Britannica Sources used in this answer

How did the Three Sisters agricultural system combine corn, beans, and squash?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Domesticated yaks carrying supplies in colorful bundles walk along a rocky mountain trail toward Everest Base Camp, with snow-covered peaks in the background in Sagarmatha National Park, Nepal. — Domestication Domesticated yaks (*Bos grunniens*) carrying supplies to an Everest base camp in Sagarmatha National Park, Khumbu region, Nepal.

The Three Sisters agricultural system, also known as milpa, is a symbiotic intercropping method where corn, beans, and squash are planted together, typically in mounds or hills. This system relies on the unique biological contributions of each plant:12

Corn: As the first to emerge, the cornstalk provides a natural trellis for the beans to climb.12
Beans: These plants fix nitrogen in the soil through nitrogen-fixing bacteria in their roots, providing essential nutrients for the other crops.12
Squash: Growing along the ground, the squash’s large, fan-shaped leaves shade the soil, which helps retain moisture and suppresses weeds.12

This sustainable agriculture practice increases biodiversity and provides food security, as the crops support one another’s growth while offering a nutritionally balanced diet of starches, proteins, and fats.1