Agricultural yields in Northwest Yucatán are constrained by climate, thin soils, and low fertility. Despite this, the ancient Maya city of Chunchucmil Yucatán, Mexico, boasted an immense, dense, and wealthy population during the Middle Classic period (ca A.D. 400-700). Soil physical and chemical properties were explored to determine how the ancient Maya of Chunchucmil fed themselves. Soil profiles were collected from various locations within ancient Chunchucmil's suspected sustaining area. The physical and chemical properties, carbon isotopes, black carbon, and coprostanols of soil profiles sampled were compared to ancient rural settlement and remotely sensed images, such as AIRSAR (airborne synthetic aperture radar). Our objectives were to geographically determine the areas of agricultural importance and determine whether evidence of ancient agricultural intensification could be observed in the surrounding soil resources of Chunchucmil. Indigenous Maya of the area identify three major soil classes, boxlu'um, saklu'um, and kancab. The ancient Maya likely preferred kancab because it provided some security with higher soil moisture, greater soil depth, and improved nutrient availability. The land use capability is severely limited in the swamp/estuary and tzekel. The lack of rural settlement within these zones suggests that they were not used for cultivation in ancient times; however, the wood resources likely provided Chunchucmil with vital raw materials. The carbon isotopic signature of ancient C4 crops was not detected suggesting that either maize was not extensively produced or that the mix of native C3 and C4 plants in the savanna hid the signature. There were no soil chemical or biomarker evidences of ancient agricultural intensification, suggesting that ancient agriculture was mainly based on shifting cultivation at Chunchucmil. Concentrations of black carbon, calcium, phosphorus, potassium (Olsen Method), magnesium, and organic carbon within urban and rural settlements were enhanced by incidental human activities. We determined that the land requirement would have been extensive to sustain the population of Chunchucmil during the Middle Classic based on traditional agricultural methods. The ancient Maya of Chunchucmil likely traded marine and estuary products from the Gulf coast and other high value trade items for agricultural products from the nearby Puuc Hills.



College and Department

Life Sciences; Plant and Wildlife Sciences



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ancient agriculture, soil resources, carbon isotopes, back carbon, GIS, soil fertility, biomarker, rural settlement, soil taxonomy, ethnographic soil classification