Ancient soil resources of the Usumacinta River Region, Guatemala

In this study we present the results of a combination of methods used to identify possible agricultural activity of the ancient Maya in the Usumacinta River Basin in Guatemala. These methods included stable carbon isotope analysis of bulk soil organic matter, soil profile investigations and a spatial model of gentle slopes and well-drained soils to identify favorable agricultural conditions. Stable carbon isotope analysis of bulk soil organic matter in particular offers potentially direct evidence of agricultural activity. The δ13C results suggest that there is a strong signature of C4 plants, such as maize and tropical grasses, throughout the study area. Further, the current soil conditions and extent of relatively gently sloped areas are favorable to agriculture. Overall, the results are supportive of the hypothesis that the area, located between the polities of Piedras Negras and Yaxchilán, was agriculturally important to surrounding areas.