4.1. Several Agriculture Models and Urban Agriculture under Different Socio-Economic Contexts
Academic focus on urban agriculture is primarily inconsistent among the developed and developing world and different farming models. Having fewer than twice the scholarly journal articles in developed countries reveals that the academic attention on urban agriculture in developing countries is still limited, despite having favorable agriculture activities. Regardless of the potential importance of urban agriculture in developing countries, the practice has still not been synthesized sufficiently in the global academic literature [
75]. However, the extensive literature on urban agriculture in developing countries can be found in nonscientific sources, such as technical documents, technical bulletins, and project reports [
13]. Published academic information is considered highly reliable as they are subjected to be mandatorily reviewed by other scholars in the same academic discipline. Therefore, producing more scientific data on urban agriculture in developing countries is essential to encourage urban agriculture to create sustainable urban environments. There is also a significant difference among urban agriculture models recorded in the reviewed articles. The majority of articles recorded community gardens and few numbers with other models. In developed countries, the highest registered agriculture model was community gardens or allotment gardens; this academic favoritism had been recorded in former studies [
26,
76,
77]. There is a significant void in the empirical studies on home food gardens; even academic literature on urban agriculture in the developed world is rapidly expanding [
28]. However, some studies emphasize that more attention and studies on home gardens are required, such as the specific potential and contribution of home gardens, the influence of the urban environment and socio-demographic characteristics, and gardeners’ motivation [
78]. Therefore, more academic knowledge on the opportunities and challenges of different urban agriculture models is needed to identify suitable farming models under different contexts.
4.2. Contribution of Studies on Urban Agriculture
The most popular academic attention is the identification of the benefits of urban agriculture. However, the academic attention of both developed and developing countries has considered the multifunctionality of urban agriculture. In the meantime, these multiple benefits showed differences among the country’s socio-economic context and type of agriculture model. People’s motivations in developed countries tend to favor social, health-related, and educational benefits of urban agriculture; however, urban agriculture is more related to economic and ecological needs in developing countries. This preference has been proven by many other scholars as well [
79,
80]. Among farming intentions in urban agriculture practices in developed countries, social and educational farming are more frequent in Europe, Oceania, and North America. At the same time, few cases of commercial projects are significant in Japan [
13]. Another general observation is the diversity of benefits provided by community gardens compared to other models. It was also seen that even large-scale commercial farms could provide multiple non-cash benefits [
64]. Therefore, different agricultural models need to be studied thoroughly on their multifunctionality.
According to the review results, the topmost recorded social relation benefits are “social interactions” and “recreation.” This implies an excellent opportunity to link urban agriculture with urban planning as spaces that provide opportunities for social interactions and recreation within urban contexts. Community-generated social spaces have become key places in urban areas for gatherings and enhance social interactions between communities [
81]. It is commonly believed that developing countries focus more on the economic benefits of urban agriculture than the developed countries. But in the present review, we found that both developing and developed countries have given similar weight to the economic benefits, even though there are some slight differences. The Food and Agriculture Organization of United Nations points out that sustainable urban agriculture models should be profitable and economically viable [
1]. Hence, the economic perspective is critical for the long-term sustainability of urban agriculture despite the socio-economic context. However, the most cited economic benefits of urban agriculture are food production and food security, providing income sources, and reducing household food expenditure. Therefore, it is important to consider these economic motivations when agriculture practices are encouraged in urban environments.
It was also noticed that developed and developing countries have different intentions regarding the production of urban agriculture. Developed countries mainly intended to gain nutrition and quality food, whereas developing countries were more concerned with food production and food security. Understanding these differences in personal motives and intentions is important to integrate urban agriculture with urban planning in cities with different socio-economic contexts. It is widely understood that urban agriculture plays a critical role as a survival strategy for the urban poor in improving food security and healthy nutrition for urban society [
80,
82,
83]. Practicing as a land management strategy in urban areas is one of the main ecological benefits of urban agriculture in many situations. In cities, agriculture can be used for landscape beautification [
21,
22,
76], to enhance greenery [
26,
49,
68], for urban restoration [
59] and regeneration [
55,
77], to maintain public spaces [
73] as well as to utilize urban vacant lands [
12,
53,
84]. However, other ecological benefits also need to be studied in more detail, especially in developed countries, to integrate agriculture with urban planning in a sustainable manner.
