A new, open dataset for use with the DAYCENT biogeochemical model to assess both the impacts of land abandonment and the sustainability of olive groves under future climate scenarios in Andratx, Mallorca. The dataset is split into 3 main subsections: 1. ‘Field Data (Raw and Processed)’: This section contains the primary data which we collected in September 2025 that enable characterisation of managed vs abandoned terraced sites within the model, alongside details on data processing required for raw vegetation cover data (where this involved more extensive methods than the processing specified in the README file). This dataset contains (for both managed and abandoned sites) GPS coordinates, Soil pH, Relative Soil Nutrients (Nitrogen and Phosphorus), Soil Bulk Density (g/cm3), Soil Moisture (%), Soil Texture Fractions (fractions of Rock, Sand, Silt, Clay), Tree Height (m), and Vegetation Cover (% of each species). 2. ‘Secondary Data’: This section contains: Observed weather data: Daily data downloaded from the ECA&D dataset (https://www.ecad.eu/dailydata/ index.php – for station 26832). These were processed into the .wth format. Projected weather data: Due to file size constraints, these are not included directly. However, full datasets can be downloaded from AEMET’s climate projection archive (https://archivo-proyecciones-climaticas.aemet.es/). These downloads are downscaled daily precipitation, minimum temperature, and maximum temperature data for Illes Balears-Mallorca from four global climate models (GCMs): EC-Earth3-Veg, MIROC6, MPI-ESM1-2-HR, and MRI-ESM2-0, and under 4 Shared Socioeconomic Pathways (SSPs): SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5. R scripts (.R) used to process these downloads into the correct .wth DAYCENT format (in R Studios Version 4.40). Resulting weather files (.wth) used for spin-ups of the model (Observed, andratx_climate1.wth) and projections into the future (Projections, Outputs). Data on future atmospheric CO2 concentrations that were applied to our fix.100 file. Irrigation and fertiliser information supplied by the olive grove manager Sr Andres Liron (and then applied to irri.100 and fert.100 respectively). 3. ‘Model, Input, and Output Files’: The model set-ups are split according to our experimental approach (performing a spin-up pre-1950s land abandonment, then a modern baseline for abandoned and managed sites from 1951 to 2024, then projections). Each model set-up contains the DAYCENT executable files (DDcent_vDec2016.exe for running the model and DDcent_list100_vDec2016.exe for extracting data from the binary output file), the specific weather file (andratx.wth – taken from either Observed or Projected weather files), the specific schedule file (base.sch), and the specific input files (.100 or .in) that characterise the site and the events within that model set-up’s time period. This file set-up allows for model runs to be easily repeated. Although the input (and output) file names are the same across the 5 set-ups (again for easy reproduction of model runs), the file contents do differ between set-ups. Output files (.out) from each model run are also included. All outputs have been saved for now; only a subset will be used in our analysis. The base.bin files were used to extend the model runs from spin-up to baseline to projections. The spin-up binary file is base1145.bin, which is then used as an input for modern and abandoned baselines. The managed baseline produced base1455.bin, which is then used as an input for the managed projections. The abandoned baseline produced base1610.bin, which is then used as an input for the abandoned projections. Base1503.bin (managed) and base1633.bin (abandoned) are the binary file outputs of the projection run (for SSP1-2.6, EC-Earth3-Veg) without elevated CO2 ppm schedules; these projections will be rerun later to include the fix.100 CO2 ppm elevations. The projection setups are currently set for SSP1-2.6 and GCM ‘EC-Earth3-Veg’. To run the DAYCENT model under the 4 different SSPs from the 4 selected GCMs, andratx.wth and fix.100 have to be changed for each run. The full set of weather files are in the ‘Secondary Data’ folder and the fix.100 files in ‘Future CO2ppm scenarios (fix.100)’.