Isotopic evidence for changes in cereal production strategies in Iron Age and Roman Britain

Following the Roman conquest, agricultural production in Britain faced increasing demand from large urban and military populations. While it has long been thought that this necessitated an increase in agricultural production, direct archaeological evidence for changes in cultivation practices has been scarce. Using a model that conceptualises cereal farming strategies in terms of intensive or extensive practices, this paper is the first study to address this question using carbon and nitrogen stable isotope data of crop remains. We report δ15N and δ13C values from 41 samples of spelt, emmer and barley from Bronze Age, Iron Age and Roman Stanwick (Northants., UK), in order to assess the intensiveness of arable farming and investigate shifts in cultivation practices in prehistoric and Roman Britain. The results demonstrate a decline in δ15N in the Roman period, suggesting that farming practices moved to lower levels of manuring and, by implication, became more extensive. δ13C values are comparable in all periods, supporting the suggestion that changes observed in human stable isotope data between the Iron Age and Roman period are best explained by dietary change rather than a shift towards higher δ13C values in plants at the base of the food chain.