Climate resilience is the least recorded benefit regarding urban agriculture. Only five papers recorded this benefit by way of flood control, micro-climate regulation, climate action, and reduction of food miles [
5,
9,
47,
64,
80]. Having a limited academic focus on climatic benefits, perhaps due to climate resilience in cities, is considered more general and not thoroughly considering urban agriculture. Previous studies have proven that urban agriculture helps urban flood control through water retention by vegetation and unpaved surfaces, and reduces the urban heat island effect, increasing the air humidity through evapotranspiration [
85]. Some scholars imagine the city of the future as resilient and self-sufficient, which reaches the “ecosystem stage” via urban agriculture [
79]. Therefore, to achieve a resilient urban future, studying the role of urban agriculture in climate resilience in a comprehensive manner might be useful.
Urban agriculture can support vulnerable groups in the city, such as elderly people, migrants, minorities, low-income people, and people with mental disorders. In the present review, elderly people have been recognized as the leading benefited group, especially in developed countries. Identifying actual beneficiaries in each urban agriculture practice is crucial to efficiently integrate urban agriculture into urban planning because inconsistency between actual usage and planning intention has been identified as one of the significant reasons that urban agriculture has been limitedly used in policy and planning [
86]. Identification of land ownership of agriculture practices in cities is important for the long-term sustainability of urban agriculture. According to the results, government lands play an important role in urban agriculture activities; they can be utilized two ways in urban farming: use with formal agreements [
12,
38,
69] and use without any formal agreements, which includes using sidewalks and median strips for farming [
12]. However, sometimes, utilizing government lands can make agriculture activities less sustainable, as there is no security of permanence due to other urban development pressures [
63]. To support urban agriculture, some countries develop land-use policies to integrate natural urban ecosystems, such as wetlands with urban agriculture [
10]. However, public–private collaborations might be helpful to improve the efficiency and sustainability of urban agriculture, especially in situations when sizeable public expenditure for operations can be a barrier to use state lands for agriculture [
69].
Government support is vital for the sustainability of urban agriculture practices in cities. The reviewed articles depict this support as mainly including support given by municipal councils or local governments and policies to integrate agriculture into urban planning. High financial and institutional support can make urban agriculture activities more secure in cities [
87]. However, the attention on government initiatives in academic literature is limited and significantly less in developing countries. More academic attention on government support in developed countries reveals their interest in urban agriculture to create urban sustainability.
Land security is the most frequently recorded challenge that can directly influence the long-term sustainability of urban agriculture, which has been proven by many previous studies [
87,
88,
89]. Land insecurity can incentivize rent-seeking behavior, and therefore, urban agriculture is at risk of highest and best use developments [
90]. In addition, lack of time and consistent interest are two common human-related challenges recorded in both developed and developing countries. Buying inputs, mainly seeds and fertilizer, is the main common financial challenge registered in developed and developing countries [
12,
28,
42]. Irrigation can be a challenge in cities, as urban water is expensive, and this can cause insecurities in urban agriculture [
87]. Therefore, urban agriculture should move towards innovative sustainable irrigation solutions, such as the re-use of wastewater [
91,
92]. Identification of challenges for each case through proper scientific investigations is important as they are highly dependent on local factors.
4.3. Lessons to Be Learned from Each Other
The results demonstrated that a country’s socio-economic context influences the types of benefits yielded from urban agriculture practices, which have been proven by many studies. Our comparison between developed and developing countries is not only useful to understand the influence of socio-economic context on urban agriculture activities but also to learn best practices in the application of urban agriculture in urban planning to improve the well-being of urban citizens. With the growing trend of introducing urban agriculture into urban planning in both developed and developing regions, this learning could efficiently integrate urban agriculture into urban planning.
Developed countries focus more on how urban agriculture can be used as a strategy in urban planning to enhance citizens’ social and health well-being. According to the present review, it is revealed that developed countries significantly consider the potential of using urban agriculture as preventive health care measures in urban setups. It is primarily recognized that regular contact with nature provides many health benefits and enhances psychological well-being [
35]. Generally, people living in highly urban areas and more minor natural regions would like to spend more time in urban gardens to get personal satisfaction, mental and physical health, and connect with nature [
58,
93]. Many cities in developing countries are experiencing several adverse impacts due to rapid urbanization, which has created severe negative effects on urban citizens. The lessons from developed countries on how urban agriculture has been utilized to improve the well-being of people could be beneficial for developing countries.
