Fundamental advantage Shortcomings Remote Sensing The reverse electromagnetic wave intensity of soil with different water content is different Large range of measurements Only a few centimeters of soil below the ground can be measured and based on fixed-point measurement data, the accuracy of measured data is not high. GPR method The propagation speed of electromagnetic waves in soil corresponds to the dielectric constant of soil Larger measurement range Only a few centimeters of soil below the ground can be measured and based on fixed-point measurement data, the accuracy of measured data is poor Drying method The soil was dried at about 105°C, and the moisture content was directly calculated to determine the soil moisture content. Low cost, simple, high accuracy It takes time and effort, and destroys the soil at the measurement point, which is not conducive to in-situ measurement. The sampling process will cause evaporation error. Neutron moisture meter Calculate soil moisture measurements by recording the number of fast neutrons that have similar mass hydrogen atoms as slow neutrons Representative, high accuracy of measurement data, moderate instrument prices The measured slow neutron number depends on the conversion of the standard curve to water content. The calibration process will introduce errors and have radiation hazards. Time domain reflectometry The propagation speed of electromagnetic waves in soil medium corresponds to the dielectric constant of soil Quick and accurate, continuous automatic monitoring of in-situ soil Measurements need to be corrected and expensive Γ-ray method When γ-ray penetrates the soil, the degree of energy decay corresponds to the soil moisture content. Fast, accurate, continuous automatic monitoring of soil measurements Affected by the dry density of the soil, only suitable for laboratory determination Tension meter method The negative pressure of the negative pressure tube corresponds to the soil suction Cheaper, simpler operation for long-term monitoring of in-situ soils Affected by the temperature, it will fail when the soil moisture content is low, and the water in the negative pressure will bring error to the soil. Dew point microvoltmeter method The temperature of the thermocouple probe is measured by the electrical method, and the linear function that the specific temperature is the water potential of the measured interval is discussed. It can measure the low soil water potential and can measure long-term monitoring value of in-situ soil Affected by temperature changes very much, the measurement error is very high when soil moisture is high Resistance method Resistance changes correspond to surrounding soil water potential cheap price Sensitive to soil type, salt concentration and soil temperature, the measurement range varies with different resistance blocks Professional measuring instruments (multifunctional soil moisture recorder, multi-point soil moisture monitoring system) Using sensors to measure soil moisture Real-time monitoring of soil moisture changes and curve analysis of measurement results The result of the measurement is influenced by the salinity in the soil PPR Pipe Fitting Mould Taizhou Huangyan YouGo Mould & Plastic Co., Ltd , http://www.plastic-moulds.com
test methods
Principles and advantages and disadvantages of 10 methods for measuring soil moisture The soil moisture measurement has always been noticed by people from all walks of life. Accurate measurement of soil moisture is important in precision irrigation. The method of measuring soil moisture is roughly determined from the spatial scale of measurement. Can be divided into fixed-point determination and large-area measurement of two ways, these two measurement methods can be divided into several, the former can be divided into four measurement methods, these four measurement methods are more common, and the latter measurement method can be divided into Ground penetrating radar (GPR) measurements and remote sensing measurements. The principle, advantages and disadvantages of various types of measurement methods are as follows: