A University of Colorado at Boulder team has uncovered an ancient and previously unknown Maya agricultural system -- a large manioc field intensively cultivated as a staple crop that was buried and exquisitely preserved under a blanket of ash by a volcanic eruption in present-day El Salvador 1,400 years ago.

Evidence shows the manioc field -- at least one-third the size of a football field -- was harvested just days before the eruption of the Loma Caldera volcano near San Salvador in roughly A.D. 600, said CU-Boulder anthropology Professor Payson Sheets, who is directing excavations at the ancient village of Ceren. The cultivated field of manioc was discovered adjacent to Ceren, which was buried under 17 feet of ash and is considered the best preserved ancient farming village in all of Latin America.

The ancient planting beds of the carbohydrate-rich tuber are the first and only evidence of an intensive manioc cultivation system at any New World archaeology site, said Sheets. While two isolated portions of the manioc field were discovered in 2007 following radar work and limited excavation, 18 large test pits dug in spring 2009 -- each measuring about 10 feet by 10 feet -- allowed the archaeologists to estimate the size of the field and assess the related agricultural activity that went on there.