African Journal of
Agricultural Research

  • Abbreviation: Afr. J. Agric. Res.
  • Language: English
  • ISSN: 1991-637X
  • DOI: 10.5897/AJAR
  • Start Year: 2006
  • Published Articles: 6574

Full Length Research Paper

Construction and assessment of a hydraulic weighing lysimeter

Jeremias Caetano da Silva,
  • Jeremias Caetano da Silva,
  • Institute of Agricultural Sciences and Technology, Department of Agricultural and Environmental Engineering, Federal University of Mato Grosso, Brazil
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Tonny José Araújo da Silva
  • Tonny José Araújo da Silva
  • Institute of Agricultural Sciences and Technology, Department of Agricultural and Environmental Engineering, Federal University of Mato Grosso, Brazil
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Edna Maria Bonfim-Silva
  • Edna Maria Bonfim-Silva
  • Institute of Agricultural Sciences and Technology, Department of Agricultural and Environmental Engineering, Federal University of Mato Grosso, Brazil
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Thiago Franco Duarte
  • Thiago Franco Duarte
  • Institute of Agricultural Sciences and Technology, Department of Agricultural and Environmental Engineering, Federal University of Mato Grosso, Brazil
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Adriano Bicioni Pacheco
  • Adriano Bicioni Pacheco
  • Institute of Agricultural Sciences and Technology, Department of Agricultural and Environmental Engineering, Federal University of Mato Grosso, Brazil
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  •  Received: 11 December 2015
  •  Accepted: 17 February 2016
  •  Published: 17 March 2016

Abstract

Hydraulic weighing lysimeters have been showing good results in evapotranspiration studies. Thus, the aim of this study was to construct, calibrate, and assess a small (0.7 m3) and low cost hydraulic weighing lysimeter. The lysimeter consists of two containers. The inner container has a circular area of 1 m2​​ and volume of 0.7 m3, while the outer container is constructed with concrete slabs. The inner container is supported by three hydraulic load cells, arranged in the shape of an equilateral triangle. For calibration, standard weights with 1 kg were added and subsequently removed. Calibration results indicated high linearity between mass changes and their readings, with determination coefficient of 0.999. For pressure readings automation, it is necessary to correct temperature-related errors. Wind causes mechanical oscillations in the lysimeter, with subsequent pressure data errors that need to be corrected for proper evaporation measurements, especially in smaller time scales. Comparison between measured ETo and ETo estimated by Penman-Monteith method obtained a coefficient of determination of 0.56.

 

Key words: Evapotranspiration, calibration, hydraulic load cell, pressure gauge.