Researchers find 1,400-year-old crop field

Colorado researchers have found the first direct evidence of manioc cultivation in the Americas, the remains of a 1,400-year-old field in El Salvador that was buried by volcanic ash shortly after the crop was harvested.

Manioc, also known as cassava, produces the highest yield of food energy of any cultivated crop, and its widespread use by the Maya could help explain how they sustained high population densities, said archeologist Payson Sheets of the University of Colorado, who made the discovery in the village of Ceren.

A village of about 200 people, Ceren was buried by the eruption of a volcano in A.D. 590 that covered the village with as much as 17 feet of ash, preserving houses and their contents in remarkable detail.

Based on the height of the corn in the fields and the fact that farming tools had been put away but bedrolls had not been unrolled, researchers believe that the eruption occurred early in the evening in August. No bodies have been found.

Sheets and his colleagues discovered the evidence of manioc cultivation in June when they were excavating an underground anomaly revealed by ground-penetrating radar, the University of Colorado said Monday.

The manioc was long gone. What they found were holes left behind in the solidified ash as the manioc rotted away. They filled the holes with plaster of Paris, then chipped away the ash to reveal what had been there.

They found hand-shaped planting beds about 3 feet wide and 2 feet high. The crop apparently had just been harvested.

The idea that manioc was used by the Maya was first proposed in 1966 by archeologist Ben Bronson. That it provides six to 10 times as much food energy per acre as corn made it a feasible food source that could support a population that researchers were concluding reached hundreds of people per square kilometer.

The new discovery might help researchers develop evidence of manioc cultivation at other locations, Sheets said.