This dataset provides corrected bulk density (BD) values and their associated uncertainty estimates for 4,340 soil genetic horizons across 1,236 monitoring sites of the Hungarian Soil Information and Monitoring System. The correction was achieved by developing a pedotransfer function (PTF) based on the Hungarian Detailed Soil Hydro-physical Database (Hungarian acronym: MARTHA) and advanced machine learning algorithms. Soil properties (i.e., soil organic carbon, pH in water, and sand, silt, and clay content) together with environmental covariates, used as proxies for the soil forming factors, were integrated into the PTF development to improve predictive performance.Uncertainty of the BD predictions is provided in two forms: (1) the 90% prediction interval (defined by its lower and upper limits, within which the true value is expected to occur nine times out of ten), and (2) the standard error of the corrected BD values. To ensure transparency, reproducibility, and open access, the corrected BD values, their corresponding uncertainty estimates, and the developed code are publicly available.For more details / to cite this dataset please use:Sohrab, S., Szabó, B., Pásztor, L., Makó, A., Szatmári, G. (2025). Adjusting bulk density observations in the Hungarian Soil Information and Monitoring System using advanced pedotransfer functions. European Journal of Soil Science (submitted manuscript)Codes are available on GitHub:https://github.com/Mehrsoh/Soil-BD-CorrectionDescription of the files:Two versions of the same dataset are provided, differing only in file format: (1) "HUN-SIMS_BD_corrected.csv" – CSV format (separated by semicolon), and (2) "HUN-SIMS_BD_corrected.xlsx" – Microsoft Excel format. The table below summarizes the column names, units, and data formats, and also provides a description for each column. Note that the coordinate reference system is the Hungarian Unified National Projection System (HD72/EOV; EPSG: 23700). For more details, see https://epsg.io/23700.Column nameFormatUnitDescriptionPROFILE_IDstring-Identifier of monitoring sites in the Hungarian Soil Information and Monitoring SystemLAYER_IDstring-Identifier of soil genetic horizons at a monitoring siteXnumeric[m]X coordinateYnumeric[m]Y coordinateTOPnumeric[cm]Upper depth boundary of soil genetic horizonsBOTTOMnumeric[cm]Lower depth boundary of soil genetic horizonsBD_CORRECTEDnumeric[g·cm-3]Bias-corrected bulk density valueQ_05numeric[g·cm-3]5th quantile; lower limit of the 90% prediction intervalQ_95numeric[g·cm-3]95th quantile; upper limit of the 90% prediction intervalSEnumeric[g·cm-3]Standard error of the bias-corrected bulk density value

This dataset provides corrected bulk density (BD) values and their associated uncertainty estimates for 4,340 soil genetic horizons across 1,236 monitoring sites of the Hungarian Soil Information and Monitoring System. The correction was achieved by developing a pedotransfer function (PTF) based on the Hungarian Detailed Soil Hydro-physical Database (Hungarian acronym: MARTHA) and advanced machine learning algorithms. Soil properties (i.e., soil organic carbon, pH in water, and sand, silt, and clay content) together with environmental covariates, used as proxies for the soil forming factors, were integrated into the PTF development to improve predictive performance.Uncertainty of the BD predictions is provided in two forms: (1) the 90% prediction interval (defined by its lower and upper limits, within which the true value is expected to occur nine times out of ten), and (2) the standard error of the corrected BD values. To ensure transparency, reproducibility, and open access, the corrected BD values, their corresponding uncertainty estimates, and the developed code are publicly available.For more details / to cite this dataset please use:Sohrab, S., Szabó, B., Pásztor, L., Makó, A., Szatmári, G. (2025). Adjusting bulk density observations in the Hungarian Soil Information and Monitoring System using advanced pedotransfer functions. European Journal of Soil Science (submitted manuscript)Codes are available on GitHub:https://github.com/Mehrsoh/Soil-BD-CorrectionDescription of the files:Two versions of the same dataset are provided, differing only in file format: (1) "HUN-SIMS_BD_corrected.csv" – CSV format (separated by semicolon), and (2) "HUN-SIMS_BD_corrected.xlsx" – Microsoft Excel format. The table below summarizes the column names, units, and data formats, and also provides a description for each column. Note that the coordinate reference system is the Hungarian Unified National Projection System (HD72/EOV; EPSG: 23700). For more details, see https://epsg.io/23700.Column nameFormatUnitDescriptionPROFILE_IDstring-Identifier of monitoring sites in the Hungarian Soil Information and Monitoring SystemLAYER_IDstring-Identifier of soil genetic horizons at a monitoring siteXnumeric[m]X coordinateYnumeric[m]Y coordinateTOPnumeric[cm]Upper depth boundary of soil genetic horizonsBOTTOMnumeric[cm]Lower depth boundary of soil genetic horizonsBD_CORRECTEDnumeric[g·cm-3]Bias-corrected bulk density valueQ_05numeric[g·cm-3]5th quantile; lower limit of the 90% prediction intervalQ_95numeric[g·cm-3]95th quantile; upper limit of the 90% prediction intervalSEnumeric[g·cm-3]Standard error of the bias-corrected bulk density value

Here, we present a comprehensive isotope dataset of soil and stem xylem water collected during two pan-European sampling campaigns in spring and summer 2023. The dataset includes samples from 40 forest sites featuring beech (Fagus sylvatica), spruce (Picea abies), or mixed beech-spruce forests, and is supplemented with detailed site-specific, soil-specific, and tree-specific metadata. Samples and metadata were collected by various researchers across Europe following a standardized protocol. Soil samples were taken at up to five depths (ranging from 0 to 90 cm), and stem xylem samples were collected from three beech and/or spruce trees at each site. All samples were sent to a single laboratory for analysis, where water was extracted using cryogenic vacuum distillation and analyzed with an isotope laser spectrometer. Additionally, a subset of the samples underwent analysis with an isotope ratio mass spectrometer. The complete description of the data can be found in a publication in Earth System Science Data (in review).