Stable isotope analysis in soil prospection reveals the type of historic land-use under contemporary temperate forests in Europe

Abstract

The determination of δ¹³C and δ¹⁵N values is a common method in archaeological isotope analysis—in studying botanical and human remains, dietary practices, and less typically soils (to understand methods of agricultural cultivation, including fertilization). Stable isotope measurements are also commonly used in ecological studies to distinguish different ecosystems and to trace diachronic processes and biogeochemical mechanisms, however, the application of this method in geochemical prospection, for determining historic land-use impact, remains unexplored. The study at hand focuses on a deserted site of a Cistercian manor, dating from the thirteenth to fifteenth centuries. Isotopic measurements of anthropogenically influenced soils have been compared to approximately 400 archaeobotanical, soil, and sediment samples collected globally. The results reveal the potential of isotope measurements in soil to study the impact of past land use as isotope measurements identify specific types of agricultural activities, distinguishing crop production or grazing. δ¹³C and δ¹⁵N ratios also likely reflect fertilization practices and—in this case—the results indicate the presence of cereal cultivation (C₃ cycle plants) and fertilization and that the site of the medieval manor was primarily used for grain production rather than animal husbandry.