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ORIGINAL RESEARCH article

Front. Environ. Archaeol.
Sec. Archaeological Isotope Analysis
Volume 3 - 2024 | doi: 10.3389/fearc.2024.1465082
This article is part of the Research Topic Stable Isotope Analysis of Archaeobotanical Remains View all 6 articles

The effect of seaweed fertilisation on sulfur isotope ratios (δ³⁴S) and grain size in barley: Implications for agronomy and archaeological research

Provisionally accepted
Magdalena Blanz Magdalena Blanz 1,2,3*Darren R. Gröcke Darren R. Gröcke 4*Peter Martin Peter Martin 5Mike Church Mike Church 6
  • 1 Austrian Academy of Sciences (OeAW), Vienna, Vienna, Austria
  • 2 University of Vienna, Vienna, Austria
  • 3 Human Evolution and Archaeological Sciences (HEAS), Vienna, Austria
  • 4 Department of Earth Sciences, Faculty of Science, Durham University, Durham, England, United Kingdom
  • 5 Agronomy and Agriculture Institute, UHI Orkney, Kirkwall, United Kingdom
  • 6 Department of Archaeology, Durham University, Durham, England, United Kingdom

The final, formatted version of the article will be published soon.

    Stable sulfur isotope ratios (δ³⁴S) in bone collagen are often employed to study the consumption of marine and freshwater fish, wetland grazing, marine foraging patterns, and the possible geographic origins of food sources. However, a recent small-scale crop experiment showed that biofertilisation with seaweed can elevate δ³⁴S in Celtic beans by ca. 10 ‰. Consumption of this food could erroneously suggest a marine diet and therefore has important implications for the reconstruction of past diets and dietary origins. However, limited research has so far been undertaken on cereals. To address this issue, a large-scale field trial was undertaken on the Orkney Islands, whereby bere barley (a Scottish landrace, Hordeum vulgare L.) was biofertilised with seaweed at different dosages (25 t/ha, 50 t/ha), a mineral NPK fertiliser, and left unfertilised as a control. The total barley biomass yield was higher and barley grains were enlarged following all fertilisation treatments compared to the control barley. Barley grain and straw from seaweed fertilised crops had more elevated δ³⁴S values by around 2-3 ‰ compared to unfertilised plants, while the NPK-fertilised grains and plants had δ³⁴S values 1 ‰ lower. These results confirm previous hypotheses that seaweed fertilisation can elevate cereal δ³⁴S values. The comparatively small δ³⁴S difference between control and seaweed fertilised crops in this field trial is likely due to background elevated δ³⁴S values in the soil (+12.7 ‰), which in turn may be due to long-term exposure to oceanic-influenced rain and sea spray and/or possible historical application of seaweed, or the underlying bedrock composition. The results of this study show that seaweed fertilisation can increase barley grain sizes and δ³⁴S values, and thus should be considered when reconstructing land management and dietary practices in the archaeological record.

    Keywords: Sulfur stable isotope ratios (δ³⁴S), Seaweed, fertilisation, barley, Archaeobotany, SDG: Life on land

    Received: 15 Jul 2024; Accepted: 16 Oct 2024.

    Copyright: © 2024 Blanz, Gröcke, Martin and Church. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence:
    Magdalena Blanz, Austrian Academy of Sciences (OeAW), Vienna, 1030, Vienna, Austria
    Darren R. Gröcke, Department of Earth Sciences, Faculty of Science, Durham University, Durham, DH1 3LE, England, United Kingdom

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