Monitoring and Control of Relative Humidity in Soil using LabVIEW

The key objective of our paper is to monitor the soil’s moisture content during it’s dry and wet conditions with the aid of a moisture sensor circuit, calculate the corresponding Relative Humidity and irrigate it based on its nature , using a PC based LabVIEW system, NI ELVIS and an automatic water inlet setup. The moisture sensor circuit which is built on the NI ELVIS consists of two copper strips as probes, to sense the soil’s condition. The sensed signal from the NI ELVIS is interfaced to a PC with LabVIEW using a PCI 6221 cable. A LabVIEW block diagram is constructed which acquires this signal as a voltage and displays the numerical value, the equivalent relative humidity and a filtered waveform graph in the front panel. The acquired voltage is then generated in LabVIEW, the mechanism by which with a help of a relay circuitry, a submissive pump turns on automatically to irrigate at the soil’s dry condition, and turns off when wet as sensed by the probes. A record of the relative humidity is also stored in an EXCEL file format for backup. KeywordLabVIEW, NI ELVIS, Relative Humidity, Soil, Moisture