Effect of sensor installation on the accurate measurement of soil water content
Effect of sensor installation on the accurate measurement of soil water content
复制标题
传感器安装对土壤含水量精确测量的影响
DOI：
10.1111/ejss.12493
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发表时间：
2017
影响因子：
4.2
通讯作者：
Nishiya M.
中科院分区：
文献类型：
--
作者：
Iwata Y.;Miyamoto T.;Kameyama K.;Nishiya M.
我们用6种土壤类型和3种传感器安装方法评估了电容式土壤湿度传感器不同安装方法对传感器输出的影响。方法1：先将传感器放入容器中，然后埋置。对于方法2，将整个传感器（包括尖头和电路）插入预包装的土壤样品中。对于方法3，将传感器尖头直接安装到预包装的土壤样品中，然后将土壤放置在电路周围。对于大多数土壤类型的体积土壤含水量（θ），方法1的传感器输出值明显小于其他两种方法的传感器输出值。与安装方法相关的传感器输出差异很大，这导致使用土壤湿度传感器时的估计误差很大。例如，方法1和方法2得到的校准方程计算出的θ值差值为0.076 m3m−3，这是Andisol样品的最大值。我们观察到θ的最大差异（可能是不同传感器安装方法的结果）与土壤水特征曲线确定的粗孔体积之间存在显著的线性关系。传感器安装引起的传感器周围的压实，对于有许多粗孔的土壤可能是相当大的，被认为是土壤湿度传感器输出值增加的主要原因。对于方法2或方法3安装的传感器，除了粘土含量为bb0 ~ 40%或容重非常低的土壤外，可以使用二阶多项式方程将传感器输出精确地转换为θ。一个合适的校准方程对于精确监测土壤含水量至关重要。不同的传感器安装方法对标定方程的影响尚未确定。安装方法对电容传感器的输出值有很大影响。传感器安装的土壤压实增加了传感器输出，在粗孔土壤中更是如此。
We evaluated the effects of different methods of installing a capacitance soil moisture sensor on the sensor's output with six soil types and three methods of sensor installation. For Method 1, the sensor was first placed in a container and then buried. For Method 2, the entire sensor (including prongs and circuitry) was inserted into a prepacked soil sample. For Method 3, the sensor prongs were installed directly into a prepacked soil sample, and then soil was placed around the circuitry. The sensor outputs of Method 1 were significantly smaller for the volumetric soil water content (θ) of most of the soil types compared with the sensor outputs of the other two methods. Large differences in sensor outputs were observed in relation to the installation method, which resulted in a large estimation error when using a soil moisture sensor. For example, the difference inθvalues calculated by the calibration equation obtained by Methods 1 and 2 was 0.076 m3m−3, a maximum for the Andisol sample. We observed a significant linear relation between the maximum differences inθ(which might result from the different sensor installation methods) and the coarse pore volume determined from soil water characteristic curves. Compaction around the sensor induced by sensor installation, which might be considerable for soil with many coarse pores, was considered the main reason for an increase in the soil moisture sensor's output value. For the sensor installed by Methods 2 or 3, a second‐order polynomial equation could be used to translate sensor output toθaccurately except for soils with > 40% clay content or very low bulk density.HighlightsAn appropriate calibration equation is important to monitor soil water content precisely.Effects of different sensor installation methods on calibration equations have not been determined.Method of installation considerably affected output values of a capacitance sensor.Soil compaction by sensor installation increases the sensor output: more so in coarse pore soil.