Soil, fertilizer and plant density: Exploring the influence of environmental factors to stable nitrogen and carbon isotope composition in cereal grain.

Stable isotope analysis (N and C) of fossil cereal grains is regularly explored as a means of obtaining insights to past crop growing conditions and agricultural practices. In this study, we assessed how several growth conditions can affect δ15N and δ13C values of modern cereal grain with the aim to help understand isotopic values from ancient cereal remains. We investigated the impact of fertilizer intensity, plant density, and soil type on cereal grain δ15N and δ13C values in a short-term field experiment using hulled and naked barley, bread wheat, emmer wheat, einkorn, spelt wheat, rye, and oat. We found the following key results: 1) while fertilizing had a significant effect on δ15N values in grain, the impact varied between species, and cereals grown in heavy clay had consistently higher δ15N values in grain compared to those grown in light sandy soil, and 2) the δ13C values were significantly different between cereal species, but the difference was very similar between the two experimental site-locations. These findings obtained from plants grown under known conditions contribute to better understand how natural conditions and anthropogenic activities effect crop isotopic data and is of relevance for isotopic research on archaeological crop remains. • Field experiment assessing effects of growth conditions to cereal grain δ15N and δ13C values. • Effect of fertilizer intensity, plant density and soil type on crop isotope values. • Isotope analysis reveal cereal species are affected differently by experimental factors. • Soil type and fertilizer plays a profound role on crop δ15N values. • Difference in δ13C values between cereals similar at locations with different soils. [ABSTRACT FROM AUTHOR]