Stable isotope measurements reveal diverse agricultural management strategies in the Roman Iron Age (1–400 cal AD) southeast Baltic

Abstract This study presents a series of new radiocarbon dates and the first stable carbon and nitrogen isotope measurements of C 3 cereal grains from Roman Iron Age (1–400 AD) archaeobotanical assemblages in Lithuania, southeastern Baltic region. These data are complemented by stable isotope measurements of faunal remains to assess local environmental conditions and evaluate human impact on the landscape through agricultural practices. The δ 15 N and δ 13 C values indicate that agriculture during this period relied heavily on intensive manuring and cultivation in open, well-irrigated landscapes. The results also reveal diverse cultivation strategies across sites, with isotopic differences between rye and barley suggesting the possible use of an infield–outfield cultivation system. Radiocarbon dates indicate that these agricultural innovations may have started as early as the 1st to mid-2nd century AD with the introduction of rye, however the evidence points to a gradual and uneven adoption rather than a rapid uniform shift.