A study published in the journal Nature reveals that the pre-Columbian Casarabe society in the Amazon developed an agricultural engineering system, transforming seasonally flooded savannas into highly productive fields for year-round maize cultivation. The research, led by Umberto Lombardo from the Universitat Autònoma de Barcelona, detailed how the Casarabe people constructed extensive drainage canals and agricultural ponds, enabling at least two annual maize harvests and supporting the development of a growing population.
The study's conclusions were made possible through fieldwork combining techniques such as microbotanical analysis, remote sensing, and environmental archaeology. These methods allowed researchers to analyze 178 samples of phytoliths (plant microfossils) and pollen from a pond, confirming the presence of maize in the fields.
"We can document that this is the first grain-based agrarian economy in the Amazon, where until now we believed that the agriculture practiced was of polycultures in agroforestry systems and not of large-scale monocultures. Now we know that this was not the case in the Llanos de Moxos," said Lombardo, the lead researcher, according to La Vanguardia.
The Casarabe people inhabited the Llanos de Moxos region between 500 and 1400 CE. This tropical lowland savanna, characterized by intense rainy seasons and flooding as well as very dry seasons, was transformed by the Casarabe's agricultural practices, according to El Periódico.
As described by Ara, one of the key features of their system was a dual water management approach based on extensive drainage canals and agricultural ponds. This enabled the Casarabe people to drain excess water from flooded fields during the rainy season and retain water during the dry season, facilitating year-round maize cultivation.
"The data show the absence of other types of crops," said Lombardo, indicating that maize was likely the staple crop of the Casarabe culture, according to Science Daily. This intensive agricultural strategy suggests that maize was not only cultivated but played a crucial role in their diet.
The findings contradict previous theories that dismissed the possibility of intensive monoculture agriculture in the Amazon region. Until now, it was thought that agriculture in the Amazon was primarily based on polycultures in agroforestry systems.
Using satellite images and ground surveys of Casarabe territory, Lombardo's team identified clusters of human-made ponds in two savanna regions. Canals dug into the ground, mapped using a drone-mounted remote sensing technique called light detection and ranging (Lidar), connected many ponds. Soil samples from the edges of drainage canals and ponds contained microscopic mineral formations called phytoliths, characteristic of maize.
The Casarabe people preserved nearby forests for other purposes, such as obtaining firewood and medicinal plants, while implementing practices that maximized the efficient use of water and soil in the seasonally flooded savannas. Their agricultural model did not rely on traditional slash-and-burn techniques used to create fertile fields.
"This innovative piece of engineering allowed for the transformation of a challenging environment into a productive system that ensured food stability and supported the development of a growing population," asserted Lombardo.
The Casarabe society controlled approximately 4,500 square kilometers of the Llanos de Moxos.
This article was written in collaboration with generative AI company Alchemiq