise. Figure 5. Number of articles that employed exclusively each research methodology in the selected articles, except for the mixed category which is where articles employed more than one research method . Agronomy 2024, 14, x FOR PEER REVIEW 9 of 20 3.5.1. Methodologies Used for the Realization of the Article Identifying the different research methods used in each of our 40 articles provides a better understanding of the type of research methods employed to analyze the benefits of NCUA, as shown in Figure 5: Figure 5. Number of articles that employed exclusively each research methodology in the selected articles, except for the mixed category which is where articles employed more than one research method. Figure 5 shows that the most commonly used research methods approach adopted is the survey to collect data for analysis. Surveys were used in 15 articles out of 40 (37%), followed by interviews and observation with 7.5% each, and finally the experimental method with 5%. The use of the mixed method is the most interesting. Indeed, it indicates that the most frequent approach in the articles was to use a mixture of research methods. The percentage breakdown of the mixed method is presented in more detail in Figure 6. Figure 6. Frequency of use of each search method in articles using the mixed search method. In these 17 articles out of 40, surveys have the highest percentage of use, followed by interviews, and finally observation and experimentation (Figure 6). The results show that the joint use of surveys and interviews to analyze NCUA forms is favored for analysis, and can be supplemented by observation and/or experimentation, making understanding and evaluation more precise. Figure 6. Frequency of use of each search method in articles using the mixed search method. 3.5.2. The Methodology Used for Each NCUA Form One of the main purposes of this systematic review is to analyze the relationship between the different forms of NCUA and the research methodology used. To this end, Figure 7details the methodology used for each UA form. Agronomy 2024, 14, x FOR PEER REVIEW 10 of 20 3.5.2. The Methodology Used for Each NCUA Form One of the main purposes of this systematic review is to analyze the relationship between the different forms of NCUA and the research methodology used. To this end, Figure 7 details the methodology used for each UA form. Figure 7. Number of articles that used each research methodology, related to the form of non-commercial Urban Agriculture Practice evaluated. Figure 7 shows that several research methods are used to analyze the implementation of NCUA in cities and the resulting benefits, i.e., through interviews, surveys, experiments, observations, or even a mix of these methods employing at least two of them, making the analysis more precise and comprehensive. Experimental methodology is the least used in the articles selected, and was used in only 2 articles out of 40. For interviews and observation, four and three articles, respectively, used only these methods to obtain results. Once again, the methodology most used in our 40 articles is the mixed method, which is employed for the majority of UA forms, where CG is the most analyzed with this approach, followed by UF, SG, and A. These results show us the diversity of existing research methodologies employed for analyzing the use of UA and the benefits they bring, and shows preference for some research strategies over others. 3.6. Benefits of the Implementation of NCUA Practices Identifying the benefits that NCUA practices bring is the main objective of this review article. Indeed, in-depth coding of the selected articles has resulted in the cross-tabulated table shown in Figure 8, which was obtained from NVivo 14 Software, and where the green color refers to the highest number of studies and the red color to the lowest number. Figure 7. Number of articles that used each research methodology, related to the form of noncommercial Urban Agriculture Practice evaluated. Figure 7shows that several research methods are used to analyze the implementation of NCUA in cities and the resulting benefits, i.e., through interviews, surveys, experiments, Agronomy 2024,14, 234 16 of 19 results and openness around the world. The present study is one of the first to illustrate the perceived benefits of NCUA to both the population and the city itself, improving cities and making them more sustainable and resilient. However, we suggest that further research should be carried out in the future to further explore and understand this discipline which is currently of great importance to current and upcoming generations, using more critical appraisal of study design and contextual information which may produce more nuances into the variances of findings. Author Contributions: Conceptualization, O.F.B., L.M.N.-G. and L.C.-S.; methodology, O.F.B. and I.Y.H.; software, O.F.B. and I.Y.H.; validation, L.C.-S., L.M.N.-G. and L.V.; formal analysis, O.F.B., I.Y.H., L.C.-S., L.V. and L.M.N.-G.; investigation, O.F.B., I.Y.H., L.M.N.-G. and L.C.-S.; resources, L.M.N.-G. and L.C.-S.; writing—original draft preparation, O.F.B.; writing—review and editing, O.F.B., L.C.-S., L.M.N.-G., I.Y.H. and L.V.; visualization, O.F.B., L.C.-S., L.M.N.-G. and L.V.; supervision, I.Y.H., L.C.-S., L.M.N.-G. and L.V.; project administration, L.M.N.-G.; funding acquisition, L.M.N.-G. and L.C.-S. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by the European Union supporting this work through the FUSILLI Project (H2020-FNR-2020-1/CE-FNR-07-2020), grant number No. 101000717; website: https://fusilli-project.eu/ (accessed on 1 January 2024). Data Availability Statement: Not applicable. Acknowledgments: Ouiam Fatiha Boukharta has been financed under the call for University of Valladolid 2021 predoctoral contracts, co-financed by Banco Santander. Conflicts of Interest: The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. List of Abbreviations A allotments CG community gardens NCUA non-commercial urban agriculture RQ research question SG school gardens UA urban agriculture UAP urban agricultural practices UF urban farms References 1. 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