How did the ancient Aztecs sustain high crop yield with essentially “organic farming” (without pesticides)?

Were insects a concern?

What We Discovered

The ancient Aztecs settled in swampy, inhospitable lands in Mesoamerica and established Tenochtitlan as their capital in 1345 AD. This area was the center of the Aztec Empire. Tenochtitlan stood on an island in an embayment of Lake Texcoco. The Aztecs’ survival, and their eventual rise as a dominant empire, depended upon an ingenious solution to the use of limited land. To create additional farming space, the ancient Aztecs developed “floating gardens” of mud and silt built around anchored trees. The floating gardens were called chinampas. These gardens were patches of land built in layers of mud and silt, anchored in the fresh water of Lake Texcoco. The Aztecs planted maize (corn) and other crops on the floating gardens to feed their increasing population. Wild onions, tomatoes (“xictomatl”), a turnip root (“jicama”), sweet potatoes (“camotli”), green tomatoes (“tomatl”) and several varieties of mushrooms and chilies were cultivated by the Aztecs.

By 1519, the combination of chinampa agriculture, terrace farming and floodwater irrigation supported the densest population to ever inhabit the area. Archaeological evidence substantiates the extensive use of chinampas, estimating that 22,230 acres of productive soil were utilized. The yields from this unique farming system per unit of tilled land are thought to have been extremely high. It is estimated that chinampa farming in the Xochimilco-Chalco Basin probably nourished some 100,000 people.

The writings attributed to members of the Cortez army, which conquered the Aztecs in 1521 A.D., include references to red plants on the floating gardens. Dr. Paul Gepts, of the University of California-Davis, mentions the Amaranthus as a tribute crop appearing in the Codex Mendoza. We have discovered that plants by the name of Amaranthus spp, produce a red cluster of seed grains that resemble a bright flame. Today, Amaranthus grows wild in the ancient lands surrounding Tenochtitlan.

Next, we contacted Christina Mapes at the National University of Mexico, the Instituto de Biologia. She referred us to an interesting book written by M.A. Altiere, Biodiversity and Pest Management in Agroecosystems, 1994. On pages 49-51 and 60 there are some examples of different species of Amaranthus that repel insects. In countries including Mexico, Nepal, Peru, and India, amaranth grain is a traditional food either eaten as a cereal or mixed with other flours. Many species of Amaranthus are found in wetlands or semi-desert life zones.

The swampy lands of the ancient Aztecs could have supported Amaranthus and explain the red flowers described in the Codex Mendoza.

Further research led us to a report by G. Kelly O’Brien and Martin L. Price which stated, “Amaranth has been cultivated for more than 8,000 years, dating back at least to the Mayan civilization of South and Central America. It was a staple of the Aztecs and was incorporated into their religious ceremonies. In 1561 the conquistadors prohibited the growing of amaranth.” G.A. Iturbide from the Instituto Politecnico Nacional, Durango, Mexico and M Gispert, Science Raculty, UNAM, Mexico City writing in Neglected Crops: 1492 from a Different Perspective, 1994 indicate that the common Spanish name for Amaranthus cuuentes and Amaranthus hypochondriacus was “huautli” and the English name was “prince’s feather.” O’Brien and Price offered us an important part of the puzzle.

“Archeological finds in Tehuacan in Pueblo, Mexico show that they were already cultivated over 6,000 years ago. They reached their maximum use when grown by the Aztecs in the valley of Anahuac; their cultivation began to fall off in the colonial period. Huautli was so firmly established in the food, religion and agricultural practices of pre-Cortez Mexico that even a bird which sought its seeds at harvest time was named ‘uauhtotl’ which comes from ‘huautli’ and the word for bird, tototl. A drink (atole) which was prepared with water and huautli or prince’s feather flour was called ‘uauhatolli’ and flour dough filled with its leaf was called ‘huauquillamalmaliztli.’ In the Aztec religion, months were designated in which dough called tzoalli was prepared with the flour of the Amaranthus seeds and honey of maguey. Depending on the monthly festivity involved, the dough was used to mold different figures ranging from small pyramids to images of mountain deities. These idols were handed around in pieces among those present and were thus eaten. In the eyes of the colonizers (Spanish) ceremonies of this type seemed similar to the Christian Eucharist, hence its cultivation was persecuted and its consumption prohibited. The two direct allusions to the prohibition of its cultivation were made by Fray Bernardino de Sahagun in 1570 and by Ruiz de Alarcon in 1626.”

