Design And Research Of Near Infrared Soil Moisture Measurement System

The detection of soil moisture plays an important role in agricultural production.By monitoring soil moisture in time,it is possible to analyze soil drought conditions in a timely manner,timely understand the growth and development of crops,and ensure agricultural production.The traditional near-infrared soil moisture detection scheme,the high-power consumption,high heat generation of the light source and the mechanical modulation mode of the light source transmitting signal,can no longer meet the requirements of rapid detection and real-time monitoring.Therefore,this paper studies a convenient and effective near-infrared soil moisture detection system that can quickly and accurately monitor soil moisture.The main research contents of this paper are as follows:1.Analyze the theoretical basis of the measurement of near-infrared soil moisture by consulting relevant technical data at home and abroad,including the formation of infrared spectrum,the absorption principle of near-infrared spectrum,and the near-infrared absorption spectrum of water.By analyzing the traditional near-infrared soil moisture detection method,some shortcomings are proposed.For example,the range of the emitted light band of the selected light source is far beyond the measurement needs,and the power consumption of the light source is large,the heat is serious,and the detection device is large.In order to improve these shortcomings,an improved near-infrared soil moisture detection scheme is proposed to meet the needs of convenient,fast and accurate detection.2.According to the measurement requirements,the near-infrared LED capable of emitting a specific wavelength is selected,and the process of modulating the broad-spectrum light source is omitted,and the volume of the detection probe can be further reduced.Through experiments,determine the height of the photodetector and the soil being tested.The design uses integrated chip,distributes the light source control circuit,output signal processing circuit and other related circuits on the same circuit board,writes the data acquisition program of the lower computer,and designs the data acquisition software.3.The stability test of the designed test system was carried out,and the conclusion that the measurement system has good stability was obtained.The calibration of the numerical model was carried out using soil samples of different humidity,and the determined coefficients of the segmentation fitting curves were 0.9105 and 0.9653,respectively.The soil samples with different humidity were used to verify the calibration curve.Finally,the correlation between the calculated values of the model and the actual soil water content was good.The coefficient of determination was 0.99 and the regression coefficient was 0.99,indicating that the numerical model can be used to predict soil moisture.Finally,the test system is repetitively tested,and the repeatability of the test system is 0.15%,which satisfies the measurement requirements.