Abstract Here we present an updated version of radiocarbon concentrations measured in seeds from the Gatersleben Crop Plant Research institute. 14 C-isotope measurements for wheat from 1946 to 2020, which were presented previously, have been complemented with 14 C measurements made on soybean and continued until late summer 2025. Additionally, we measured δ 13 C in wheat samples. A comparison of different 14 C time series over the last 80 years from different regions such as the Colorado Plateau (herbaria archived annual plants; Carbone et al. 2023), England (Barley; Dunbar et al. 2024), and Germany (Gatersleben seed, this study) reveal 14 C discrepancies during peak bomb-period with reference atmospheric 14 C data, i.e., the Northern Hemisphere Zone 1 & 2, and may indicate a heterogenous atmospheric 14 C composition, i.e., admixture of different air masses with a slightly divergent 14 C composition.
Huels et al. (Mon,) studied this question.