SSP.460 Dataset
==============

Description
-----------
* Target Soil Properties: SOC, pH, Clay
* Groups of Features: vis-NIR
* Sample Size: 460
* Number of Features: 830
* Coordinates: Without coordinates because of privacy concerns
* Location: State of Sao Paulo, Brazil
* Sampling Design: Regular grid sampling
* Study Area Size: 473 ha
* Geological Setting: Predominantly sandstones with some basaltic flows
* Previous Data Publication: None
* Contact Information:
    * Leonardo Ramirez Lopez (Ramirez-Lopez.L@buchi.com), BÜCHI Labortechnik AG
* License: CC BY-SA 4.0
* Publication/Modification Date (d/m/y): 28.02.25, version 1.0
* Changelog:
    * Version 1.0 (28.02.25): Initial release

Details
-------

Dataset
^^^^^^^
The dataset contains the following target soil properties and features:

Target Soil Properties:
""""""""""""""""""""""

SOC - Soil Organic Carbon
    * Code: ``SOC_target``
    * Unit: %
    * Protocol: Measured through titration after oxidization of the organic carbon (Walkley & Black 1934)
    * Sampling Date: Unknown month 2000
    * Sampling Depth: 0 - 20 cm

pH
    * Code: ``pH_target``
    * Unit: Unitless
    * Protocol: Measured in water suspension with a glass electrode with unspecified liquid:soil ratio
    * Sampling Date: Unknown month 2001
    * Sampling Depth: 0 - 20 cm

Clay
    * Code: ``Clay_target``
    * Unit: %
    * Protocol: Hydrometer method; separation of the fractions by sieving and sedimentation. Measurement of the separated fractions by weighing the density of the suspension (Gee and Bauder 1979)
    * Sampling Date: Unknown month 2001
    * Sampling Depth: 0 - 20 cm

Groups of Features:
"""""""""""""""""

vis-NIR – Visible and Near Infrared Spectroscopy
    * Number of Features: 830
    * Code(s): ``wl_350``, ``wl_352``, ``wl_354`` ... ``wl_2498``
    * Unit: % (Reflectance)
    * Sensing: Infra-red intelligent spectroradiometer-IRIS MkIV (Geophysical and Environmental Research Corporation, New York, USA), on dried samples in the laboratory, spectral range was 350 – 3,000 nm at 2 - 5 nm intervals
    * Processing: Discarding noisy edges of the spectrum (2,458 - 3,000 nm)
    * Sampling Date: Unknown month 2001
    * Spectral Information (After Data Processing):
        * Data Representation: Wavelength (in nm)
        * Spectral Resolution: 2 - 5 nm depending on wavelength range
        * Spectral Range: 350 – 2,498 nm

Examples
--------

.. code-block:: python

    # Load and explore the dataset
    data = load_dataset("SSP.460")
    dataset = data["Dataset"]
    folds = data["Folds"]
    coords = data["Coordinates"]  # Note: No coordinates available

    # Split into train/test using fold 1
    X_train, X_test, y_train, y_test = split_dataset(
        data=data,
        fold=1,
        targets=["pH_target", "SOC_target", "Clay_target"]
    )

    # Calculate model performance
    predictions = model.predict(X_test)
    metrics = calculate_performance(y_test, predictions)
    print(f"R2: {metrics['r2']:.3f}, RMSE: {metrics['rmse']:.3f}")

References
----------

Gee, G. W., & Bauder, J. W. (1979). Particle size analysis by hydrometer: a simplified method for routine textural analysis and a sensitivity test of measurement parameters. Soil Science Society of America Journal, 43(5), 1004-1007.

Walkley, A. & Black, I. A. (1934). An examination of the Degtjareff method for determining soil organic matter, and a proposed modification of the chromic acid titration method. Soil science, 37(1), 29-38.