The research shows that the ancient milpa “three sisters” polyculture of maize, beans, and squash is a highly efficient, sustainable farming system that boosts yields, enriches soil, supports biodiversity, and offers a model for future climate-resilient agriculture.
Imagine a farming system so clever that it naturally fertilizes itself, controls pests, improves soil health, and provides a complete diet—all without chemical inputs. Sounds Perfect? Actually, it’s ancient! This is the milpa polyculture, often called the “three sisters” system: maize 🌽, beans 🫘, and squash 🎃 grown together in harmony.
A recent research paper dives deep into this time-tested agricultural strategy, showing how it remains a model for sustainable agriculture in today’s world of climate change and resource scarcity. Let’s unpack what scientists found, why the three sisters work so well together, and how this system can guide the farms of tomorrow.
The word milpa comes from the Nahuatl language, meaning “cultivated field.” In practice, it refers to a traditional Mesoamerican system where maize, beans, and squash grow side by side.
Together, they form a self-sustaining agro-ecosystem. This system has been cultivated for thousands of years, from Mexico to Central and South America, and is considered one of humanity’s greatest agricultural achievements.
Beyond farming efficiency, the milpa system also ensures a balanced diet:
🌽 Maize provides carbohydrates and energy.
🫘 Beans add protein and essential amino acids missing in maize.
🎃 Squash offers vitamins, fiber, and healthy fats.
Together, they create a complete nutritional package—an ancient “superfood combo” designed by Indigenous farming wisdom.
One key finding of the research is that milpa polyculture is more efficient than monoculture. Scientists use a measure called the Land Equivalent Ratio (LER) to compare systems.
In other words: more food, less land, and greater biodiversity!
The benefits of milpa go far beyond food:
🐝 Pollinator diversity – The mix of flowers attracts bees and other pollinators.
🐞 Natural pest control – Predatory insects thrive, reducing the need for pesticides.
🐓 Food web support – Domestic animals and wildlife also benefit from the system.
🌳 Cultural heritage – In Mexico and Central America, milpa farming is tied to rituals, festivals, and community identity.
This makes milpa not just a farming method, but a biocultural system that sustains both people and ecosystems.
Of course, the milpa system isn’t perfect. The research points out some limitations:
⏳ Labor-intensive – Traditional milpa requires much more manual work compared to mechanized monocultures.
🚜 Hard to mechanize – Since maize, beans, and squash grow at different rates and have different harvest times, modern machinery struggles with efficiency.
🔬 Scientific gap – There’s still limited research on optimizing this system with modern agricultural science.
But these challenges are also opportunities—mechanization, breeding, and microbiome research could unlock the next level of sustainable intercropping.
The researchers highlight several exciting directions for the future of sustainable agriculture with milpa:
Soil microbes in milpa help with nitrogen fixation and phosphorus availability, boosting plant growth and resilience. Recent studies found unique fungi and bacteria living in maize roots that may reduce fertilizer needs.
Farmers and scientists can collaborate to develop new landraces of maize, beans, and squash that perform even better together. Genomics and “community breeding” could make milpa more adaptable to climate change.
Programs like Mexico’s Sembrando Vida (Sowing Life) already encourage agricultural diversification. Recognizing and supporting milpa systems in national agricultural policy can ensure they thrive.
While deeply rooted in Mesoamerica, similar intercrop strategies can be adapted globally to promote food security, reduce chemical use, and conserve biodiversity.
The milpa—or three sisters—is more than a relic of the past. It’s a living example of sustainable agriculture that integrates food production, biodiversity, culture, and resilience.
By saving land, reducing chemical inputs, and offering a complete diet, the milpa shows us how agriculture can work with nature instead of against it.
As modern farming faces the pressures of climate change, resource scarcity, and population growth, perhaps the answers lie not just in high-tech solutions, but also in the ancient wisdom of the three sisters 🌽🫘🎃.
🌱 Polyculture - Growing multiple crops together in the same field. Unlike monoculture (just one crop), polyculture mimics nature and creates healthier, more resilient farming systems.
🌾 Milpa - A traditional Mesoamerican farming system where maize, beans, and squash (the “three sisters”) grow together. It’s both an agro-ecosystem and a cultural practice.
🌽🫘 🎃 Three Sisters - A nickname for the milpa trio—maize, beans, and squash—because they support each other like siblings: maize gives structure, beans enrich soil, squash protects the ground.
📊 Land Equivalent Ratio (LER) - A way to measure how efficient intercropping is compared to monoculture.
🧬 Domestication - The long process where humans select and adapt wild plants into crops with traits we like—bigger seeds, tastier fruits, better yields.
🌍 Agro-ecosystem - A farm seen as an ecosystem—including crops, soil, water, animals, and even microbes—all interacting together under human management.
🌿 Agrobiodiversity - The variety of plants, animals, and microbes used in farming. More diversity = stronger, more resilient food systems.
🦠 Microbiome - The community of microorganisms (bacteria, fungi, etc.) living in soil and around plant roots, helping with nutrient cycling and plant health.
🔄 Intercropping - A farming practice where two or more crops are planted at the same time in the same space, often in rows, strips, or mixed patterns. Milpa is one example.
Source: Mota-Cruz, C.; Casas, A.; Ortega-Paczka, R.; Perales, H.; Vega-Peña, E.; Bye, R. Milpa, a Long-Standing Polyculture for Sustainable Agriculture. Agriculture 2025, 15, 1737. https://doi.org/10.3390/agriculture15161737
From: Universidad Nacional Autónoma de México; Universidad Autónoma Chapingo; El Colegio de la Frontera Sur, Unidad San Cristóbal de las Casas.
