Pre-Columbian earthworks that channeled water and enriched soils. The Paresi still farm these modified landscapes. Ancient engineering that modern agronomists are studying for sustainable agriculture techniques.
A landscape engineered for agriculture
In the Mato Grosso region of Brazil, straddling the Amazon rainforest and Cerrado savanna, Pre-Columbian people engineered vast agricultural landscapes. These are cleared fields but complex systems of earthworks, including raised fields and terraces, designed to manage water and, most remarkably, to create exceptionally fertile soil. This modified ground is a type of anthropogenic, or human-made, soil known locally as Terra Preta do Índio ("Indian Black Earth"). The Paresi people, who have inhabited this region for centuries, continue to use and manage these ancient farming systems.
The creation of these fertile zones was a long-term process, with some sites showing evidence of soil management beginning as early as 450 BCE. Generations of inhabitants systematically added a mixture of charcoal, animal bones, pottery shards, compost, and manure to the naturally nutrient-poor soil. The charcoal, produced through low-temperature pyrolysis (a process now called biochar), is the main component. Its porous structure prevents nutrients from leaching away during heavy rains, holds water, and provides a habitat for beneficial microorganisms. This process created soils that are meters deep in some places and contain up to 18 times more carbon than surrounding, unmodified soils.
Sustainable lessons from the past
The Paresi agricultural system is a form of landscape domestication. Enriching the soil in specific plots, the earthworks altered the local hydrology. Raised fields, which can be several meters wide and hundreds of meters long, lifted crops above the seasonal floodwaters of the savanna. This technique allowed for permanent or semi-permanent agriculture in areas otherwise only seasonally useful. The construction of these fields, along with associated canals and ponds, shows an understanding of water management under varying drainage conditions.
Modern agronomists and soil scientists are studying these ancient systems for insights into sustainable agriculture. The stability of the biochar means the carbon it contains is sequestered for hundreds or thousands of years, making it a powerful carbon sink. Experiments adding Terra Preta to depleted soils have shown dramatic results, with the dry mass of some crops increasing by over 8 times. The Paresi people's continued use of these lands is an example of ethnoarchaeology, where contemporary practices inform the understanding of ancient technologies. While the Paresi now also engage in modern large-scale agriculture, growing crops like soy and corn on parts of their land, their ancestral methods are a model for farming in tropical ecosystems without relying on synthetic fertilizers.
💡Fun Facts
Some patches of *Terra Preta* created by pre-Columbian societies are over 300 acres in size.
This human-made soil is so stable it is reported to regenerate itself at a rate of about 1 centimeter per year.
A related, lighter-colored soil called *Terra Mulata* ("Mulatto Earth") is often found surrounding the black earth sites and is believed to be the location of the agricultural fields themselves, while the darker soil marks the settlements.
In addition to staple crops like manioc and maize, ancient Amazonians cultivated a variety of palms, squashes, and fruits in these managed landscapes.
These sites are located on Indigenous lands (Terras Indígenas) and are not open to the public for casual tourism.
Admission
Access is strictly controlled and requires formal permission from both the Brazilian National Indian Foundation (FUNAI) and the relevant Paresi indigenous authorities.
Accessibility
The terrain is remote and typically accessed by unpaved roads through the Cerrado savanna, likely requiring a 4x4 vehicle and a local guide.
The Paresi Agricultural TerracesMato Grosso, Brazil