Wednesday, November 7, 2007
305-18

Feasibility of Measuring Soil Moisture Content Using the Inelastic Neutron Scattering (INS) Carbon Analyzer.

Sudeep Mitra1, Lucian Wielopolski1, Rex Omonode2, Oded Doron3, Jeffrey Novak4, and James Frederick5. (1) Environmental Sciences Department, Brookhaven National Laboratory, Upton, NY 11973, (2) AgCert Services (USA) Inc., 1901 S Harbor City Blvd., Suite 400, Melbourne, FL 32901,, (3) Nuclear Engineering, The University of Texas at Austin, 1 University Station, Austin, Austin, TX 78759, (4) USDA-ARS, USDA-ARS-Coastal Plains Research Center, 2611 W. Lucas Street, Florence, SC 29501-1241, (5) Clemson University, Pee Dee Res. & Education Ctr., 2200 Pocket Rd., Florence, SC 29506-9706

Knowledge of soil carbon (C) and moisture contents is vital for crop and soil management. Current techniques for measuring these components require independent techniques that could be labor intensive and time consuming. The prospect of simultaneously measuring the soil C and moisture content in real - time using the INS system has been explored in this study. The system utilizes a 14 MeV neutron generator (NG) operated in the pulsed mode, whereby C, H and O in the soil is determined by measuring their characteristic gamma - ray emission following their interaction with neutrons. Laboratory experiments were conducted at the Soil Analysis Facility at Brookhaven National Laboratory, and field experiments were carried out at the Pee Dee Clemson University Research Station in Florence, South Carolina. In the field experiment, C, H and O were measured by the INS instrument at ten sites that represented different landscape positions ranging from the foot slope to upslope and across different soil types. At each site, volumetric soil moisture content was measured using the theta probe and gravimetric moisture content measured on samples collected to 30 cm depth. We present preliminary data on the relationship between the H and O signals and soil moisture content.