Research On Soil Moisture Monitoring System

China is a great agricultural country while water resources are in short supply.A large amount of water is required in agricultural production,and abundant soil moisture is a significant support allowing high agricultural production.Resulting from the increasing shortage of water resources,water-saving agriculture is now an emergency.Moreover,soil moisture content is also closely concerned with landslide,mountain collapse,floods and other disasters.Consequently,accurately monitoring the soil moisture content promptly is of great importance on crop growth and pre-warning geological disasters,etc.Currently,methods to monitor soil moisture are mainly manually on-site measurement or on-site measurement with detection instruments.However,the measurement accuracy is relatively in deficiency without an intelligent monitoring system.In order to solve the above problems to rapidly and accurately collect and real-time monitor the soil moisture,this paper conducts a research on soil moisture monitoring system by studying and analyzing soil moisture monitoring methods,as well as current states and development trends of research at home and abroad.The soil moisture monitoring system designed in this paper is divided into two parts,detection terminal and monitoring terminal.Theoretically analyzing the dielectric characteristics of the soil,Standing Wave Ratio is determined as the measurement method of soil water content and the measurement frequency option is accomplished.The structure of detection terminal is analyzed according to the actual situation while monitoring so as to achieve the hardware and software design of detection terminal.This paper adopts multiple sets of metal rings as sensing detectors for multi-depth monitoring,and finite element simulation analysis and parameter optimization on the structure of ring metal detectors;adopts DDS technology and time-division multiple detection to design the signal source and detection circuit of detection terminal;adopts solar energy to supply power for detection terminal;adopts GPRS technology to complete the communication between detection terminal and monitoring terminal so as to realize intelligent operations like automatic monitoring and remote control of soil moisture content.Detection terminal uploads the collected information to the cloud platform of monitoring terminal for data transfer.The cloud platform cleans and converts the received data and stores data in historical information database and foreground reading database respectively.The data background service module displays and interacts the foreground-reading data and historical data on the client.This paper adopts least-squares method to make polynomial fitting on the voltage output from detection terminal and the standard soil water content measured by the drying method to reach a relation model between soil and moisture.Designing experiments to analyze the system performance,the experiments' results reveal that the measurement deviation of the soil moisture monitoring system designed and studied in this paper is less than 3%,with a good consistency and stability.