***Georeferenced point data of soil properties in the Netherlands***

Authors: Anatol Helfenstein, Vera L. Mulder, Mirjam J.D. Hack-ten Broeke, Maarten van Doorn, Kees Teuling, Dennis J.J. Walvoort, Gerard B.M. Heuvelink

Soil Geography and Landscape Group, Wageningen University, PO Box 47, 6700 AA Wageningen, the Netherlands
Soil, Water and Land Use Team, Wageningen Environmental Research, Droevendaalsesteeg 3, 6708 RC Wageningen, the Netherlands
Nutriënten Management Instituut, Nieuwe Kanaal 7C, 6709 PA, Wageningen, the Netherlands
Environmental Systems Analysis Group, Wageningen University, PO Box 47, 6700 AA, Wageningen, the Netherlands
ISRIC – World Soil Information, PO Box 353, 6700 AJ, Wageningen, the Netherlands

Corresponding authors:
A. Helfenstein (anatol.helfenstein@wur.nl)
V.L. Mulder (titia.mulder@wur.nl)
K. Teuling (kees.teuling@wur.nl)

Wageningen University and Research - Soil Geography and Landscape
PO Box 47
6700AA WAGENINGEN
The Netherlands

Date: 19-01-2024

Source:	Bodemkundig Informatie Systeem (BIS)
Format: .csv file
Type: Georeferenced spatial point data
Temporal coverage: 1953-2023
Spatial coverage: The Netherlands (national scale)
Projection: EPSG:28992 (Amersfoort / RD New), see https://epsg.io/28992
Language: English

***General Information***
This dataset contains georeferenced point data of basic soil properties in the Netherlands from the
"Bodemkundig Informatie Systeem" (BIS), the national soil database of the Netherlands. It includes
soil point data of clay content [%], silt content [%], sand content [%], bulk density (BD) [g/cm3],
soil organic matter (SOM) [%], pH [KCl], total N (Ntot) [mg/kg], oxalate-extractable P (Pox) [mmol/kg]
and cation exchange capacity (CEC) [mmol(c)/kg]. All of the soil properties were measured with
conventional laboratory methods. In addition to the laboratory measurements, there are also field
estimates made by soil surveyors for clay, BD and SOM. All laboratory measurements are part of the
"Profielbeschrijving" (PFB) dataset of BIS. Field estimates for clay, BD and SOM are mostly from the
"Boring Bodemkundige paket" (BPK) dataset of BIS, as well as some from the PFB dataset. Field estimates
from PFB for which there was a laboratory measurement available from the same location and depth were
removed from the dataset. All soil laboratory measurements and field estimates were collected by taking
soil samples in the field. Soil samples were taken by genetic soil horizons from depths between 0-2 m,
excluding the humus/litter/O horizon layer between 1953-2023.

All laboratory measurements of all 9 soil properties can be viewed at bodemdata.nl under "Profielbeschrijvingen
met analyses". All field estimates can be viewed via the same link under "Profielbeschrijvingen". Here you can
also find additional metadata and information of soil properties not included in this dataset. Part of the BIS
is also part of the National Key registry of the Subsurface (BRO) of the Netherlands. For more information on
subsurface data in the Netherlands you can also see this detailed manual: https://docs.geostandaarden.nl/bro/bhr-g/

***Description data in dataset***
Tabular datasets of each georeferenced soil property point data are provided as separate CSV files for
each soil property. The soil point data cover the entire Netherlands (national scale) and the spatial
projection of the provided X and Y coordinates is EPSG:28992 (Amersfoort / RD New), which is the national
projection most commonly used in the Netherlands. The columns provided in the CSV files are described as follows:
- BIS_tbl: dataset table in BIS
- BIS_type: observation quality (either laboratory measurement, i.e. "lab", or field estimate, i.e. "field")
- sample_id: ID of soil sample
- site_id: ID of sampling location
- X: x-coordinate of sampled location
- Y: y-coordinate of sampled location
- hor_nr: genetic soil horizon number
- hor: genetic soil horizon name
- d_upper: Upper boundary of sampled depth layer
- d_lower: Lower boundary of sampled depth layer
- d_mid: Midpoint of sampled depth layer
- year: Year in which soil sample was collected in the field
- clay_per: clay content [%]
- silt_per: silt content [%]
- sand_per:  sand content [%]
- BD_gcm3: bulk density (BD) [g/cm3]
- SOM_per: soil organic matter (SOM) [%]
- pH_KCl: pH [KCl]
- N_tot_mgkg: total N (Ntot) [mg/kg]
- P_ox_mmolkg: oxalate-extractable P (Pox) [mmol/kg]
- CEC: cation exchange capacity (CEC) [mmol(c)/kg]

***Scientific manuscript***
More information about these soil point data can be found in the associated scientific paper "BIS-4D: Mapping soil properties and their uncertainties at
25m resolution in the Netherlands" (Helfenstein et al., 2024, under review).

***GitLab code repository***
These data were downloaded from the BIS database, harmonized and prepared using R scripts, which can be found in the code repository on GitLab:
https://git.wur.nl/helfe001/bis-4d.
These data were further used for digital soil mapping as part of the BIS-4D soil modelling and mapping platform (see Helfenstein et al., 2024, under review
and https://git.wur.nl/helfe001/bis-4d for the code of BIS-4D)

***Acknowledgements & funding***
We would like to thank Joop P. Okx for envisioning and realizing the need for spatially explicit soil property information
in the Netherlands and his involvement in the early stages of this project. We thank Fokke de Brouwer for his expertise on soil surveying
and mapping in the Netherlands. Furthermore, we thank Dorothee van Tol-Leenders and WENR colleagues for their ongoing efforts to
ultimately integrate 630 BIS-4D maps on https://bodemdata.nl. We express our utmost gratitude to all data providers. This includes decades of
rigorous work by soil surveyors and scientists from the Stichting Bodemkartering (StiBoKa), the DLO Winand Staring Centre for Integrated
Land, Soil and Water Research, later known as Alterra, and Wageningen Environmental Research. And lastly this includes the providers of
data used to derive hundreds of different covariates for this study, made available from different sources and by various institutions. This
project (WOT-04-013-010) was financed by the Dutch Ministry of Agriculture, Nature and Food Quality: https://research.wur.nl/en/projects/
635 soil-property-mapping-wot-04-013-010.

***Video supplement***
A short research pitch of BIS-4D is available here: https://www.youtube.com/watch?v=ENCYUnqc-wo


