RESUMENLa milpa es un tradicional policultivo Mesoamericano que incluye maíz (Zea mays L.), calabaza (Cucurbita spp.) y frijol (Phaseolus vulgaris L.). Se caracteriza por una sinergia entre estos tres cultivos que favorece su rendimiento en conjunto y genera resiliencia ante perturbaciones externas. No obstante, retos actuales ambientales y socio-económicos disminuyen el atractivo de la milpa para los productores por lo que es necesario innovar este sistema de producción sin perder su principal fortaleza, la agrobiodiversidad. En un experimento implementado en 2015 en Piedras Blancas, Estado de México, se compararon todas las posibles combinaciones de policultivos de maíz, calabaza y frijol con los monocultivos de cada una de estas plantas. Todo el manejo fue orgánico y la nutrición se basaba en estiércol compostado de bovino. De todos los tratamientos investigados, la asociación de maíz y frijol demostró la mayor producción total, donde el maíz rindió 7.9 Mg ha -1 y el frijol 1.9 Mg ha -1 . En este policultivo, cada planta de maíz produjo 68.3 g, 1.2 veces superior al rendimiento por planta en monocultivo; y cada planta de frijol 27.5 g, lo que corresponde a su rendimiento en el monocultivo. Todas las demás combinaciones de cultivos (maíz-calabaza, frijolcalabaza y maíz-frijol-calabaza) superaron también los respectivos monocultivos en cuanto a su rendimiento total. Con respecto a la calabaza se destacó que las diversas asociaciones incrementaron su rendimiento por planta, pero disminuyeron la producción por planta de maíz y frijol asociados con la calabaza. Se conf irmó la sobrecosecha de maíz y frijol asociados comparado con los respectivos monocultivos, lo que subraya el potencial productivo de los sistemas de producción diversif icados. Palabras clave: agrobiodiversidad, agricultura tradicional, Estado de México, sobrecosecha. SUMMARYThe milpa is a traditional Mesoamerican production system based on polycropping corn (Zea mays L.), squash (Cucurbita spp.), and bean (Phaseolus vulgaris L.). Milpa is characterized by synergetic interactions between these plants that favor the total output of this arrangement and increase resilience to perturbations of the entire agroecosystem. Still, current environmental and socio-economic threats decrease the milpa's attractiveness for farmers. Therefore, innovations of milpa are necessary but should not affect its principal strength: its agrobiodiversity. In Piedras Blancas, central Mexico, in 2015, an experiment was carried out to compare all possible combinations of maize, squash, and bean polyculture. Crop management was based on the principles of organic farming and fertilization was provided using manure compost. The combination of maize and beans achieved higher total production, in which maize yielded 7.9 Mg ha -1 and beans 1.9 Mg ha -1 . In this maize-bean polyculture, each maize plant produced 68.3 g, 1.2 times higher than the yield per plant in monoculture and each bean plant yielded 27.5 g, which was equal to its performance in monocropping. All other combinatio...

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Today, agroecology is more than a science; it is a movement that advocates for a sustainable redesign of the global food system. Some of its acknowledged protagonists plead for a redesign based on the support of and for small-scale farming because small farms are considered more sustainable than large farms. The present review explores the arguments that leading agroecologists use for justifying their preference for small (frequently peasant) farms. In this review, small farms are defined as possessing a mean agricultural area of maximum two hectares, being family-owned, emphasizing outdoor production, and annually producing at least two different crops or livestock. Peasant farms are defined as subsistent small farms in developing countries. The review includes an overview of the current state of small farms and their most severe challenges. Agroecological publications of the last thirty years were scanned for arguments that sustain the hypothesis that small farms are more sustainable. It was found that there are no studies that directly compare the sustainability of farms based on their size. Instead, most studies cited to confirm the sustainability of small farms compare farms that differ in terms of both, size and farm management. Hence, it is likely that the reason for the advanced sustainability of small farms is their management, not their size. The assertion that small farms are a priori more sustainable than large ones is not supportable. Misleading use of the term "small farms" may impede the efforts of agroecology to stimulate sustainable food production.

