Soil Moisture Sensor for Use in Polar Regions

摘要

The feasibility of a potentially inexpensive sensor for the measurement of the moisture content of soil was investigated. The moisture sensing techniques implemented by the sensor theoretically gave the instrument the capability to discriminate permafrost from liquid moisture in the soil. A prototype soil moisture sensor was developed by adapting pre-existing hardware to the application. The prototype instrument was used to investigate the possibility of using dual low-frequency capacitive measurements to quantify total soil moisture content in volumetric units of grams per cubic centimeter. Laboratory tests were conducted using liquid water, ice, and soil samples. The tests indicate that the theory is correct but two interfering effects limit the usefulness of the probe--dialectric polarization due to space-charge buildup, and soil binding energy.