Abstract Long-term and multi-site datasets are essential for understanding crop responses to environmental variability and management practices, yet such data remain scarce, particularly for physiological indicators. Here, we present a harmonized dataset of analyses of stable carbon (i.e., δ 13 C values) and nitrogen (i.e. δ 15 N values) isotope ratios from winter wheat samples collected across ten long-term and short-term field trials in Europe. The dataset spans over 170 years (1850–2024) and includes sites in Switzerland, France, Germany, Denmark, and the United Kingdom. Samples originate from experiments encompassing unfertilized controls, mineral and organic nitrogen fertilization at multiple rates, and contrasting management systems, including conventional and organic practices. Grain samples were available for all selected years, with straw samples included when available. In addition to isotope ratios, the dataset provides harmonized management information, including sowing and harvest dates, nitrogen inputs, and yield data. Technical validation confirmed that management records and isotope ratios are agronomically and physiologically plausible and internally consistent across sites and years. This dataset offers a unique resource for investigating long-term (genotype by) environment by management interactions, benchmarking crop models, and conducting comparative analyses of carbon and nitrogen dynamics in European agroecosystems.