ADDITIONAL INDEX WORDS. Mexico, raised fields, urban horticulture SUMMARY. Urban horticulture is not as new as many people think. Throughout history, different techniques have been used to ensure sustainable urban agricultural production. A good example of this is the chinampa system, which was developed during the time of the Aztecs in the region of Lake Xochimilco, south of Mexico City. A chinampa is a raised field on a small artificial island on a freshwater lake surrounded by canals and ditches. Farmers use local vegetation and mud to construct chinampas. Fences made of a native willow [bonpland willow (Salix bonplandiana)] protect the chinampa from wind, pests, and erosion. The dominating crops are vegetables and ornamentals. The canal water that rises through capillarity to the crops reduces the need for additional irrigation. A considerable portion of the fertility in the soils is system-immanent and generated in the aquatic components of the chinampa. Complex rotations and associations allow up to seven harvests per year. Chinampas also provide ecosystem services, particularly greenhouse gas sequestration and biodiversity diversification, and they offer high recreational potential. Recently, research and community initiatives have been performed to try to recover the productive potential of chinampas and align this sustainable system with the needs of the 21st century. In other parts of the world, some with a history of raised field agriculture, similar efforts are being made. The chinampa model could help supply food and ecosystem services in large cities on or near swamplands, large rivers, or lakes.

The mitigation measures (e.g., lockdown policies) in response to the COVID-19 pandemic impacted food systems in unprecedented ways, in both scope and immediacy. Food retail, for example, changed fundamentally in the United States, as access to nutritious food became limited, supply chain shortages were common, and mandatory public health measures led to behavior changes among customers and employees. In the present case study, we hypothesized that these changes led to food purchasing shifts of grocery store consumers. Such shifts are seen as an outcome of both endogenous factors at the individual level and exogenous factors at the government/policy level. Our case study sought to better understand how the pandemic and associated regulations shaped consumer food choices during the “hard” lockdown period in Montana during 2020. We selected 112 food products based on the highest sales in a Gallatin County, Montana, grocery store. They were analyzed by predefined food groups aligned to the Dietary Guidelines for Americans 2020. All purchases were processed for each selected food item during March and April 2019 (before the pandemic) and March and April 2020 (during the lockdown in Montana). To further describe the pandemic experiences qualitatively, we conducted semi-structured interviews with managers and employees from two stores in Gallatin County. Overall, we found that consumers increased purchases in most food groups during the pandemic, including nutrient-dense and energy-dense products, most outstandingly for starchy vegetables, legumes, and convenience food. Products with long shelf-life and that required preparation at home were preferred. Endogenous causes, specifically panic and rushing, were likely stronger drivers of consumer behavior and food choices than regulations. Nonetheless, lockdown policies impacted consumer food purchases. We present a series of policy and practice recommendations based on our findings and the emerging literature on this topic.

Chaya (Cnidoscolus aconitifolius ssp. aconitifolius Breckon) is a fastgrowing, semi-perennial, and semi-woody Mesoamerican euphorbiaceous. It is used as a leafy green vegetable and prevailingly cropped in tropical savanna climate. However, cropping of chaya is possible in both dryer and more humid climates. Although the crop has its origin in the Maya region of Southeast Mexico, Guatemala, and Belize, chaya is popular throughout Mesoamerica. Due to its high nutritional value, cooked chaya leaves are an essential ingredient of the diet of Maya communities, especially in Southeast Mexico. Chaya is also used as an ornamental plant, for forage, and in traditional Maya medicine, where it is used to cure a wide range of diseases such as diabetes, kidney problems, arteriosclerosis, gallstones, and high cholesterol. Chaya can be called a semi-domesticated plant: Apart from wild chaya, there are four chaya varieties, whose grade of domestication varies from cropped almost wild phenotypes to entirely domesticated: 'Chayamansa,' 'Redonda,' 'Estrella,' and 'Picuda.'

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The initial months of the COVID-19 pandemic revealed unique vulnerabilities of the global food system with notable societal consequences, calling for the need to implement resilience strategies to support food security for all. The objective of this study was to elicit perceptions, experiences, and responses of producers of diversified farms in the Northern Great Plains of the United States to the early stage of the COVID-19 pandemic toward identifying factors for strengthening the resilience of agricultural production for supporting livelihoods and food security. Between May and August 2020, a cross-sectional online survey was administered to the emerging community of diversified farm managers in two rural U.S. states, Montana and South Dakota (n = 53), where monocropping and extensive livestock production are prevalent. About two-thirds of surveyed producers (68%) reported that they did not change their farming practices in response to the pandemic up until the survey period in Summer 2020. Almost three-quarters of producers (73%) indicated that access to commodities, farm inputs, and farm labor was not a concern for them during the early stage of the pandemic. Most surveyed producers (88%) were not concerned about their household food security and expressed confidence regarding a long-term increase in the demand for local food. However, almost half of surveyed producers (47%) reported that their anxiety increased because of the pandemic. Findings further highlight that small farms implemented a greater number of practices for enhancing ecological self-regulation while depending strongly on off-farm income compared to larger farms that were economically more autonomous. This study points to the promise of farm system diversification in strengthening the resilience of agricultural systems. We conclude by outlining pathways for increasing diversity on farms toward supporting food security during extreme food system shocks.