The continuous agricultural soil monitoring program (BDF) by the Saxon State Office for Environment, Agriculture, and Geology (LfULG) is operational since 1995, collecting and analysing samples periodically from 60 monitoring sites across Saxony, Germany. Mid-Infrared Diffuse Reflectance Infrared Fourier Transform Spectroscopy (mid-DRIFTS) is a promising analysis technique that allows for the determination of several soil properties simultaneously using chemometric models. For the calibration of such models, a Soil Spectral Library (SSL) including both soil spectra and analytical reference data is required. This dataset consists of soil spectra of 902 archive samples from the Soil Monitoring Program of the State Office for Environment, Agriculture, and Geology (LfULG), which were collected between 1995 and 2023, as well as soil spectra of 462 samples collected during an intensive sampling campaign in September 2023. Mid-IR spectra were recorded from 7500 cm⁻¹ to 400 cm⁻¹ at a resolution of 1 cm⁻¹ from air-dried and ground fine soil samples, using a Bruker Alpha II DRIFT with 32 device-internal replicate scans and averaging the spectra of four sample replicates. This dataset is part of a mid-infrared soil spectral library for agricultural soils in Saxony, Germany.