The dataset includes information on soil properties collected from two conventionally managed fields under corn-soybean rotation in October 2005 and October 2016, respectively. The fields are located in Story County, Central Iowa. 42 sampling locations per field and year were sampled within a 50 m × 50 m grid, and 1 to 2 samples per location were collected using a hydraulic soil sampler (d= 38.2 mm) from the 0 - 120 cm soil layer. The samples were analyzed to determine carbon and nitrogen concentration, and soil pH in five soil layers (0-15, 15-30, 30-60, 60-90, and 90-120 cm). Presented is the raw data per location (mean of duplicates) with which carbon and nitrogen content can be calculated with either the equivalent soil mass method or by using bulk density.