Submitted to: Journal of Visualized Experiments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/24/2017
Publication Date: 8/16/2017
Citation: Yakubova, G.N., Kavetskiy, A.G., Prior, S.A., Torbert Iii, H.A. 2017. Measurements of soil carbon by neutron-gamma analysis in static and scanning modes. Journal of Visualized Experiments. 126:e56270. https://doi.org/10.3791/56270.
DOI: https://doi.org/10.3791/56270

Interpretive Summary: Carbon is an integral part of the atmospheric-terrestrial carbon exchange cycle mediated by plants. More soil carbon promotes good soil stewardship by improving water/nutrient retention, soil structure, and maintenance of clean water through erosion prevention. Capture of atmospheric carbon via plant growth could mitigate global change through more storage of carbon in soil. These benefits hinge on accurate measurement of soil carbon to help identify best soil management practices. This work examines a mobile device that uses neutron-gamma analysis for fast and nondestructive measurement of soil carbon. We compared soil carbon measurements in both static (stationary) and scanning (moving) modes.

Technical Abstract: The herein described application of the inelastic neutron scattering (INS) method for soil carbon analysis is based on the registration and analysis of gamma rays created when neutrons interact with soil elements. The main parts of the INS system are a pulsed neutron generator, NaI(Tl) gamma detectors, split electronics to separate gamma spectra due to INS and thermo-neutron capture (TNC) processes, and software for gamma spectra acquisition and data processing. This method has several advantages over other methods in that it is a non-destructive in situ method that measures the average carbon content in large soil volumes, is negligibly impacted by local sharp changes in soil carbon, and can be used in stationary or scanning modes. The result of the INS method is the carbon content from a site with a footprint of ~3 m2 in the stationary regime, or the average carbon content of the traversed area in the scanning regime. The measurement range of the current INS system is >1.5 carbon weight % (standard deviation ±0.3) in the upper 10 cm soil layer for a 1 hour measurement.