Modern Soil Science Unearths Mayan Agriculture Secrets
November 12, 2012

Modern Soil Science Unearths Mayan Agriculture Secrets

Lee Rannals for — Your Universe Online

An analysis of maize agriculture in the soils of Guatemala's Tikal National Park has revealed some ancient Maya secrets.

Scientists wrote in Soil Science of America Journal that they uncovered evidence for major maize production in lowland areas, where erosion is less likely and agriculture was presumably more sustainable for the Maya people.

The Maya civilization reached its peak between 250 and 900 A.D., and first emerged sometime before 1000 B.C. The civilization thrived in jungle cities of tens of thousands of people, and became one of the most advanced Pre-Columbian societies in the Americas. There could have been an estimated 60,000 people living off soil sampled in the study.

The team discovered evidence of erosion in upslope soils, suggesting that farming did spread to steeper, less suitable soils over time. If Maya agriculture did cause substantial erosion, the soil loss could have undercut the Maya's ability to grow food.

Findings from the study are the latest example of how invisible artifacts in soil can inform studies of past civilization. As buildings and artwork crumble over time, "the soil chemistry is still there," according to Richard Terry, who led the team.

He said that most forest vegetation native to Tikal uses a photosynthetic pathway known as C3, while maize uses a pathway called C4. The soil organic matter derived from these pathways allows researchers to make conclusions about the types of plants the Maya people grew in the soil.

“Archaeologists are looking for stuff–for buildings and pottery and stuff that people left behind,” Charles Golden, an archeological anthropologist at Brandeis University wrote in the journal. “So most archaeologists in the past weren´t going to say, ℠well, let´s excavate here in this soil and see what the soil looks like.´ So that´s a critical change, when the concern becomes not just the stuff people leave behind, but also the soils they create, and the landscapes they create.”

By analyzing soils in different areas of Tikal, the researchers were able to map out the places where ancient maize production took place, including lowland "bajo" areas and steeper slopes.

Terry said that questions like this about past farming practices have always been of interest to archaeologists. However, the tools of modern soil science are just now enabling scientists to answer questions about how ancient people tried to sustain themselves.

"[These tools] open us up to thinking about the world in ways that we haven't before," Terry said in a statement. "We have changed the paradigm amongst the archaeologists."

Researchers used a battery-operated spectrophotometer in a field laboratory to identify spatial patterns of various chemicals on the floors. During these observations, they were able to find phosphorus, which indicates the remains of food.

They discovered significant amounts of phosphorous along the edges of floors and household patios, indicating those areas had been swept clean. They found low levels of phosphorous in sleeping and pathways, and higher levels in kitchen and dining areas.

The scientists also found phosphorous lining the edges of large, open plazas, leading to a new theory about the Maya having a marketplace.

“The thought is: Could the ancient Maya have conducted marketplace activity at the plazas?” Terry asks in the journal. He said vendors in ancient times could have sold goods in public places during the day and then packed up and cleaned in the evening.

Because of their cleaning habits at the end of the day, no tangible evidence of their activities would have been left behind for archaeologists to uncover.

“The problem for the archaeologist is that they find these plazas all over the Maya world–in fact, all over the Americas–and they appear as empty spaces,” Terry wrote in the journal. “There are no artifacts. There´s just nothing remaining. But the soil chemistry is still there.”