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ARS Home » Southeast Area » Auburn, Alabama » Soil Dynamics Research » Research » Publications at this Location » Publication #351785

Research Project: Enhancing Production and Ecosystem Services of Horticultural and Agricultural Systems in the Southeastern United States

Location: Soil Dynamics Research

Title: Scanning mode application of neutron-gamma analysis for soil carbon mapping

item KAVETSKIY, ALEKSANDR - Auburn University
item Yakubova, Galina
item SARGSYAN, NIKOLAY - Auburn University
item WIKLE, CLYDE - Auburn University
item Prior, Stephen - Steve
item Torbert, Henry - Allen
item CHIN, BRYAN - Auburn University

Submitted to: Pedosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2018
Publication Date: 5/15/2019
Citation: Kavetskiy, A., Yakubova, G.N., Sargsyan, N., Wikle, C., Prior, S.A., Torbert III, H.A., Chin, B.A. 2019. Scanning mode application of neutron-gamma analysis for soil carbon mapping. Pedosphere. 29(3):334-343.

Interpretive Summary: Capturing atmospheric carbon via plant growth can help mitigate global change through soil carbon storage. A novel carbon measuring device called a mobile inelastic neutron scattering system (no soil sampling required) working in scanning mode was demonstrated. The veracity of scanning was proven by its agreement with static mode and chemical analysis results. Our current system can produce good soil carbon maps when scanning time of a defined area is ~15 minutes. Future work will center on increasing the number of detectors to map larger land areas in a timely fashion.

Technical Abstract: Applications of neutron-gamma analysis in the scanning mode for mapping of soil carbon are discussed. The GPS device and software required to simultaneously acquire gamma signals and geographical positions during scanning operations were added to an existing measurement system. The reliability of soil carbon measurements in the scanning mode was demonstrated to be in agreement with results acquired from static mode measurements and traditional soil chemical analysis. Error analysis indicated that scanning measurements can be conducted with the same accuracy as static measurements in approximately ¼ the time. To obtain soil carbon measurement errors suitable for mapping and analogous to traditional chemical analysis (i.e., ±0.5 w%), scanning time over a given site should be ~15 min using our current measurement system configuration. Based on this measurement time, a reasonable towing speed of 3-5 km/h, and the necessity for complete site coverage during scanning, the number of sites (within the surveyed field) and required total measurement time can be estimated. Soil carbon measurements for 28 field sites (total area ~2.5 ha) were conducted in ~8 hours. Based on acquired data, a soil carbon distribution map was constructed utilizing ArcGIS, IGOR, and Google Earth Pro software. The surveyed field area included asphalt roads that had carbon readings higher than surrounding land. The clarity with which these carbon rich zones are delineated on the constructed map is evidence supporting the veracity of this method. Soil carbon mapping can be useful in assessing the impact of agricultural and other land management practices on soil carbon storage, and neutron gamma analysis technology can greatly facilitate timely construction of these maps.