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    • Data From: Gamma-Spectroscopy Method for Soil Water Content Estimation in an Agricultural Field

    Metadata Updated: April 21, 2025

    Gamma-ray spectroscopy (GRS) enables continuous estimation of soil water content (SWC) at the subfield scale with a noninvasive sensor. Hydrological applications, including hyper-resolution land surface models and precision agricultural decision making, could benefit greatly from such SWC information, but a gap exists between established theory and accurate estimation of SWC from GRS in the field. In response, we conducted a robust three-year field validation study at a well instrumented agricultural site in Nebraska, United States. The study involved 27 gravimetric water content sampling campaigns in maize and soybean and 40K specific activity (Bq kg−1) measurements from a stationary GRS sensor. Our analysis showed that the current method for biomass water content correction is appropriate for our maize and soybean field but that the ratio of soil mass attenuation to water mass attenuation used in the theoretical equation must be adjusted to satisfactorily describe the field data. We propose a calibration equation with two free parameters: the theoretical 40K intensity in dry soil and a, which creates an “effective” mass attenuation ratio. Based on statistical analyses of our data set, we recommend calibrating the GRS sensor for SWC estimation using 10 profiles within the footprint and 5 calibration sampling campaigns to achieve a cross-validation root mean square error below 0.035 g g−1.

    Access & Use Information

    Public: This dataset is intended for public access and use. License: Creative Commons Attribution

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    Dates

    Metadata Created Date May 31, 2024
    Metadata Updated Date April 21, 2025

    Metadata Source

    Harvested from USDA JSON

    Other Data Resources

    Additional Metadata

    Resource Type Dataset
    Metadata Created Date May 31, 2024
    Metadata Updated Date April 21, 2025
    Publisher Agricultural Research Service
    Maintainer
    Identifier 10.15482/USDA.ADC/25723959.v1
    Data Last Modified 2024-05-23
    Public Access Level public
    Bureau Code 005:18
    Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
    Schema Version https://project-open-data.cio.gov/v1.1/schema
    Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
    Harvest Object Id 5a380774-dde7-404c-ad95-2d01f7a468cc
    Harvest Source Id d3fafa34-0cb9-48f1-ab1d-5b5fdc783806
    Harvest Source Title USDA JSON
    License https://creativecommons.org/licenses/by/4.0/
    Old Spatial {"type": "Point", "coordinates": -96.4397, 41.1797}
    Program Code 005:040
    Source Datajson Identifier True
    Source Hash fd6589ade26b7d1d0afb362f7293fccb79d6375a6403c3236ec978c208b18e7b
    Source Schema Version 1.1
    Spatial {"type": "Point", "coordinates": -96.4397, 41.1797}
    Temporal 2021-07-19/2023-10-23

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