Location: Soil Dynamics ResearchTitle: Application of neutron-gamma technologies for soil elemental content determination and mapping
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/2/2023
Publication Date: 5/29/2023
Citation: Yakubova, G.N., Kavetskiy, A.G., Prior, S.A., Torbert III, H.A. 2023. Application of neutron-gamma technologies for soil elemental content determination and mapping [abstract]. International Conference on Nuclear Engineering Systems, Applications and Innovations (ICNESAI), San Francisco CA. 7-8 June.
Technical Abstract: In-situ soil carbon determination over large soil surface areas (several hectares) is required in regards to carbon sequestration and carbon credit issues. This capability is important for optimizing modern agricultural practices and enhancing soil science knowledge. Collecting and processing representative field soil cores for traditional laboratory chemical analysis is labor intensive and time consuming. The neutron-stimulated gamma analysis method can be used for in-situ measurements of primary elements in agricultural soils (e.g., Si, Al, O, C, Fe, and H). This is a non-destructive method that requires no sample preparation and can perform multi-elemental analyses of large soil volumes. Neutron-gamma soil elemental analysis is based on registration of gamma rays issued from nuclei upon interaction with neutrons; gamma rays are issued due to different processes of neutron-nuclei interactions. State-of-the-art nuclear physics methodologies and instrumentation, combined with commercial availability of portable pulse neutron generators, high-efficiency gamma detectors, reliable electronics, and measurement and data processing software, have currently made the application of neutron-gamma analysis possible for routine measurements in various fields of study. In Pulsed Fast Thermal Neutron Analysis (PFTNA), soil irradiation is accomplished using a pulsed neutron flux, and gamma spectra acquisition occurs both during and between pulses. This method allows the inelastic neutron scattering (INS) gamma spectrum to be separated from the thermal neutron capture (TNC) spectrum. Based on PFTNA, a mobile system for field-scale soil elemental determinations (primarily carbon) was developed and constructed. Our scanning methodology acquires data that can be directly used for creating soil elemental distribution maps (based on ArcGIS software) in a reasonable timeframe (~20-30 hectares per working day). Created maps are suitable for both agricultural purposes and carbon sequestration estimates. The measurement system design, spectra acquisition process, strategy for acquiring field-scale carbon content data, and mapping of agricultural fields will be discussed.