管针式土壤含水率探头设计与影响因素分析  

Tube-pin Type Soil Moisture Content Probe and Its Influence Factors

作　　者：郭文川[1] 宋克鑫[1] 韩文霆[2,3] 

机构地区：[1]西北农林科技大学机械与电子工程学院,陕西杨凌712100 [2]西北农林科技大学水土保持研究所,陕西杨凌712100 [3]西北农林科技大学中国旱区节水农业研究院,陕西杨凌712100

出　　处：《农业机械学报》2015年第5期115-121,共7页Transactions of the Chinese Society for Agricultural Machinery

基　　金：'十二五'国家科技支撑计划资助项目(2011BAD29B08);高等学校学科创新引智计划'111'资助项目(B12007)

摘　　要：为了给基于频域反射法测量土壤质量含水率提供一种方法,设计了一种由圆管和探针组成的管针式土壤质量含水率测量探头。以杨凌地区的塿土为对象,分析了所设计探头间接测量土壤容重的误差;在信号源频率为50、100、150、300、500 MHz下,研究了土壤质量含水率（2.58%～21.43%）、土壤容重（0.80～1.30 g/cm3）和温度（10～50℃）对探针上的电压与信号源输出电压的比值（信号电压比）的影响;建立了信号电压比与土壤温度、容重和质量含水率之间的三元二次方程,分析了模型预测土壤含水率的可行性。结果表明：管针式探头间接测量土壤容重的绝对误差为-0.129～0.016 g/cm3;含水率、容重和温度均影响信号电压比,50、100、150 MHz下含水率对信号电压比影响较显著。在0.01的显著水平上,150 MHz下所建模型较优,其决定系数R2为0.849 6;对该模型的检验结果说明,计算的信号电压比与实际电压比的绝对误差为-0.166～0.159。基于该模型计算的土壤含水率与实际含水率的绝对误差为-3.440%～4.039%。To provide a method for measuring soil moisture content in mass based on frequency domain reflectometry, a tube-pin type soil mass moisture content probe, consisting of a tube and a pin, was designed. Lou soil was used as sample to test the probe＇ s performance in measuring bulk density. At 50, 100, 150, 300 and 500 MHz of the signal frequency, the influence of mass moisture content from 2.58% to 21.43%, bulk density from 0. 80 g,/cm3 to 1.30 g/cm3 and temperature from 10~C to 50~C on voltage ratio at probe to source signal were studied. Mathematical models describing the voltage ratio as functions of moisture content, temperature and bulk density were established. The feasibility of the models in predicting moisture content from voltage ratio, moisture content and temperature were analyzed. The results indicated that the absolute error of probe in measuring soil＇s bulk density was within -0. 129 0. 016 g./cm3. Soil moisture content, temperature, bulk density and signals＇ frequency had obvious effects on voltage ratio. At 50, 100 and 150 MHz, moisture content had obvious influence on voltage ratio. The model at 150 MHz was better than the others at 0.01 significance level with the coefficient of determination of 0. 849 6. The absolute error between calculated voltage ratio and actual voltage ratio was within -0. 166 -0. 159. The absolute error between calculated soil moisture content and actual moisture content was within -3.440% -4. 039%.

关 键 词：探头 土壤含水率 管针式 设计 

分 类 号：S24[农业科学—农业电气化与自动化]