不同原理土壤水分传感器的室内外标定方法及对比测试研究

Research of Calibration Methods and Contrast Tests of Soil Moisture Sensors with Different Working Principles

土壤水分是地表水循环的关键环节,也是农林系统的重要状态指标。土壤水分观测系统的研制有利于土壤水分的有效观测,从而及时掌握其时空动态变化规律。当前存在多种土壤水分传感器,如常见的基于不同工作原理的频域传感器(Frequency domain spec-troscopy,FDS)和电感传感器等,其成本、土壤含水量-信号曲线以及影响因素均有较大差异。选用国产的FDS传感器,研制了信号采集和长期存储的数据采集器,制成了低成本土壤水分观测系统。同时设计了基于不同试验条件与水分含量的室内控制试验和室外现场同步观测试验,将研制系统的观测结果与美国HOBO土壤水分观测系统的观测结果、环刀取样测试结果进行了比对分析。结果表明:土壤水分含量较低时,研制的土壤水分观测系统观测结果与实际值较接近,优于HOBO观测结果,且适用于瞬时速测和定点长期观测。HOBO传感器在不同环境下表现更为稳定,观测结果值域变化范围较小。盐度对2种土壤水分传感器测量结果均有重要影响。

Soil moisture is the key link in the process of surface water cycle and also the important state index of the agroforestry system. The development of soil moisture observation system is helpful to effective soil moisture observation and grasping the time and space dynamic change rule timely. There are a variety of soil moisture sensors currently, such as Frequency domain sensors absed on different working principles （ Frequency domain spectroscopy, FDS） and the inductance sensors. The sensors are largely different in their costs, the soil moisture content- signal curves and the influence factors. A soil moisture observation system was developed containing FDS sensors, which was low cost and a signals acquirer and long-term database. Some interior control experiments and outdoor field synchronous observation experiments were conduc- ted by using FDS sensors and an American-made soil moisture observation system named HOBO. The experimental results of the two observa- tion systems had been compared with the results of cutting ring sample testing under the condition of different experimental conditions and mois- ture content. The experimental results show that our system has a better respond than HOBO＇ s when the soil moisture content is low because of less gaps to the actual values and our system suits both quick measure and long-term fixed-point observation. Results also show that HOBO system is more stable in different environmental states, but its observation range is narrower. And the experiments saw that the salinity has an important influence to the two kinds of sensors.