Calibration of a capacitance system for measuring water content of tropical soil
Calibration of a capacitance system for measuring water content of tropical soil
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DOI：
10.2136/vzj2005.0028
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发表时间：
2005-11-01
影响因子：
2.8
通讯作者：
Ryder, MH
中科院分区：
文献类型：
--
作者：
Polyakov, V;Fares, A;Ryder, MH
电容传感器在过去的几十年里有了很大的改进，因此得到了广泛的接受。新一代多传感器电容系统(MCS)现已面市，易于安装和使用。在野外和实验室条件下，对风化粘壤土和硅砂进行了电容式传感器的标定。这项研究的具体目标是(I)在硅砂和土壤中进行新的MCS的野外和实验室校准，(Ii)评估MCS在收缩膨胀热带土壤中的性能，以及(Iii)评估介质温度对恒定含水率下MCS读数的影响。建立了三参数功率型校正方程。实验室柱标法对土壤和沙子的相关系数分别为0.96和0.97，高于草地(R2=0.73)和耕作土壤(R2=0.74)。制造商的默认模型在较高的水分范围(0.35-0.45 cm(3)cm(-3))内与田间数据吻合得很好。然而，它在干燥范围(0.2-0.35 cm(3)cm(-3))表现不佳，严重低估了土壤水分。土壤的收缩和膨胀以及结合水的存在可能影响了传感器的性能。在45摄氏度的区间内，土壤的实际含水率被高估了15%，沙子只高估了10%。沙土和土壤的相关系数R-2均为0.001.99，具有极显著的统计学意义(P<；MCS的使用适用于热带土壤；然而，需要对特定地点进行校准，以改进对土壤水分的估计。
Capacitance sensors have improved substantially in the last decades, resulting in their wide acceptance. A new generation of multisensor capacitance systems (MCS) is now available that are easy to install and use. Calibration of capacitance sensors was conducted for a weathered clay loam soil and silica sand in field and laboratory conditions. The specific objectives of this research were to (i) conduct field and laboratory calibration of a new MCS in silica sand and soil, (ii) evaluate the performance of MCS for a shrinking-swelling tropical soil, and (iii) evaluate the effect of medium temperature on the MCS reading at constant water content. Three-parameter power type calibration equations were developed. The laboratory column calibration had higher correlation coefficients (R-2 = 0.96 and 0.97 for soil and sand, respectively) than the rangeland (R-2 = 0.73) and cultivated soils (R-2 = 0.74). The manufacturer default model fitted the field data reasonably well in the higher moisture range (0.35-0.45 cm(3) cm(-3)). However, it performed poorly in the dryer range (0.2-0.35 cm(3) cm(-3)), severely underestimating soil moisture content. Shrinking and swelling of soil and the presence of bound water might have affected the sensor's performance. Across the 45 degrees C interval, there was 15% overestimation of the actual water content for soil and only 10% for sand. The relationship was statistically highly significant (P < 0.001) with an R-2 = 0.99 for both sand and soil. Use of MCS is suitable for tropical soil; however, site specific calibration is needed to improve the estimates of soil water content.