Century-long soil profile truncation in eastern South Dakota agricultural fields

• Changes in soil morphology can be utilized to measure erosion rates when modern datasets are not available. • Erosion rates were likely higher at the later half of the 20th century compared to the first half. • Erosion rates can be highly variable in each field due landscape position. • Mollic epipedons are thinning due to erosion, which could lead to widespread alterations in soil classification and mapping. Soil loss remains a barrier to long-term sustainable agro-ecosystems. It is difficult to accurately quantify soil loss over multidecade time periods due to a lack of useful legacy data. Utilizing thirteen previously unseen soil survey descriptions of agricultural soils from the 1920′s and 1950′s in eastern South Dakota, USA, we quantify soil loss over the last century. Although the descriptions are missing nomenclature, they include marker features such as horizon depths, depth to carbonates, texture class, and depth to parent material. By revisiting and resampling the original locations, modern soil descriptions were utilized to assess the approximate 100-year changes in soil horizon thickness and morphological differences to quantify the amount of soil lost over the period. Changes in depth to carbonates, horizon depths and boundaries, texture changes and contrast, and depth to parent material were used to quantify the range in soil loss and potential mixing of subsurface and surface soil horizons. The average total amount of soil lost was 18.0 cm (1926 to 2023) and 14.9 cm (1955 to 2023). The resulting annual historical rates and masses of soil loss were between 1.9–2.2 mm yr −1 and 26.0–30.6 Mg ha yr −1 , which is comparable to regional studies that utilized shorter timescales. This study highlights the utility of legacy soil datasets as well as the importance of tracking long-term anthropogenic impacts for pedological modeling.