Triple Probe Heat Pulse (TPHP) Soil Moisture Content and Temperature Monitoring Digital System Using Nanomaterials based Sensor Elements for Precision Agriculture

I discuss the TPHP soil moisture content and temperature measuring digital system using Indium doped Tin Oxide nanopowder (ITO) electric heater and Nickel manganite (NiMn2O4)nanoceramic powder thermistor as a temperature sensor fabrication, characterization, calibration, and testing. The NiMn2O4 nanoceramic powder is synthesized using the wet chemical method and the ITO nanopowder-based heater is fabricated by a simple fill and press method. The heater, temperature sensor, Atmega 328 microcontroller with its software, stainless steel cylindrical tubes, and 3D-printed package are used to fabricate the device. The distance between the heater and the temperature sensor is set to 0.006 m and heat pulse duration is set to 240 s. The heater consumes 3.587W electric power. The temperature sensor can measure the soil temperature up to 50 degrees C. The system is capable of measuring volumetric soil moisture content from 3% to 37% efficiently with a strong correlation coefficient of 0.997 with respect to the standard. The test result shows that there is less than a 2.8% error which is the smallest among the category and the sensitivity of the sensor at volumetric soil moisture content (theta(v)) = 0.28m(3) m(-3) becomes 3.14 degrees C per m(3) m(-3). The developed system is simple to fabricate and operate highly precise, low cost, low power and light in weight.