摘要
为探究电流-电压四端法和时域反射法两种接触式测量方法在不同质地土壤和不同含盐量、含水率土壤的适用性,设计基于"电流-电压"四端法的土壤电导率测量仪,对其标定并与时域反射法进行对比试验。标定结果表明,当电导率在0~14mS/cm范围内时,该仪器具有较高准确度。不同含水率的对比试验结果表明,四端法和时域反射法在一定含盐量范围内都具有较好的线性度;而当砂质壤土含水率为20%、含盐量大于0.6%时,四端法电导率测量仪测得的电导率基本保持不变;当粉质黏土含水率较低和较高时,电导率均变化不大,因此在使用时应尽量避免在土壤含水率较低和较高时进行测量。不同质地土壤的对比试验表明,四端法和时域反射法均在含盐量较低时受土壤质地影响较小,在含盐量较高时受土壤质地影响较大。
Obtaining farmland information quickly and efficiently is the basis of precision agriculture."Current-voltage" four-terminal method and time domain reflectrometry (TDR) are two main methods for contact measurement of soil conductivity.A soil conductivity instrument based on the principle of "current-voltage" four-terminal method was designed,which was calibrated and compared with TDR to explore the applicability of the two methods.The calibration results showed that when the electrical conductivity was in the range of 0 and 14 mS/cm,the determination coefficient R 2 reached 0.960,and the instrument had high accuracy in this range.The results of soil contrast test showed that the four-terminal method and TDR had good linearity under the condition of low salt content and water content,but when the salt content of sandy loam was more than 0.6%,the change of conductivity measured by four-terminal method tended to be smooth.When the moisture content of silty clay was 20% and 25%,the measurement data of the two instruments were basically the same,so it was needed to try best to avoid measuring when the soil moisture content was high.The comparative experiments under different texture soils showed that the four-terminal method and TDR were greatly affected by the soil type,and the higher the clay content of the soil was,the smaller the conductivity of the soil was.During the test,the four-terminal conductivity meter can measure in real time,but the time of each TDR measurement was about 20 s,which was not conducive to real-time measurement.
作者
魏鸿怡
孟繁佳
WEI Hongyi;MENG Fanjia(Key Laboratory of Modern Precision Agriculture System Integration Research,Ministry of Education,China Agricultural University,Beijing 100083,China)
出处
《农业机械学报》
EI
CAS
CSCD
北大核心
2019年第B07期237-242,共6页
Transactions of the Chinese Society for Agricultural Machinery
基金
国家自然科学基金项目(31401294)
国家重点研发计划项目(2018YFD010100202)
关键词
土壤电导率
四端法
时域反射法
测量
soil electrical conductivity
four-terminal method
time domain reflectrometry
measurement
