Time domain reflectometry: laboratory and field calibration for soil moisture content and salinity.
Carlos G. Ochoa1, Manoj Shukla2, Alexander Fernald1, and Steven Guldan3. (1) New Mexico State University, Department of Animal and Range Sc, MSC 3-I, P.O. Box 30003, Las Cruces, NM 88003, (2) New Mexico State University, Department of Plant and Environmental Sc, MSC 3-Q, P.O. Box 30003, Las Cruces, NM 88003-8003, (3) PO Box 159, New Mexico State University, New Mexico State University, Alcalde Science Ctr., Alcalde, NM 87511
Soil moisture content is an important parameter for agricultural, hydrological and meterorological research. Simultaneous monitoring of changes in soil moisture content and solute concentrations is important for assessing the effects of salinity on plant and attendant environemnt. We calibrated a new Time Domain Reflectometry (TDR) sensor for different levels of soil moisture and salinity in the Lab for a sand and a sandy loam soil. Eight different input solute concentrations ranging from 0.5 dS m-1 to 7 dS m-1 were used to measure and predict bulk soil electrical conductivity (ECb). We used several conceptual and diffusion models to predict ECb. Our objectives of the research are to: (1) test various models used to express ECb as a function of water content, tortuocity and solution concentration, and (2) suggest the model that best estimates the measured ECb using a TDR for those two soil types.