Construction and calibration of TDR probes for volumetric water content estimation in a Distroferric Red Latosol

Engenharia Agrícola

Rosimaldo Soncela²  Silvio C. Sampaio¹  Marcio A. Vilas Boas¹  Maria H. F. Tavares¹  Adriana Smanhotto¹ 

[1] ,Instituto Federal de Mato Grosso do SulNova Andradina MS ,Brasil

关键词: apparent dielectric constant;    time-domain reflectometry;    soil water content;    Constante dielétrica aparente;    Reflectometria no domínio do tempo;    Umidade do solo;   

DOI  :  10.1590/S0100-69162013000500004

来源: SciELO

【 摘 要 】

The determination of volumetric water content of soils is an important factor in irrigation management. Among the indirect methods for estimating, the time-domain reflectometry (TDR) technique has received a significant attention. Like any other technique, it has advantages and disadvantages, but its greatest disadvantage is the need of calibration and high cost of acquisition. The main goal of this study was to establish a calibration model for the TDR equipment, Trase System Model 6050X1, to estimate the volumetric water content in a Distroferric Red Latosol. The calibration was carried out in a laboratory with disturbed soil samples under study, packed in PVC columns of a volume of 0.0078m³. The TDR probes were handcrafted with three rods and 0.20m long. They were vertically installed in soil columns, with a total of five probes per column and sixteen columns. The weightings were carried out in a digital scale, while daily readings of dielectric constant were obtained in TDR equipment. The linear model θν = 0.0103 Ka + 0.1900 to estimate the studied volumetric water content showed an excellent coefficient of determination (0.93), enabling the use of probes in indirect estimation of soil moisture.

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