Study On Soil Moisture Content Based On Infrared

Water resource is one of the most important factors restricting agricultural production inarid, semi-arid regions of Northwest China, value theory research not only has higher in soilmoisture monitoring, but also is essential for agricultural production practice of localsignificance. Therefore, timely and accurate collection plays a very important role inmonitoring the soil moisture content.It is feasible to detect the moisture contents indirectly by testing the dielectric constant ofgrains because the dielectric properties of grains have a close relationship with their moisturecontents. The mositure constant of soil are not only decided by their temperature, but alsorelated with some other factors such as environmental temperature，humidity and solarradiation rate. Based on the above reasons, soil moisture content is designed based on infraredin this paper, considering the impact of environmental temperature，humidity and solarradiation rate on detection accuracy. The main research contents and the results are as follows.（1）Temperature and moisture content of soil in different depth were measured atdifferent time，results showed that there was a good linear relationship between the averagesoil moisture content and temperature in depth from0to20cm, and the correlationcoefficient R2was0.658. The correlation coefficient R2between the moisture content ofsurface soil and the temperature was0.794at noon in the case of small changes occurred inthe external environment.（2）The methods are the same as the first experiment. Through a lot of experimentsand data analysis of soil temperature, environmental temperature and humidity and solarradiation rate, established the mathematical model between soil water content and soiltemperature and environmental factors, verified the rationality of the model. The accuracyof the model obtained is79.58%，the maximum absolute error of measured value and thepredicted value is3.04，the minimum error is0.19.（3）The hardware system of moisture content system was designed. The systemconsisted of8-bit Single-chip Microcomputer AT89S52, soil temperature detection module,solar radiation detection module, environmental temperature and humidity detection module and input-output module. The system could show the soil moisture content calculated on thebase of detecting soil temperature, solar radiation rate and environmental temperature andhumidity.（4）The software system of moisture content system was programmed using C51language, including main procedure, environmental temperature and humidity measurementprocedurs, soil temperature measurement procedurs, Liquid Crystal Display procedure,keyboard input procedure and moisture content calculation procedure.（5）The Printed Circuit Board of moisture content meter was designed by AltiumDesigner. Then the hardware system was made and the software system was debugged.