Evolution of Urban Agriculture in Mexico

According to the 2022 Agricultural Census, the area used or designated for agricultural purposes in Mexico totaled 103.6 million hectares. Of this area, 29.8 million hectares were designated for agricultural use. In terms of production, 34.6 million tons of the principal grains produced in the country were obtained. Furthermore, the census reported that 26.9 million people comprised the agricultural labor force (^{INEGI, 2022}). However, INEGI statistics did not provide information on the percentage of agricultural production obtained through UA techniques, which may be insignificant.

UA in Mexico has deep roots in Mesoamerican cultures, which developed diverse and complex agricultural systems, such as the milpa and the chinampa, adapting to local conditions. The arrival of the Spanish introduced significant changes, such as new crops and farming models, displacing small producers. Throughout history, UA has remained a marginal activity, practiced mainly by popular sectors in colonial and republican cities, as well as in urban peripheries by indigenous peoples. Notable examples include the chinamperos of Xochimilco. These agricultural systems combine food, medicinal, ornamental, and ritual crops, generating biodiversity and productivity (^{Bastista et al., 2022}). At the beginning of the last century, and since the Mexican Revolution and the agrarian reform of 1917, public policies have played a fundamental role in shaping the agricultural sector. In recent decades, there has been an increase in government interest in integrating urban development into sustainable urban development strategies. This is reflected in initiatives such as the “Urban Development Program,” derived from the Federal Government’s 2020-2024 Institutional Development Plan, which seeks to incorporate urban development into territorial and urban planning to improve food security and quality of life in cities. Furthermore, it seeks to strengthen institutional capacity and promote sustainability (^{Government of Mexico City, 2022}).

Likewise, urban farming in Mexico has proven to be technically feasible, thanks to the adaptation of practices such as hydroponics and vertical farming, which enable maximizing production in small spaces and with limited resources (^{Succar, 2024}). Furthermore, the implementation of information and communication technologies (ICTs) has facilitated the management and monitoring of urban crops, thus increasing their efficiency and productivity.

Currently, instead of relying on chemical fertilizers, sustainable producers (^{Yúnez and López, 2021}) are turning to biofertilizers and microorganisms that benefit by improving soil health. According to ^{Moreno et al. (2019)}, these microorganisms play a crucial role in the development of more resilient and self-sufficient cities, where food production is carried out responsibly and without compromising the health of the environment. The use of biofertilizers in agriculture, including their application in soil-less cultivation, represents a promising strategy to promote sustainable agricultural practices. By enriching nutrient solutions and fostering a healthy microbial environment, it is possible to improve crop production in an ecological way, aligning with the sustainability and efficiency objectives that characterize both organic agriculture and hydroponic systems. This approach also reinforces the need for continued research to optimize the use of biofertilizers in soilless cultivation contexts, ensuring crop health and the sustainability of the agricultural system in general (^{Federal Government, 2022}).

Public Policies in Mexico that Impact Urban Agriculture

In Mexico, although various related public programs and policies have promoted UA, these have been insufficient and disjointed, thus hindering its development. At the federal level, agricultural policy has prioritized the rural sector and large-scale producers to the detriment of small producers and subsistence production (^{Franco and Lanzaro, 2006}). Notably, censuses conducted by the INEGI (National Institute of Statistics and Geography) provide information on the structure of agricultural production in Mexico, which aids decision-making to create programs that assist these small producers and encourage subsistence production. Social programs and government institutions such as SADER (Secretariat of Agriculture and Rural Development) also produce reports on the distribution of support and subsidies, etc. Furthermore, trade policy has increased food dependency (^{Cotler et al., 2020}). At the state and municipal levels, urban policy has favored industrial and residential development over agricultural spaces, generating conflicts over land use. Lack of coordination and participation has hindered the integration of UA into urban policies (^{Escandón, 2020}).

Among the main state and federal policies worth highlighting, we mention the following:

Within the framework of public policies designed to positively impact UA in Mexico, specific government programs have also been developed to achieve these policy objectives. These programs include:

Climatic and geographical conditions that favor soilless cultivation techniques

Soilless cultivation techniques involve producing plants without using soil as a support medium; instead, inert substrates or nutrient solutions are used, optimizing the use of water and nutrients. To evaluate the technical feasibility and viability of soilless cultivation in Mexico, it is necessary to consider the climatic and geographic conditions that favor or hinder this technique, as well as the socioeconomic aspects that determine its viability and profitability. Some of these factors include:

Moreover, in terms of carbon footprint, soilless cultivation also shows a reduction in greenhouse gas emissions, thanks to the reduced use of heavy machinery and reduced transportation, as production is usually closer to consumption destinations.

