In the days of the empire, Aztec agriculture was a lot more complex that growing a few stalks of maize. The remarkable farming practices of the peoples in central Mexico has been studied and admired ever since.
Prior to the Spanish conquest of Mexico, Aztec society ruled the central Mexico, built on the foundations of Mesoamerica. Aztec society was highly structured and complex, and the political emphasis was working as a larger unit with smaller parts that worked together.
Aztec farming has become most famous because of the brilliant chinampas system that Aztec farmers used. Certainly there were a number of techniques used in the Aztec empire. But with the great city of Tenochtitlan built on swampy but rich ground, the chinampas became key to the food production of the people.
Chinampas were, of course, not just used for the capitol city, but throughout the Valley of Mexico around the lake bed. As the empire grew, more sources of food were required. At times this meant conquering more land, other times it meant expanding the chinampa system.
Chinampas were floating gardens built on swamps. The process of making chinampas was a relatively simple one. First, canals were built through the marshes and swamps. Then, the mud from the canals was placed on mats, which were made from weeds and straw. Then, trees were planted at the corners. When these trees took root, they secured the chinampa firmly in place. Once the floating island was secure and useable, the Aztecs used it to plant their principal crop: corn.
They also grew various vegetables (such as avocados, beans, chili peppers, squash, and tomatoes), and sometimes-even flowers. Unfortunately, the Aztecs had no animals or machines to help them work the land. In fact, they didn't even have plows. Thus, it was even more necessary to have soft land. Luckily for the Aztecs, the chinampas were soft enough that it was possible to plant crops with nothing but pointed sticks.
One challenge all farmers face is retaining nutrients in the soil where crops are planted. Different crops deplete the soil of certain nutrients, so if a specific crop is planted in the same field year after year, it won't grow as well. This is a particular challenge in areas of Mexico where there are large populations and small areas where farming can take place easily.
To combat this, Aztec farmers planted crops together or rotated crops to help keep nutrients in the soil, and give them the opportunity to regenerate.
Maize, squash, and beans were referred to as the "Three Sisters" in Aztec agriculture. These three crops were planted together because they kept the nutrients in the soil, ensuring the crops would grow well and the people would have the food they needed.