The purpose of this study was to use soil physical and chemical analyses to better understand the ancient agricultural landscape around the ancient Maya cities of Rio Amarillo and Piedras Negras, two tributary sites to Copan, Honduras. Our primary objective was to determine whether a mass erosion event around 800 A.D. occurred which could have caused crop failure and famine or if stable soil conditions persisted during the collapse of these city-states. Stable carbon isotope analysis of the humin fraction of the soils showed that much of this valley was used anciently for agriculture, including hillslopes and hilltops; however, there is no evidence of mass erosion in the soil profiles. Soil horizon development and texture is consistent with stable soil conditions in this area. The demise of these city-states was likely caused by a variety of factors including warfare and political unrest, and not solely by environmental degradation as postulated in previous studies of the valley.

The objective of this study was to use soil chemical properties, particularly carbon isotopes to describe the agricultural landscape in the Blue Creek region on the Rio Bravo Escarpment in northwestern Belize. The primary question associated with this study focused on the comparative agricultural potential of the soils between the upland karst environment and the lowland coastal plains using the distribution and frequency of ancient Maya maize production. Soil physical features, such as clay concentrations throughout profiles in conjunction with soil chemical properties were used to aid in determining the level of ancient maize production. Isotopic evidence suggests that anciently, lowland soils were used for maize production more so than upland soils. In addition, profiles at Crocodile Lake indicate the potential for transport of soil δ13C signatures as a result of mass movement events.

The objective of this study was to use pedological evidence in conjunction with Geographic Information Systems, and soil physical and chemical analyses as means to better understand the agricultural landscape surrounding the ancient Maya city of Uci. Specifically, the query of this thesis is to determine whether there is an association between settlement density and soil resources, and what relationship if any there is between the ancient sacbe of Uci and its surrounding agricultural potential. Stable carbon isotope analysis of the humin fraction of the soil organic matter was conducted on several profiles from karst depressions known as rejolladas near the site center, and from a select number of sufficiently deep profiles along and surrounding the ancient sacbe, and from beneath ancient structures. A strong C isotopic signature of ancient C4 crops was found in a limited number of profiles while a majority of the profiles showed no evidence, or little to inconclusive evidence due to a mixture of C3 and C4 plants in the natural landscape. A majority of the soils surrounding Uci are shallow to extremely shallow and many profiles sampled and studied did not allow for C isotopic analysis. Isotopic evidence along with other soil chemical and physical characteristics suggests that settlement density was linked to soil resources, specifically in the case of the rejolladas proximity to the Uci site center. However, it does not appear that the construction and location of the sacbe was linked to its surrounding soil resources or agricultural potential even though ancient maize crops may have been cultivated sporadically close to the sacbe and nearby structures. The soil resources of Uci are not conducive to the production of large maize crops and the ancient Maya of this area likely utilized maize along with alternative crops, arboriculture, wild game and trade to sustain its population.