基于土壤多参数监测系统的田间持水量试验研究

Experimental study on field capacity based on soil multi-parameter monitoring system

目前田间持水量的测定大多使用传统的人工测量方式,存在耗时长、不能实时测量等问题,为此提出一种基于土壤多参数监测系统测定田间持水量的方法。该方法以饱和土壤含水量自然蒸发为试验基础,分析不同深度的土壤水分曲线在不同阶段的变化情况,探究土壤表层相对温度差对土壤水分日丢失量的影响。结果表明:10 cm深度的土壤水分曲线Y 1在不同观测阶段递减,第15天曲线斜率变小的趋势最明显,20 cm深度的土壤水分曲线Y 2在不同观测阶段递减,在第12天曲线斜率变小的趋势较明显。由土壤体积含水量与观测天数的拟合函数检验指标知,回归模型的决定系数R 2均在0.99以上,表明不同深度的土壤体积含水量与观测天数存在一元二次函数关系。不同深度的土壤水分日丢失量在时间序列上呈现一元三次函数关系变化,而土壤表层相对温度差近似为一个常数,表明土壤水分日丢失量受土壤表层相对温度差的影响较小。使用二次回归模型计算的田间持水量误差为[0.05,0.39],具有更高精度。该方法为土壤监测设备在测定田间持水量中的应用研究提供参考。

At present,the determination of field capacity mostly uses traditional manual measurement methods,which have problems such as time-consuming and inability to measure in real time.Therefore,a method based on soil multi-parameter monitoring system to measure field capacity was proposed.The method was based on the experiment based on the natural evaporation of saturated soil moisture content,analyzed the changes of the soil moisture curve at different depths at different stages,and explored the influence of the relative temperature difference of the soil surface on the daily loss of soil moisture.The results showed that the soil moisture curve Y 1 at a depth of 10 cm decreased at different observation stages,and the slope of the curve decreased the most obvious on the 15th day.The soil moisture curve Y 2 at a depth of 20 cm decreased at different observation stages,and the slope of the curve decreased more obvious on the 12th day.From the test index of the fitting function of soil volumetric water content and the number of observation days,the determination coefficient R 2 of the regression model was all above 0.99,indicating that there was a quadratic function relationship between the soil volumetric water content of different depths and the number of observation days.The daily loss of soil moisture at different depths showed a one-dimensional cubic function relationship in the time series,and the relative temperature difference of the soil surface was approximately a constant,indicating that the daily loss of soil moisture was less affected by the relative temperature difference of the soil surface.The error of field capacity calculated using the quadratic regression model was[0.05,0.39],which had higher accuracy.The method provides reference for the application research on soil monitoring equipment in the determination of field capacity.