Studying ancient crop provenance: implications from d 13 C and d 15 N values of charred barley in a Middle Bronze Age silo at Ebla (NW Syria) Girolamo Fiorentino 1 * , Valentina Caracuta 1 , Grazia Casiello 2 , Francesco Longobardi 2 and Antonio Sacco 2 1 Laboratory of Archaeobotany and Palaeoecology, University of Salento, - Cultural Heritage, Via D. Birago 64, Lecce 73100 Italy 2 Department of Chemistry, University of Bari, Via Orabona 4, Bari 70126 Italy The discovery of a storeroom full of barley and other cereals (L.9512) in the proto-historic site of Ebla has provided a unique opportunity to study the centralized storage system of the early city-state from a different perspective. Epigraphic evidence available within the site reveals a complex system of taxation which included gathering grain tributes from satellite sites and redistributing semi-finished products such as flour. In this paper, we intend to explore the possibilities of a combined approach to studying the storage system, based on estimated barley grain volumes and d 13 C-d 15 N analyses. This approach is used to distinguish between grain from different harvesting sites and to identify any grain cultivated using special agricultural practices (e.g. manuring or irrigation). The basic assumption for this kind of analysis is that the growth-site conditions, natural or anthropogenic, of harvested cereals are reflected in their grain size and d 13 C-d 15 N values. Since the remains found in the storeroom were charred, the first task was to evaluate the effect of carbonization on the d 13 C-d 15 N and the size of the grains. Thus, the effect of charring was tested on modern samples of Syrian barley landraces. Once it had been ascertained that fresh grains reduced to charred remains retain their original biometric and isotopic traits, the ancient material was examined. Thirteen groups were identified, each characterized by a specific average volume and specific carbon and nitrogen values. The analysis revealed that what had first appeared to be a homogeneous concentration of grain was in fact an assemblage of barley harvested from different sites. Copyright © 2012 John Wiley & Sons, Ltd. Stable isotopes of nitrogen and carbon have been widely used in archaeology to investigate the dietary habits of ancient populations, [1,2] past environmental conditions [3] and agricultural practices. [4,5] For the latter, most of the analyses have focused on irrigation, [6] fertilization techniques and the state of soils. [7] Given that these two isotopes have rarely been studied jointly in previous analyses in archaeological issues, by combining isotopic ratio data (d 13 C and d 15 N values) and size analysis we intend to characterize growing-site conditions and/or identify agricultural practices (e.g. irrigation or manuring) which can affect isotope values in plants. Biometric analysis helps to determine the origin of plant remains: grain size is affected by edaphic conditions during growth, [8,9] and therefore grains of the same species from the same harvesting site are likely to have the same volume. [10–12] Stable isotope values help to refine this analysis by characterizing the environmental features of the harvesting site. [13,14] In addition, they can indicate additional water or nutrient inputs. [15,16] In this study, we selected 91 caryopses of barley from the archaeobotanical assemblage found in storeroom L.9512. Wheat was the main stored cereal but barley was preferred because it was expected to better reflect growth site conditions. [17,18] Since the archaeobotanical assemblage in L.9512 was made up of charred remains, the first task was to evaluate the effect of carbonization on the isotope signature and the size of the barley grains. Thus, the effect of charring was tested on modern samples of Syrian barley landraces. Once it was ascertained that fresh grains reduced to charred remains more or less retain their characteristic size and d 13 C-d 15 N values, we plotted these parameters together in order to characterize the different harvesting sites of the barley in the ancient material and to verify whether further distinctions could be made in terms of agricultural practices. RESEARCH BACKGROUND The main chemical components of cereals are primarily governed by the water and soil layer in which they grow and can to some extent be influenced by human practices such as additional water inputs and manuring. [19] Therefore, if used properly and correctly understood, stable carbon and nitrogen isotopes can provide reliable information on * Correspondence to: G. Fiorentino, Laboratory of Archaeo- botany and Palaeoecology, University of Salento, Cultural Heritage, Via D. Birago 64, Lecce 73100, Italy. E-mail: girolamo.fiorentino@unisalento.it Copyright © 2012 John Wiley & Sons, Ltd. Rapid Commun. Mass Spectrom. 2012, 26, 327–335 Research Article Received: 29 July 2011 Revised: 3 November 2011 Accepted: 7 November 2011 Published online in Wiley Online Library Rapid Commun. Mass Spectrom. 2012, 26, 327–335 (wileyonlinelibrary.com) DOI: 10.1002/rcm.5323 327