Clay loam in Haidian District , Beijing was selected as research object and the impacts of soil volume moisture content (6%-36%), soil urea content (0-1%), soil bulk density (1.2-2.6 g· cm-3 ), temperature (10-50 ℃), salt content (0-0.42%) on soil dielectric properties were explored and analyzed by vector network analyzer NA7300 A based on parallel plate technology within the test frequency ( 40 -150 MHz ) , and estimation model of reactance with soil dielectric properties was built .It was shown that the reactance had good linear relation with soil moisture content at the range of 6%-30%under different test frequencies .The reactance value increased with the increase of moisture content .When the test frequency was 100 MHz, the determination coefficient ( R2 ) of the constructed linearity was higher than 0.97 .Urea did not cause the change of reactance value regularly .With the increase of bulk density , soil salinity and temperature , reactance value increased .The multiple linear regression model was established with reactance as the dependent variable and soil moisture content , bulk density , temperature , salt content and test frequency as independent variables , of which the determination coefficient ( R2 ) was 0.92 , and the probability ( P) was less than the significance level of 0.05 .The results showed that the model could be used as estimation model to study the dielectric properties of clay loam in Beijing .%以北京市海淀区八家试验苗圃的黏壤土为研究对象,使用矢量网络分析仪NA7300 A和平行板技术,探索40~150 MHz频率范围内,土壤体积含水率(6%~36%)、土壤尿素含量(0~1%)、土壤容重(1.2~2.6 g·cm-3)、温度(10~50℃)和含盐量(0~0.42%)对土壤介电特性的影响,并构建表征土壤介电特性的电抗估算模型.结果表明:土壤体积含水率在6%~30%范围内,不同测试频率下,电抗与含水率均具有良好的线性关系,电抗随含水率的增加而增大,当测试频率为100 MHz时,二者的线性度尤其好,决定系数(R2)大于0.97;尿素不会引起电抗值有规律的改变;随着土壤容重、含盐量增大以及温度升高,电抗增大.以电抗为因变量,含水率、容重、温度、含盐量、测试频率为自变量建立的多元线性回归模型的判定系数(R2)为0.92,概率P值小于显著性水平0.05,说明该模型可作为土壤介电特性估算模型,用于北京地区粘壤土的介电特性研究.
展开▼
