Stable carbon isotope analyses of the humin fraction of the soil organic matter were conducted on more than 160 soil profiles from Tikal, Guatemala. The profiles were collected from near areas associated with the earthworks of Tikal; an ancient ditch and parapet construction hypothesized to have formed ancient boundaries of the polity. In addition to the isotope analyses, the physical and chemical characteristics of the horizons were determined. Maize, a C4 plant, formed an integral part of the ancient Maya diet and is the only known C4 plant cultivated by the Maya. Prior to and subsequent to the ancient Maya occupation of Tikal, the landscape was dominated by C3 forest vegetation. Over the centuries C4 plant biomass including rhizodeposition decomposed to form soil organic matter that contains a distinct C4 signature reflecting the vegetation history of the area. Forested areas anciently cleared for agriculture were identified through interpretation of significant isotopic shifts that signaled past vegetation changes. Buried horizons were encountered in the upland depressions and bajo wetlands. The aggraded soil deposits were likely the result of increased human activity related to settlement and agriculture. The buried horizons and the overlying sediments exhibited stable carbon isotope shifts associated with forest clearance and maize agriculture. Geospatial analysis of the stable carbon isotope ratios indicated that ancient Maya agriculture was focused on deeper footslope and toeslope soils in both bajos and upland depressions. Some evidence of infield agriculture or food processing was also encountered in connection with ancient settlement at upland locations. The soil data provide insight into ancient land use and sustainability that could potentially contribute to subsistence and population reconstruction models.



College and Department

Life Sciences; Plant and Wildlife Sciences



Date Submitted


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Tikal, stable carbon isotope, ancient agriculture, soil, earthworks, maize, bajo, Maya, soil organic matter