Design Of Soil Moisture Monitoring System Based On Wireless Underground Sensor

Soil moisture accurate, continuous, real-time monitoring is a prerequisite to achieve precision irrigation and agricultural water use efficiency. The traditional soil moisture monitoring system is mainly laid on the soil surface, when tilling the soil, surface monitoring systems need to bypass such tillage inconvenient. Traditional farmland soil moisture monitoring system, set up inconvenient issues, designing and developing a suitable farmland soil moisture based wireless underground sensor monitoring system. The system can ensure that at least 15 days buried in the soil, does not affect the Tillage, set up and easy to maintain, provide basis for decision making for precision crop water-saving irrigation. Based on the needs analysis, complete the hardware design and software design, and by drying method for determination of soil moisture sensor calibration equation, the soil moisture content measured with higher accuracy. The main results of this article are included as follows:(1) The establishment of a low-power hardware system as a starting point. NORDIC wireless communication module using the company’s NRF905 wireless module, which operates in the 433 MHz ISM band, the microprocessor chip selection STC89C52, moisture sensor for low power consumption and the use of FDS-100 frequency domain measurements of soil moisture sensor technology. Hardware circuit design and complete underground and ground nodes.(2) The development of data acquisition, software program each node data transmission, data reception, etc., to achieve the acquisition, wireless transmission of soil moisture content, receive and upload to the computer PC. Using VB(Visual Basic) 6.0 completed the PC software. PC real-time display of the soil moisture data received and acquisition time and use map soil moisture profile.(3) Complete test system in the wheat field trials. In the experimental field of winter wheat heading(average height 0.8m), the weather is sunny, daytime temperatures 27 ℃, lower wind class 2 to 3 cases, the nodes were buried underground in wheat soil 30 cm, 45 cm, 60 cm deep, measured from the horizontal transfer were 27.4m, 18 m, 11.5m; and corresponds deep collected soil water content and soil depth comparison of the actual values obtained by the drying method, the average percentage error of 2.25%, 1.96%, 2.36%, average percentage error is less than 3%, provide the basis for agricultural water-saving irrigation.(4) Monitoring system uses a large capacity battery powered, the battery pack with a total capacity 12000 mA, long time buried in the soil. After testing, the monitoring system has been in the underground node unattended, underground collection rate of more than 15 days the soil moisture, meet the design requirements of the system.