One of the primary functions of urban agriculture in developed countries is creating social interactions and recreation. According to Alderfer’s ERG Theory of Motivation, social motivations are among the three reasons people need for relationships [
94]. In addition, integrating urban agriculture and urban recreation can be beneficial synergies. It can provide additional income opportunities for farmers and farming in cities to create cultural ties between urban citizens with the urban hinterlands [
95]. Another lesson that can be learned from developed countries is utilizing urban agriculture as education centers in the cities, which provide opportunities to learn about gardening, food, nature, sustainability, and develop skills and knowledge of urban citizens. Urban agriculture supports sustainability objectives and promotes environmental stewardship by urban people [
96]. Developing countries can learn more from community garden practices, which is the most popular urban agriculture practice in developed countries to integrate the multifunctionality of urban agriculture to enhance the social well-being of urban citizens. In developed countries, community gardens are not merely places that provide sources for food, they provide other benefits such as social cohesion, community building education, and promoting health [
97,
98,
99]. Other community gardens can be used as places in cities that create social integrity. In general, community gardens are more heterogeneous in education, age, gender, and financial status, and usually lack previous gardening experience [
100].
Many studies from developed countries demonstrated the importance of government support to promote urban agriculture, which could be lessons for developing countries. Local authorities such as municipal councils can play a significant role in the sustainability of urban agriculture practices in cities, as they have the authority to plan and manage the urban lands in most cities [
37,
48,
54]. Integrating urban agriculture into urban planning in Singapore [
26] and Barcelona [
49], establishing legislation to use public lands for urban agriculture in New York [
33], the Workers’ Allotment Gardens Act, and the Polish Association of Allotment Gardens (PZD) in Poland [
51] are some of the examples from the developed world how policy interventions are important to promote urban agriculture. Case studies from Glasgow and Toledo explain the importance of getting informal support from politicians for urban agriculture projects to promote urban farming in cities [
34,
47].
Some important lessons can be learned from urban agriculture practices in developing countries as well. Since developing countries usually concentrate more on the economic benefits of urban agriculture, the others can learn about the multiple economic benefits urban farming can provide for cities. A study conducted in the city of Quito, Ecuador, revealed that home gardening had influenced increased house value [
62]. Moreover, many case studies in developing countries explained the multiple benefits that home gardens provide, limitedly studied in developed countries. Some of the developing countries use urban agriculture as a solution for urban solid waste management (e.g., Bedelle in Ethiopia, Johannesburg in South Africa, and Mexico City) as well as depollution of wastewater (e.g., Mexico City and Antananarivo, Madagascar) [
9,
21,
63,
67]. This demonstrates the potential of using urban agriculture as a low-cost decentralized technique for urban waste management.
4.4. Urban Agriculture on Policy Implementation
There is an excellent opportunity for urban planners to enhance city sustainability by incorporating urban agriculture into the planning agenda at all levels, from the master plan to individual plans, such as sites and neighborhoods [
4]. There are vivid examples of how urban agriculture has been implemented at the policy level in urban planning. In Dae es Salaam in Tanzania, urban agriculture is mainstreamed in land use planning [
79], whereas in Germany, urban agriculture is compulsory in the urban planning process [
101]. The American Planning Association has also recognized the importance of integrating urban agriculture into urban planning [
102]. Havana, Cuba, has allocated 30,000 hectares within and on the fringe of the city [
102]. The city council of Bulawayo, the second-largest city in Zimbabwe, has recognized the importance of urban agriculture to improve access to healthy food for the urban poor, hence have allocated 450 hectares of vacant municipal lands permanently for urban agriculture to disadvantaged urban residents [
80].
Nevertheless, even though urban agriculture is essential in urban resilience and global sustainability [
96], urban land use planning is still underestimating the potential of the multifunctionality of urban agriculture as a nature-based solution [
15]. Further, the potential provision of multifunctionality of urban agriculture is still not adequately accounted for in practice and thus does not positively influence land-use planning in urban areas, and this is considered as one of the great difficulties urban agriculture faces, especially in the global south [
96]. Therefore, a deep understanding of urban agriculture practices under different contexts is vital for the successful implementation of urban agriculture in urban planning decisions.