| Cite this article: | 姚丽,王仰仁,王浩,等.电容式土壤温度水分盐分三参数传感器率定[J].灌溉排水学报,2020,(5):-. |
| YAO Li,WANG Yang-ren,WANG Hao,et al.电容式土壤温度水分盐分三参数传感器率定[J].灌溉排水学报,2020,(5):-. |
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| Calibration of soil temperature water and salt capacitive sensor |
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YAO Li, WANG Yang-ren, WANG Hao, LI Yong-lin, FAN Xin-rui
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College of Water Conservancy Engineering,Tianjin Agricultural University
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| Abstract: |
| Soil water content is important and commonly used information for farmland irrigation. It is the basis for regulating soil moisture conditions for water-saving irrigation, realizing scientific water use and irrigation automation, and has important guiding significance in the fight against drought and disaster reduction. The traditional method for determining soil moisture content is the drying method. Although this method is accurate, the method is more complicated and cannot provide real-time information in a timely manner. Therefore, many scholars at home and abroad have proposed a variety of methods for measuring soil moisture, such as neutron method, γ-ray transmission method, electromagnetic wave method, resistance method, capacitance method, photoelectric method and so on. The accurate use of instruments to test soil moisture content, soil electrical conductivity (ECa), and soil solution electrical conductivity (ECw) is essential for better management of irrigation water and effective monitoring and control of soil salinity. 【Objective】In order to test the accuracy of soil moisture content and conductivity measured by temperature and salinity three-parameter sensor (SMEC 300), 【Method】The soil moisture content and conductivity rated experiment were carried out in the farmland water cycle experiment base of Tianjin Agricultural University West Campus. Three water supply levels (2.65, 3.25, 3.8kg), four salt levels (salt content 0, 20, 70, 100 g) and six salinity gradients (1, 5, 10, 15, 20, 25 g/L) were set. Six plastic pots of the same volume shape were arranged at the test site. The dry soil in the basins was 8.85kg, the soil layer thickness was 10cm, and the sensor was buried 5 cm below the soil surface. During the test, the mass of the soil in the pot was regularly weighed to measure the actual water content of the soil; the conductivity test was also arranged in the same 6 pots, each of which was filled with 8L of water, and four sensors were placed in each pot. One processing was tested every 40 minutes. Soil moisture content and conductivity were calibrated respectively. 【Results】The results show that the electrical conductivity measured by the sensor has a significant exponential relationship with the degree of salinity, and the correlation coefficients were all above 0.92. The soil salinity affected the calibration of the soil moisture content, the actual water moisture content has a significant binary linear relationship with the soil moisture content and conductivity measured by the sensor, with the correlation coefficient being 0.9404 at the maximum and 0.6019 at the minimum, all reaching significant or extremely significant levels. The calibration parameters of different sensors were quite different. 【Conclusion】 Capacitive sensor has its corresponding parameters, which should be calibrated one by one. Soil salinity significantly affectd the accuracy of the sensor's. Therefore, the calibration of soil moisture content was effected and the scope of application of the capacitive sensor was broadened by importing electrical conductivity; the electrical conductivity measured by the sensor increased with the increase in salinity. There was a significant exponential relationship between electrical conductivity and salinity. |
| Key words: soil;moisture content,conductivity,calibrated,sensor |
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