In Mexico, water footprint measurement is carried out by institutions such as the Mexican Institute of Water Technology (Instituto Mexicano de Tecnología del Agua, IMTA), which conducts studies to identify water use and evaluate the sustainability of water resource consumption. These studies are essential for understanding the impact of agriculture on the country’s water resources and for promoting more sustainable practices such as soilless cultivation (^{Vázquez del Mercado and Lambarri, 2017}). Thus, water footprint could be an alternative that contributes to urban agriculture in Mexico because of more efficient and sustainable water management. Consequently, soilless cultivation can be considered to represent, not only a response to climatic conditions but also as a proactive strategy to improve the environmental sustainability of urban agriculture in Mexico. The 2020-2024 Sectoral Program, presented to the Federal Government, promotes integrated water management through various activities, such as measuring the water footprint in order to understand water use in different sectors related to urban agriculture in Mexico (^{INECC, 2023}).

Water use efficiency and ecological features

Urban agriculture (UA) contributes significantly to water savings in urban settings. Efficient irrigation techniques, such as drip irrigation, allow for precise water distribution, reducing waste and increasing water efficiency by up to 70% compared to traditional irrigation methods (^{Wikiwater, 2021}). Below, we describe some of the key technical innovations that have been integrated into UA, with the aim of improving cultivation, mitigating environmental impact and reducing energy and water consumption.

Technological innovations and sustainable strategies in cultivation: Hydroponic and Aeroponic techniques

Hydroponic and aeroponic techniques, in the form of advanced soil-less cultivation, have been integrated into urban cultivation to optimize resource use in urban environments. These systems allow plants to be grown in nutrient-rich aqueous solutions or in an environment where the roots are suspended in air, resulting in a significant reduction of water consumption (^{Despommier, 2017}). According to ^{Pomoni et al. (2023)}, water savings can be as high as 90% compared to traditional cultivation.

Another example is the use of energy-efficient LED lighting, commonly used in hydroponics to control the climate, thus reducing energy consumption. A study by ^{Loconsole et al. (2019)} found that using LED lighting in hydroponic systems can reduce energy consumption by up to 60% compared to traditional lighting. The pumps and irrigation systems, essential to hydroponics and aeroponics are designed to be efficient and can operate with reduced energy consumption. Furthermore, by eliminating the need for soil, hydroponic and aeroponic systems require fewer pesticides and herbicides, resulting not only in healthier food but also in more sustainable and environmentally friendly agricultural practices. A study by ^{Otazu (2010)} revealed that aeroponic systems consume only one-tenth to one-thirtieth of the water used in conventional crop production of potatoes for example.

Another innovation in urban agriculture is the implementation of rainwater harvesting systems. These systems allow urban farmers to collect and store rainwater, providing an additional source of irrigation and significantly reducing their dependence on municipal water resources (^{Deng, 2021}). In addition to offering a practical solution to water scarcity, rainwater harvesting also has significant environmental benefits. By capturing and storing rainwater, storm water runoff is reduced, which, in turn, helps mitigate the risk of urban flooding and minimizes soil erosion.

The integration of green roofs and walls into urban agriculture systems represents a comprehensive strategy for improving water efficiency and generating a range of benefits for urban communities (^{Manso et al., 2021}). These structures are not only aesthetically pleasing but also play a crucial role in mitigating several urban environmental problems.

Technical feasibility of Protected Agriculture in Mexico

Due to the lack of technical, financial, and regulatory support, as well as competition for land, water and energy, and challenges related to environmental pollution and health risks, a comprehensive assessment of the technical and economic feasibility of urban urbanization is imperative (^{Zimmerer et al., 2021}); (^{Orsini, 2020}); (^{Kennard and Bamford, 2020}). This assessment involves analyzing the capacity and viability of producing food efficiently and sustainably in urban environments. Technical, economic, and environmental aspects affecting energy and water consumption and savings, as well as the costs and benefits associated with the production, processing, marketing, and consumption of agricultural products, must be considered. In this context, the relationship between the number of protected agriculture facilities and the area they cover in hectares is presented for each state of the Mexican Republic, during the period from 2011 to 2014 (Table 2), according to research conducted by ^{De Anda and Shear (2017)}. The information presented highlights the distribution and density of protected agriculture facilities in different states of the country, providing an overview of the adoption of these practices in various regions.

The 2022 census conducted by INEGI Agropecuario (INEGI Agricultural Institute) mentions protected agriculture (PA) as a productive system that appears to have expanded throughout the country. The use of technology and infrastructure has helped to address environmental factors and provide effective plant protection, by helping curtail pests and diseases, thereby improving crop yields. In Mexico, 30,179 production units practice PA, covering an area of 77,417 hectares; notably, 35 out of every 100 production units are located in the State of Mexico (^{INEGI, 2022}). Figure 1 shows the types of facilities used in protected agriculture, in relation to surface area:

Source: INEGI, 2020

Figure 1 Types of facilities for protected agriculture. 

According to INEGI, these are the types of crops that benefited from AP during the period from October 2021 to September 2022 (Table 3); vegetables and fruit are predominant.

In order to evaluate the net economic benefit per plant, a comparison is made of energy savings, water consumption, costs and benefits, between Mexico and other countries that practice UA with soilless cultivation (Table 4).

From table 4, it is possible to deduce the following:

In this sense, it is important to make a comparison of water consumption, energy consumption and water use efficiency (^{Pomoni et al., 2023}), of crops with soil, compared to crops without soil (Table 5), particularly Hydroponic and Aeroponic crops without soil (Albrigth, 1990).

Comparison with Existing Literature

An analysis of the reviewed articles shows a trend towards sustainability and efficiency in urban agriculture and protected agriculture, by introducing hydroponic and aeroponic crops. For example, ^{Morrison (2020)} highlights the importance of agricultural transformation in the Urban Food Agenda, which is consistent with the findings of ^{Orsini (2020)}, who demonstrated the potential of rooftop gardens for food security and biodiversity in urban environments. These results coincide with those obtained by ^{Savvas and Gruda (2018)}, who reviewed soil-less cultivation technologies, highlighting their efficiency in terms of water use and production.

Practical Implications

The implementation of urban agriculture practices in Mexico presents a less than encouraging outlook due to the lack of public policies. However, its presence is increasingly noticeable in Mexico City and surrounding areas. According to ^{Ávila (2019)}, the city government has implemented support programs, such as the Small-Scale Urban Agriculture program, to promote these practices. A notable example is Xochimilco, where traditional agricultural techniques are being revitalized and microenterprises are being developed that supply products to gourmet restaurants. Similar initiatives are also being undertaken in other regions of Mexico. In Puebla and Tlaxcala, urban production spaces have also been established to supply organic markets. In Monterrey and Guadalajara, urban gardens have been created to meet the demands of local gastronomy. Likewise, in places like Xalapa and Oaxaca, organic food production is being promoted and advice is being offered for the creation of home gardens. Finally, in Chiapas, significant development of peri-urban agriculture has been documented. In summary, according to ^{Ávila (2019)}, urban and peri-urban agriculture in Mexico, not only contributes to food security and economic development, but also strengthens community networks and promotes environmental sustainability.

Challenges and Future Considerations

^{Deng (2021)} raises concerns about pollution in rainwater capture, which represents a challenge for the sustainability and resilience of urban agriculture. This underscores the need to consider water quality, when planning urban agricultural systems. However, ^{Pomoni et al. (2023)} compare hydroponics and conventional agriculture, highlighting the advantages of hydroponics in terms of land use efficiency and reduced water consumption, although they note that it requires more energy and greater initial investment.

Feasibility and Viability of UA in Mexico

Analysis of the literature review shows that UA, particularly soil-less cultivation, is feasible and viable in Mexico. Modern technologies, such as hydroponics and aeroponics, enable efficient use of water and space, which is crucial in a country with arid and semi-arid zones. Climatic and geographic conditions, such as abundant solar radiation in the northern states, favor these practices. Despite challenges such as the need for initial investment and water resource management, the advantages outweigh the disadvantages. These practices can reverse the overexploitation of aquifers and soil erosion, promoting environmental, economic, and social sustainability.