Certainly, maize was grown on the floating gardens of the chinampas, and, we are now certain, Amaranthus. Scientists have discovered that it is a rich source of vitamin C, iron, carotene, calcium, folic acid and protein. On a dry weight basis, the content of protein in leaves is approximately 30%.

Is There a Connection Between Amaranthus and Insects?

Perhaps, Amaranthus spp, were planted as an insect deterrent as well as a rich food source?

We contacted David Brenner, a researcher who takes part in the U.S. National Plant Germplasm System. Dr. Brenner is the curator of Amaranthus, Celosia, Chenopodium, Coronilla, Dalea, Galega, Melilotus, Perilla, and Spinacia at the Plant Introduction Station, Iowa State University. In an e-mail dated Dec. 14, 1998, Dr. Brenner stated, “I have seen Amaranths grown on the edge of maize fields in Pakistan, and wondered why. I have heard that amaranths are planted around maize in China to repel monkeys. I can believe that amaranth would be more drought-tolerant than maize where this is done on terraced mountain fields. I have also heard a bird control reason. However, I do not think that I understand (it).”

Maybe insects were harvested?

Christina Mapes at the National University of Mexico, the Instituto de Biologia, referred us to a book by R.S. Gliessman, Agroecology: Ecological Processes in Sustain Agriculture, Ann Arbor Press, Inc. Although we were not able to obtain the book, we later learned from Mapes that there is a long history of the people of Mexico using insects as food and medicine. Thomas H. Fredericksen’s writings on Aztec Medicine indicate that a potion was made from insects from the Jatropha currea and Spondias trees. “The carefully selected and harvested insects were boiled in water and during the boiling process, a waxy like film would come to the surface of the water which was then collected.” This waxy film was used to cure rashes and treat ulcers and infections.

A member of our Insecta Inspecta World team went to Mexico City to obtain documents written in Spanish regarding chinampas farming. Inspecta Diaz translated the documents when she returned. What we discovered offered new evidence that deserved consideration.

“The Aztecs, during their voyage to find the chosen land, had to eat whatever they found on the way in order to survive. Since insects are the most abundant animal group in the world, and make up eighty percent of the animal kingdom and, on occasion, form great masses of live subjects, they couldn’t take them for granted. In addition, generally they are easy to locate, collect, preserve, and keep. Insects are found in all habitats: fields, mountains, desert, trees, creeks, rivers, lakes, and in aquatic places. Therefore, the Aztecs found them everywhere they went, and without doubt, they became accustomed to consuming them. Insects constructed part of their ordinary diet, not only when they established in Tenochtitlan, but in their long journey to get there. In addition, when the Aztecs got there and established at the top of a lake called Acocolco, their life was very poor. It is said they only maintained themselves by eating fish and all kinds of insects. However, this necessity was helpful so that they could explore the lake intensely and would come to know all that could be used as food, most of what was of a high content of nutrition.”

Translated from:

El Consumo de Insectos Entre Los Aztecas, page 90

Julieta Ramos-Elorduy and Jose Manuel Pino Moreno, Instituto de Biologia, UNAM

Since corn (maize) was the principal crop of the Aztec, it is reasonable to believe that it would attract the typical insects that attack forage crops. Chewing insects like the armyworm and the corn earworm might be a problem. Perhaps insects feeding within or upon stem roots like the corn borer, cutworms, seed-corn maggot or corn rootworms would be a nuisance. Maybe sucking insects like the corn leaf aphid might cause destruction. Or maybe, they were harvested rather than avoided. In West Africa, termites are collected and eaten as a rich source of protein during drought years. Today, a round, fat caterpillar (family: Megathymidae) appears at the bottom of a kind of Mexican liquor called Mescale. The worm is considered a delicacy to the lucky recipient. Maybe insects were just considered part of the meal!