Inherited landscapes: Ancient Maya land use and soil transformation

The ancient Maya site of Budsilhá in southern Mexico, while not a major city, was once home to a palace and noble court that was vital to the politics and economy of the era. The hilly landscape had sweeping terraces with dwellings constructed on the uplands and crops growing in the lowlands, crops that were essential to the health and economy of the region. As is the case with nearly every society on earth, its foundations lay in the soil on which buildings and homes were built and in which crops were grown. 

And that soil has a story to tell. 

For many years, unique interdisciplinary research partnerships have brought together archeologists, anthropologists, soil scientists, and ethnobotanists to work at ancient Maya sites to better understand how their inhabitants developed the land and defined their culture. By overlaying the results of archeological excavation with studies of the soil, they are able to piece together the land use of the ancient Maya. 

In a new article in the Soil Science Society of America Journal, scientists at the Universidad Nacional Autónoma de México in Mexico City, Brandeis University, and Brown University studied soil development and ancient Maya land use at the Budsilhá site. Budsilhá is in a tropical karst landscape characterized by an abundance of limestone bedrock, which produces a characteristic jagged relief of hills, sinkholes, and caves as it weathers.

“We studied the soils around Busiljá Valley and their relationship to the Maya occupation of the area,” explains Pamela García-Ramírez, a graduate student at the Universidad Nacional Autónoma de México who served as lead author on the paper. “We focused on understanding the land use and what the relationships were between soil development and cultural activities. Our goal was to understand what was happening in the countryside in these ancient Maya communities.” 

The archaeological site of Budsilhá is located in a landscape of dramatic relief—especially compared with Maya sites farther north on the Yucatán Peninsula—meaning it is defined by narrow valleys, jagged hills, and the tributary streams feeding into the Usumacinta River. The soil scientists describe how they reconstructed the environmental setting and soil mantle over which cultural development took place. 

Their major findings provide evidence that the highlands had thin, poor soils—largely classified as Rendolls—and were filled with constructed dwellings while the swampy lowlands—classified as Aquepts—were managed in a way that allowed for productive agriculture in their deeper and more developed soils. The results also point to detrimental erosion that occurred in the highlands and some surprises in the lowlands, such as the unexpected presence of gypsum in the soil. Taken together, the findings showed a soil mantle and landscape heavily impacted, often negatively, by ancient Maya civilization. 

An ancient landscape modified for agriculture 

The Budsilhá site is located in southern Mexico in the state of Chiapas near the border with Guatemala. The hilly and mountainous region is hot and humid, receiving 3,413 mm (more than 130 inches) of rainfall each year. A relatively large community with inhabitants spread out around the countryside, it was not a major metropolis and was likely interwoven culturally and economically with larger cities and kingdoms nearby, such as the powerful metropolis Piedras Negras. The research team believes it was inhabited from at least 400–900 CE. 

Charles Golden, an archeologist at Brandeis University, has worked in this region since the late 1990s and at Budsilhá since 2012. He describes an ancient time in capital cities with kings and queens living opulent lives and raising temples to the gods, punctuated by periods of violence between warring kingdoms. But much less is known about the smaller towns and villages, which likely housed the courts of noble lords and played a critical role in producing food for a rapidly expanding population. The details of how this food system was maintained are largely unknown. 

“In some ways Budsilhá is an island in a swamp,” Golden says. “The archeological site is on a rise in a seasonally inundated wetland. As a relatively large village, we know it had a palace and played an important role in this ancient world. Through remote sensing techniques like Light Detection and Ranging (LiDAR), as well as artifacts found through excavation, we’ve been able to understand some of what the area looked like and was used for.” 

Remote sensing shows a landscape clearly modified for agriculture. The hills were terraced to allow for the constructions of dwellings, which required the excavation and moving of large amounts of soil. Some of these homes would have been accompanied by small home gardens while the majority of agriculture occurred farther downhill. 

In the lowlands, there is evidence of channels being built to manage the annual inundation of the landscape in the wet season as well as transport water in the dry season. Golden says these were likely made by excavating the trenches and piling the soil up on the open fields.  

The ancient Maya commonly practiced slash-and-burn agriculture where an area of forest is burned and planted on, and over time as it becomes less fertile, is allowed to regrow. Unlike modern monoculture, ancient residents likely cultivated a mosaic of crops, including staples like corn, beans, squash, and root crops like manioc (also known as cassava) and arrowroot. They also cultivated a complex canopy and understory of trees and plants, such as cacao and vanilla, that would serve as luxury market crops.

“What we are seeing is a landscape that is drastically transformed by water and people together,” Golden says. “There is a lot more human intervention in these landscapes and the soils than we had previously thought. Through the centuries there was a lot of intensive landscape modification going on. And the partnership with Pamela and others has brought in their expertise to understand how that human intervention has changed the development of soils over the centuries.” 

"What we are seeing is a landscape that is drastically transformed by water and people together. There is a lot more human intervention in these landscapes and the soils than we had previously thought."

Most consequentially, the colonizing of this land required deforestation. Sergey Sedov, a professor of soil science at the Universidad Nacional Autónoma de México who was part of this research, has partnered with archeologists on ancient Maya sites for decades. He says that deforestation coupled with the heavy rainfall in this area leads to near immediate soil erosion. 

The group’s findings in the soil have led them to understand how the soils at sites like Budsilhá are not as natural as they may seem but have definite anthropogenic components. The results from studies of the soil profile confirm the archeologists’ understanding of ancient Maya land use and how the society changed the landscape. 

“We found evidence of the preexisting red soils in the hills that has been eroded,” Sedov explains. “Further, we found evidence that these soils were deposited in the lowlands, so [we] can trace this eroded soil material. This was difficult because the saturated environment of the lowlands transformed the redeposited soil material and erased many properties of the original soil. While not easy to recognize, we found strong evidence of some features, such as the composition of clay minerals, that tell us that these depressions contain soil eroded from the highlands.” 

One of the biggest surprises the researchers found was the presence of gypsum in the lowland soils, which is uncommon in humid tropical areas. Rather large crystals were found in the upper and medium soil horizons. In an area with so much precipitation, gypsum and other soluble salts would normally be washed from the soil, Sedov says. 

“Yet at this site it was not only present, but we could tell the crystals were formed here in this soil recently and did not come from elsewhere,” he says. “They were quite fresh. This is still a bit of a mystery to us, a very enigmatic feature of this soil. It told us once again that the soil development in this karstic environment is very different from normal soil development in humid tropics.” 

Did soil degradation contribute to the Maya’s decline?

How did the Maya feed their growing population in this environment and respond to their negative impacts on the landscape? The researchers point to their past work, which details a form of ancient precision agriculture that manages small areas of soil individually. In addition to altering the landscape by building channels to move water, the Maya also worked with what they had by, for example, planting crops with shallow roots in soils that were not deep enough to support anything else, and planting others, often tree crops, in deeper soils. While labor intensive, it was productive and fed their society. 

“What we detected in our research is that the soil mantle is dynamic,” Sedov says. “There have been large changes that occurred over the last millennia to this soil and these changes were partly related to the impact of Maya civilization. There was different soil when the Maya arrived there and different soil today because of the effects of their practices, particularly degradation and erosion of upland soils.”