Location: Soil Dynamics Research
Project Number: 6010-11120-008-15-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Nov 1, 2015
End Date: Oct 31, 2019
The overall goal is to improve the capabilities of the current Inelastic Neutron Scattering (INS) system and validate its usage for monitoring changes in soil carbon stores as a result of land use and management practices. The specific objectives of this proposal are: 1) to improve the capabilities (sensitivity and mapping) of the current INS system through engineering design changes; 2) calibrate and validate the improved system over different soil types and land use conditions; and 3) optimize and characterize the performance of the improved system.
The acceptance and adoption of agricultural land use practices that mitigate and adapt to climate change pressures depends on the productivity and profitability of the agricultural operations. Accurate and precise measurement and mapping of natural and anthropogenic variations in soil carbon stores is a critical component of the evaluation process. Current techniques to monitor carbon stores in the near surface are limited in sensitivity and resolution (both spatially and temporally). Traditional soil sampling and chemical analysis is expensive and time consuming, limiting their utility for long time scales and expansive coverage. These techniques are either incapable or impractical to measure small changes over time in response to land use or management practices. Inelastic Neutron Scattering (INS) has been demonstrated to be an integrating approach that provides wide-area monitoring over prolonged time periods in a simple manner. The INS system operates by detecting gamma-ray emissions from inelastic neutron scatterings and thermal neutron captures during irradiation. The sensitivity of the system is defined by the minimum detection limit (MDL) and the minimum detectable change (MDC). The MDL is defined as the number of gamma-ray counts above the background that differs from the background by a given confidence level. The MDC is defined as a change of three standard deviations in the signal level error. Both MDL and MDC can be enhanced by three ways: 1) increasing the sampling time; 2) increasing the signal counting rate; and 3) improving the shielding of the neutron generator from the detectors. The system will be calibrated using synthetic soils and validated against tradition core samples over different soil types and land use conditions. Sampling time will be optimized by analytical and experimental methods.